analogy introduction essay

30 Writing Topics: Analogy

Ideas for a Paragraph, Essay, or Speech Developed With Analogies

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• An Introduction to Punctuation
• Ph.D., Rhetoric and English, University of Georgia
• M.A., Modern English and American Literature, University of Leicester
• B.A., English, State University of New York

An analogy is a kind of comparison that explains the unknown in terms of the known, the unfamiliar in terms of the familiar.

A good analogy can help your readers understand a complicated subject or view a common experience in a new way. Analogies can be used with other methods of development to explain a process , define a concept, narrate an event, or describe a person or place.

Analogy isn't a single form of writing. Rather, it's a tool for thinking about a subject, as these brief examples demonstrate:

• "Do you ever feel that getting up in the morning is like pulling yourself out of quicksand? . . ." (Jean Betschart, In Control , 2001)
• "Sailing a ship through a storm is . . . a good analogy for the conditions inside an organization during turbulent times, since not only will there be the external turbulence to deal with, but internal turbulence as well . . ." (Peter Lorange, Leading in Turbulent Times , 2010)
• "For some people, reading a good book is like a Calgon bubble bath — it takes you away. . . ." (Kris Carr, Crazy Sexy Cancer Survivor , 2008)
• "Ants are so much like human beings as to be an embarrassment. They farm fungi, raise aphids as livestock, launch armies into wars, use chemical sprays to alarm and confuse enemies, capture slaves. . . ." (Lewis Thomas, "On Societies as Organisms," 1971)
• "To me, patching up a heart that'd had an attack was like changing out bald tires. They were worn and tired, just like an attack made the heart, but you couldn't just switch out one heart for another. . . ." (C. E. Murphy, Coyote Dreams , 2007)
• "Falling in love is like waking up with a cold — or more fittingly, like waking up with a fever. . . ." (William B. Irvine, On Desire , 2006)

British author Dorothy Sayers observed that analogous thinking is a key aspect of the writing process . A composition professor explains:

Analogy illustrates easily and to almost everyone how an "event" can become an "experience" through the adoption of what Miss [Dorothy] Sayers called an "as if" attitude. That is, by arbitrarily looking at an event in several different ways, "as if" if it were this sort of thing, a student can actually experience transformation from the inside. . . . The analogy functions both as a focus and a catalyst for "conversion" of event into experience. It also provides, in some instances not merely the To discover original analogies that can be explored in a paragraph , essay, or speech, apply the "as if" attitude to any one of the 30 topics listed below. In each case, ask yourself, "What is it like ?"

Thirty Topic Suggestions: Analogy

• Working at a fast-food restaurant
• Moving to a new neighborhood
• Starting a new job
• Quitting a job
• Watching an exciting movie
• Reading a good book
• Going into debt
• Getting out of debt
• Losing a close friend
• Leaving home for the first time
• Taking a difficult exam
• Making a speech
• Learning a new skill
• Gaining a new friend
• Responding to bad news
• Responding to good news
• Attending a new place of worship
• Dealing with success
• Dealing with failure
• Being in a car accident
• Falling in love
• Getting married
• Falling out of love
• Experiencing grief
• Experiencing joy
• Overcoming an addiction to drugs
• Watching a friend destroy himself (or herself)
• Getting up in the morning
• Resisting peer pressure
• Discovering a major in college
• The Value of Analogies in Writing and Speech
• Understanding Analogy
• 30 Writing Topics: Persuasion
• Learn How to Use Extended Definitions in Essays and Speeches
• Development in Composition: Building an Essay
• 501 Topic Suggestions for Writing Essays and Speeches
• Topic In Composition and Speech
• Definition and Examples of Transitional Paragraphs
• List of Topics for How-to Essays
• How to Structure an Essay
• How to Write a Narrative Essay or Speech
• The Ultimate Guide to the 5-Paragraph Essay
• Conclusion in Compositions
• How to Write a Great Essay for the TOEFL or TOEIC
• Understanding Organization in Composition and Speech
• Personal Essay Topics

What is an Analogy? Explained With 10 Top Examples

What is an analogy? Read our guide with top examples and in-depth explanations so you can wrap your head around this literary device.

Literary devices make your prose more colorful and vivid, allowing the reader to make associations. What is an analogy? An analogy compares two seemingly unlike things to help draw a conclusion by highlighting their similarities. Unlike other comparisons, like similes and metaphors, an analogy gives more detail about the comparison to help the reader understand it better. 

While there are many different types of analogy to study, the best way to understand this and other figures of speech is to consider examples. After reading a few analogies, you will be better equipped to spot them or write your own. And when you have finished here, check out our comparison article, simile vs metaphor .

What is An Analogy?

What are the benefits of using an analogy, analogy examples, 1. a name is a rose from romeo and juliet, 2. life is a shadow from macbeth, 3. the crowd is like a fisherman in “a hanging”, 4. life is like a box of chocolates from forrest gump, 5. pulling out troops is like salted peanuts from henry kissinger, 6. the futility of a new author from cocktail time, 7. the mystery of life in let me count the ways, 8. the push for freedom is like summer’s heat in “i have a dream”, 9. a needle in a haystack, 10. rearranging deck chairs on the titanic, 11. the matrix’s pill analogy, 12. harry potter and the sorcerer’s stone, what is the opposite of an analogy, what is an example of an analogy, what is the simple definition of analogy, what are 5 examples of analogy, what is another word for an analogy.

An analogy compares two concepts, usually to explain or clarify an idea. Writers use analogies to help people understand complex or abstract topics by relating something abstract to the familiar or concrete. They also use them as a type of literary device to improve the readability of their works.

By highlighting similarities, a writer helps readers see how one thing works or behaves by comparing the characteristics of abstract ideas to more familiar ideas. As a result, a concept or idea becomes easier to understand and even more memorable.

For example, a news reporter could employ this word analogy: “The presidential race for 2024 is like a chessboard…” Teachers use different types of analogies to demonstrate a concept to a student. For this reason, analogy tests often form part of standardized tests in any good English curriculum.

Analogies work in the real world too! For example, if a running coach wants to explain how a runner can run faster, they could use an analogy like “Pump your arms like a train” to help people understand how they should use their arms and legs to run faster. You might also be interested in learning  what is tautology .

Examples of analogies exist in classic literature, the latest books, movies and TV shows. Here are a few:

Often, analogies compare abstract concepts to something you can touch and feel. There are several examples of analogy in William Shakespeare’s Romeo and Juliet. In this analogy, the playwright compares someone’s name to a rose. The rose retains its sweet smell no matter how it is named, as does the person, regardless of his name. Read our guide to the best books of classic literature .

“If you want my final opinion on the mystery of life and all that, I can give it to you in a nutshell. The universe is like a safe to which there is a combination. But the combination is locked up in the safe.”

Life is a difficult concept to understand, making it a favorite topic for people who write analogies. In Act V of Macbeth, Shakespeare creates an analogy example by comparing a person’s life, and its brevity, to a fleeting shadow:

“Life’s but a walking shadow, a poor player That struts and frets his hour upon the stage And then is heard no more. It is a tale  Told by an idiot, full of sound and fury, Signifying nothing.”

Because life is so fleeting, this analogy works. The reader can see the shadow flitting about on the stage, then disappearing, reminding the reader how short life really is. You might also find these  headings and subheadings examples  helpful.

Some analogies take a little more time to explain yet still compare unlike things to make a point. For example, in his essay entitled  A Hanging  George Orwell describes the crowd gripping a man as they lead him to the gallows. The analogy is the comparison to the way a man would hold a slippery fish:

“They crowded very close about him, with their hands always on him in a careful, caressing grip, as though all the while feeling him to make sure he was there. It was like men handling a fish which is still alive and may jump back into the water. But he stood quite unresisting, yielding his arms limply to the ropes, as though he hardly noticed what was happening.”

This analogy is also an example of a simile because it uses the word “like” to make the comparison. However, because it extends beyond just one statement but has a complete description and explanation, it brings more imagery to the reader’s mind and thus is an analogy. Read our guide to the  best satirical authors .

Some analogies are short and sweet, rather than taking up an entire literary work. In the movie Forrest Gump, both the title character and his mother refer to life as a “box of chocolates.” In one of the most famous figures of speech from this movie, Forest says:

“My mom always said life was like a box of chocolates. You never know what you’re gonna get.”

Though this is a simple statement, it is an example of an analogy. The reader has probably experienced the feeling of grabbing chocolate and wondering what flavor it is, so this is a good analogy. But, like life, that box of chocolates always has the potential to give you the unexpected. You might also be wondering,  what is point of view?

Though technically a historian and not a literary genius, Henry Kissinger was famous for many of his analogies. One of his most commonly quoted is this:

“Withdrawal of U.S. troops will become like salted peanuts to the American public; the more U.S. troops come home, the more will be demanded. This could eventually result, in effect, in demands for unilateral withdrawal.”

This quote comes from a  memorandum Kissinger sent to President Nixon  regarding the conflict in Vietnam. He warned the president that bringing troops home a little at a time would create demand for more withdrawal, just like eating tasty peanuts makes you want to eat more. 

Writing a book is definitely challenging, especially when doing so for the first time. This fact is the source of one famous analogy in literature. In  Cocktail Time , P.G. Wodehouse compares a new author to someone performing an impossible task:

“It has been well said that an author who expects results from a first novel is in a position similar to that of a man who drops a rose petal down the Grand Canyon of Arizona and listens for the echo.”

Clearly, expecting to hear an echo from a rose petal at the Grand Canyon is foolishness. Thus, based on this analogy, the logical argument that expecting to see significant returns from a first novel is also foolish. You might also be wondering  what is a split infinitive .

In his novel  Let Me Count the Ways , Dutch author and journalist  Peter De Vries  compares life and a safe. He writes:

In this analogy, the safe can’t be unlocked. Similarly, the mystery of life is something people can’t fully understand.

Speechwriters who are good at their jobs often use analogies to make their words more memorable. In his famous speech, “I Have a Dream,” Martin Luther King, Jr., makes an analogy between the anger of African-Americans and the heat of summer in this quote:

“This sweltering summer of the Negro’s legitimate discontent will not pass until there is an invigorating autumn of freedom and equality.”

Just like the heat of summer is unquenchable, the frustration of those facing endless prejudice cannot be quenched. Yet when freedom comes, it is like the relief of the cool autumn breeze. This quote is still used today when people remember the famous civil rights activist.

Finding a needle in a haystack is a nearly impossible task. This catchphrase or analogy example is often applied to tasks that seem out of reach. For instance, one common analogy says:

“Finding a good man is as easy as finding a needle in a haystack.”

This analogy indicates it is nearly impossible to find a “good man.” Though unfair to the male gender, it does make its point through the use of analogy. Most people can picture digging through the hay to find a needle, but to no avail, which makes the analogy work.

This analogy does not come from any famous literary work or speech but from a well-known historical moment. The sinking of the Titanic was one such event. Sometimes people, when talking about something futile, will say:

“That’s as useful as rearranging deck chairs on the Titanic.”

Since the Titanic was a doomed vessel, the futility of the effort is seen in this use of figurative language. The phrase can apply to any effort that would not matter because the result is a failure, like the sinking of the infamous ship. Check out our metonymy examples .

In The Matrix , there is a famous scene where Morpheus presents the red pill/blue pill analogy to Neo. The analogy is a turning point in the movie where Neo has to pick which path he wants to go down. The red pill represents embracing the uncomfortable truth and becoming aware of the real world he lives in. The blue pill represents choosing the familiar and comfortable path where he can remain in his world, oblivious to the dark reality he suspects.

“You take the blue pill, the story ends. You wake up in your bed and believe whatever you want to believe. You take the red pill, you stay in Wonderland, and I show you how deep the rabbit hole goes.”

J.K. Rowling uses analogies throughout her works, often to give insight into the minds and personalities of the characters. In Harry Potter and the Sorcerer’s Stone , Professor Dumbledore speaks to Harry and imparts some of his famous wisdom.

“It does not do to dwell on dreams and forget to live.”

In this analogy example sentence, he suggests that while having dreams and aspirations are important, it’s just as important to be grounded and present in the current moment. The analogy aims to show Harry that he should balance his ambition and reality and become mindful in the midst of the chaos that he lives in. It also encourages Harry to let go of regrets and become fully present in his life as it is today.

An antithesis highlights the differences between two contrasting ideas. For example, the analogy “Man plans, and God laughs” shows how we can strive and work towards a goal, only for God or fate to intervene and uproot our best plans. For further reading on a similar subject, check out our post on examples of metaphors in literature .

FAQs About What is an Analogy

An example of an analogy is “Hope is the lighthouse that stands tall amidst the stormy seas of despair.” The analogy emphasizes the idea that hope can help us navigate through the storms of life, guiding us toward a better future and helping us persevere in the face of challenges.

An analogy is a comparison between two things that are alike in some way, often used to help explain something or make it easier to understand.

1. Her laughter was music to his ears. 2. Time is money. 3. He is a shining star in the world of science. 4. The classroom was a zoo during the group activity. 5. Life is a journey with its share of twists and turns.

A related term for analogy is comparison. A comparison is a way of describing the similarities or differences between two things in order to better understand them.

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The word analogy has its origins in Greek analogikótita, meaning proportionality. In ancient times, analogies were used to things by showing how they were related, usually in philosophical arguments. When the Greeks used analogy, they would often compare two sets of words side-by-side to illustrate this relationship. Example: white is to black as on is to off, meaning that black and white are complete opposites.

What is Analogy?

An analogy compares things by showing how they are alike. The comparison is often used to make a point or better describe something. Analogies so more than compare. They show and explain . Analogies are often confused with similes and metaphors. However, they are not the same thing. While similes and metaphors may be used in an analogy, an analogy does more than compare – it explains. It is good to remember:  Similes and Metaphors can be used in Analogy , but not all Analogies are similes or metaphors .

How to pronounce Analogy?

When do writers use analogy.

Writers should use analogy when they want to give readers a better understanding of the abstract or complex. By using an analogy writers make these concepts easier to understand. use Analogy literary device to compare two different things or ideas to explain a concept or make a point. Analogy is often used to simplify an idea or explanation.

A favorite example of analogy is this: “Rearranging those chairs is about as useful as rearranging the chairs on the Titanic. In this instance, the analogy is being used to point out that no matter how many chairs are rearranged doesn’t matter; it’s a futile effort.

Some Tips for Using Analogy in Your Writing

If you wish to work analogy into your writing, there are of course a few tips to follow to achieve the desired effect.

• Think of ways to inspire .
• Think about your audience and use comparisons they will understand.
• Create simple, easy to understand imagery .
• Work to compare and contrast .

And Remember : Analogy not only compares, it shows and explains .

The Two Types of Analogy

There are two types of analogy. These types are:

• Analogies which identify shared relationships – This type of analogy is often found in logical arguments and compares things that are technically unrelated. When using this type of analogy, comparisons are straightforward and generally made in sets. Example: “White is to black like on is to off,” meaning that black and white are total opposites.
• Analogies which identify shared abstractness – Analogies of this type involve two things that are technically unrelated but share similar characteristics and are useful for making your audience understand abstract concepts. For example, “Raising a child is like gardening, it takes both patience and practice.” Since parenting is a complex, abstract concept, this analogy helps to explain that like gardening, you must tend to your children with patience so that they may grow to be strong.

Analogy in Literature 📚

The House in Paris , Elizabeth Bowen uses analogy to say that like the saucer supports the cup, our memories keep love alive.

“Memory is to love what the sauce’r is to cup.”

Another modern example of analogy in literature comes from Peter de Vries in Let Me Count the Ways :

“If you want my final opinion on the mystery of life and all that, I can give it to you in a nutshell. The universe is like a safe to which there is a combination. But the combination is locked up in the safe.”

In this passage, de Vries uses the analogy that like the combination to the safe, life is a mystery, meaning that just as we may never understand the meaning of life, the safe may never be unlocked.

And finally, you cannot have a discussion about literary devices without including Shakespeare . After all, he seems to be a master of them all. In MacBeth , Act V, he compares life to a passing shadow – it is fleeting and comes as easily as it goes.

“Life’s but a walking shadow, a poor player

That struts and frets his hour upon the stage

And then is heard no more. It is a tale

Told by an idiot, full of sound and fury,

Signifying nothing.”

And in Poetry ✍🏽

When examining analogy in poetry, the task can become. Analogies can be harder to identify because in shorter poems, you may find the analogy is not contained to a single line or two but rather, the entire poem. While that’s not the case in our first example, we have included one such example for review.

“T here is no Frigate Like a Book ,” Emily Dickinson – 

“ There is no Frigate like a Book

To take us Lands away

Nor any Coursers like a Page

Of prancing Poetry –

This Traverse may the poorest take

Without oppress of Toll –

How frugal is the Chariot That bears the Human Soul –”

In the poem above, the sections of interest have been highlighted to further explain the analogy in the line (and title), “There is no frigate like a book.” In this line, Dickinson compares a book to a war ship. The abstract concepts Dickinson refers to in this analogy are that of the imagination and the soul. She is saying that a book, like a warship, possesses immense power but also, it has the ability to take the reader all over the world if they can just imagine it.

This example is a little more complex, in that as previously noted,  the entire poem is the analogy. However, what Frost wants to convey is that as the seasons change, life also changes with each passing day. In “ Nothing Gold Can Stay, ” Robert Frost uses analogy to compare seasons to life. He writes:

“Nature’s first green is gold,

Her hardest hue to hold.

Her early leaf’s a flower;

But only so an hour.

Then leaf subsides to leaf.

So Eden sank to grief,

So dawn goes down to day.

Nothing gold can stay.”

As the discussion moves forward, this section ends with William Wadsworth Longfellow and his poem, “ The Day is Done .”

“The day is done, and the darkness

Falls from the wings of Night,

As a feather is wafted downward

From an eagle in his flight.”

In Longfellow’s analogy, he compares the coming of night to a feather falling gently and peacefully from an eagle’s wing.

Analogy in Film and Dialogue 🎥

“Life is like a box of chocolates, you never know what you’re gonna get” – Forrest Gump (1994)

In this clip, Forrest compares life to the unpredictability of a box of chocolates. What the writers of this scene wished to convey is that just as you never know what you’ll get in a box of assorted chocolates, life is equally unpredictable.

Analogy in Advertising 📺

Today, one of the most effective ad campaigns uses people as analogy . This was brought to life in the recent Apple commercial featuring Justin Long as a Mac.

But when it comes to marketing, the analogy itself can become abstract as in the example above. Analogies can be presented as images as in the Amazon shopping logo featuring the shopping cart and the A to Z connected with a smile. More traditional examples include ads such as the ad slogan, “ Like a good neighbor, State Farm is there .” The comparison being made is that of a good neighbor and the insurance company. What means a good neighbor is always there in a time of need and like that neighbor the insurance company will be there ready and waiting when you need it.

Often Mistaken for .. 👥

• Simile – A comparison between two unrelated things using the word “like” or “as.” Example: “The biscuit is as salty as a pickle.”
• Metaphor – A figure of speech describing an action or object in a way that is not literally true. Example: “Bob is a couch potato.”

What is an analogy in literature?

An analogy is a literary device that establishes a relationship based on similarities between two concepts or ideas. By conveying an idea or an argument with the help of an analogous situation, it makes it easier to understand a new idea by comparing it to a familiar one.

How does an analogy differ from a metaphor and a simile?

While analogies, metaphors, and similes all compare two different things, analogies are used for clarification, explanation, or argumentation, showing how two things are alike in more than one aspect. Similes make a comparison using “like” or “as,” and metaphors do so by stating something is something else, often in a more poetic manner.

Why are analogies important in literature?

Analogies are important because they help clarify complex or unfamiliar concepts by comparing them to something more familiar, making the new information easier to grasp. They also enhance the reader’s engagement by encouraging them to make connections between different ideas or themes.

Can you give examples of how analogies are used?

Examples of analogies include comparing the structure of an atom to a solar system to explain electron orbits, or likening the mind to a computer when discussing human memory. These comparisons help clarify the less familiar concept by drawing parallels to something understood.

How can I identify an analogy in a text?

To identify an analogy, look for a comparison that is used to explain, clarify, or argue for a concept through its similarities with another, more familiar concept. Analogies often go beyond simple comparisons to explore the relationships between different aspects of the two subjects being compared.

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Writing An Analogy

TIP Sheet WRITING AN ANALOGY

An analogy is an extended comparison between two things usually thought of as unlike. Analogies illustrate and explain by moving from the familiar to the unfamiliar, comparing several points, each of which has a counterpoint. For example, here is an analogy in which an engineering student explains something relatively unknown (loading a tanker) by using her knowledge of something known (filling pop bottles):

A tank truck usually holds between 4,000 and 6,000 gallons of gasoline. Depending on the tanker, three to six individual compartments hold 600 to 900 gallons of gasoline apiece. The tank that contains the compartments is elliptically shaped to distribute the pressure equally and to allow a more complete flow of air when the gasoline is delivered.

Until recently the only way to load a tanker was to climb up on top, where the openings to the compartments are located. You can easily picture this by visualizing six pop bottles lined up in single file on a table. A man wants to fill up bottle three, so he takes the cap off. He then inserts a small hose into the neck of the bottle and turns on a faucet which is connected to the hose.

A gasoline tanker is loaded in a similar way, but on a much larger scale. A man climbs on top of the tanker and opens a particular compartment by removing the cap. He then takes a hose with a four-foot metal pipe down into the "bottle" (the compartment hole), which measures four inches in diameter. A pump is then turned on, allowing the gasoline to flow into the compartment.

Know your audience In the (admittedly unlikely) event her readers had no prior knowledge of pop bottles, however, this analogy might not be particularly informative. The writer chose this analogy based on the likely knowledge of her audience. When you construct an analogy, be certain that the familiar or known side of the analogy is really familiar and known to your reader. It is useless to explain a mineral's crystal-lattice structure by reference to analytic geometry if your reader knows nothing about analytic geometry.

All of us know many things that we can use to help a reader understand an idea better. Here a geology major shows how the oil seismograph works by comparing it to shouting at a cliff wall:

The oil seismograph is a small portable electronic instrument that detects and measures artificial earthquakes. The purpose of the instrument is to find geological structures that may contain oil. The oil seismograph instrument is not mysterious because it can be compared to shouting at a cliff wall.

Imagine yourself standing near the base of a large cliff. If you shout at the cliff face, you will get an echo because the sound waves bounce back from the "interface" where air meets rock. The sound waves travel at 1,100 feet per second. You can find out how far you are standing from the cliff by measuring the time it takes for your shout to travel from you to the cliff and back again, and then by solving a simple formula for distance.

The function of the oil seismograph is to find out how far down in the earth the horizontal layers of rock are. To discover this distance, the oil seismologist digs a deep hole (usually 100-200 feet). At the bottom of the hole, he explodes a heavy charge of dynamite. Ground waves travel from the explosion down to the layers of rock. At each major interface between the layers, the waves bounce back to the surface. The explosion is similar to shouting at the cliff. Just as sound travels through the air at a certain speed, ground waves travel through the earth, although much faster. Ground waves bounce from rock interfaces as sound waves bounce from a cliff face. And the seismologist can determine distance just as you can determine the distance between you and the cliff.

Know your limits It is said that all analogies limp, that is, they are useful for illustration only as far as they remain reasonable. Therefore, do not try to stretch an analogy too far. Like the fabled camel who first put his nose in the man's tent, then his head and finally his whole body, pushing the man out of the tent, analogies can get out of control unless you know when to stop. Cut out or explain any points that cannot be logically compared.

For example, it might be a fair analogy to say that some professional athletes are treated like kings, that they receive special homage from the public and exemption from some rules, that they are more an expense and a pampered group than an asset to the community. But, except for comic effect, it would be overstatement to compare the equestrian charge of a king at an enemy with a football lineman's charge from the line of scrimmage. Likewise, it would be ridiculous to claim that modern athletes believe themselves divinely ordained to lead their country, or that professional athlete-ship is handed down from father to son by divine right. Just because certain similarities between athletes and kings exist, it doesn't follow that every kingly attribute manifests in modern-day athletes. Do not overconnect the subjects being compared.

Good analogies are vivid and logical, and while they cannot prove an argument, they can offer a picture that is very persuasive.

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11.1 Developing Your Sense of Logic

Learning outcomes.

By the end of this section, you will be able to:

• Identify key rhetorical concepts and thought patterns in a variety of texts.
• Explain how patterns of thought function for different audiences, purposes, and situations.

For the purposes of this course, logic means “reasoning based on thought and evidence.” In practical terms, logic is the ability to analyze and evaluate persuasive or argument writing for effectiveness. By extension, it also means that you can learn to use logic in your own argumentative writing. Like any other new skill, you are likely to learn best when you have a starting point. Here are some suggestions for how to begin thinking and writing logically:

• Approach a topic with an open mind.
• Consider what you already know about the topic.
• Consider what you want to know about the topic.
• Find credible information about the topic.
• Base your judgments of the topic on sound reasoning and evidence.

Once you have formed your opinions on a particular debatable subject, you must decide on the best way to organize them to share with others. Developing your skills in six widely used reasoning strategies , or patterns for thinking and writing, can help you determine the most logical and effective means of organizing information to make your points.

In this chapter, you will examine these six reasoning strategies—analogy, cause and effect, classification and division, comparison and contrast, problem and solution, and definition—that are often used in college classes. In addition, you will consider how writers’ personal views, cultural backgrounds, and purposes for writing help determine

• which reasoning strategy suits their needs; and
• what they decide to include in their writing.

As you progress in your college classes and beyond, you will find these reasoning strategies used in all genres of writing, both nonfiction (e.g., textbooks, how-to books) and fiction (e.g., novels, short stories). Understanding how these strategies work can help you recognize their common formats and analyze what you read; likewise, as a writer, understanding how these strategies work to reflect your thinking can help you determine the strategy you need to use.

Writers frequently use analogy as a strategy to compare two unlike subjects—one subject is familiar to readers, whereas the other is not. To explain or clarify the unfamiliar subject, the writer emphasizes the way or ways in which the two subjects are similar, even though they are dissimilar and unrelated in all other ways. Analogies are basically long forms of similes (short comparisons of unlike elements, based on the word like or as ) or metaphors (short comparisons without signal words). In the example paragraph, the writer explains unfamiliar aspects of the COVID-19 pandemic by comparing it with the more familiar concept of a robbery spree.

Model Paragraph

student sample text Examining COVID-19 is like examining a robbery case in this way: both require a great deal of investigation. Those investigating the causes behind the pandemic look for the history of how the virus spread, and those investigating a crime look for the backstory that might connect the victims and criminals. In addition, the two groups of investigators look at the reasons behind the focus of their study. Medical investigators look at why the virus spread throughout the world; police investigators look at why the crime spree took place in a particular area. Also, both types of investigators are trying to stop whatever or whoever is the focus of their investigation. Medical investigators want to stop the virus; police investigators want to stop the crimes. end student sample text

Cause and Effect

Cause-and-effect writing identifies and examines the reasons (causes) for and consequences (effects) of an action, event, or idea. Cause-and-effect writing often answers the question “Why?” and helps readers understand the connections between what happens because of—or as a result of—something else.

student sample text Ray’s grocery, Artie’s Hardware store, and Cradle and Teen department store all went out of business because a well-known superstore opened in Springdale. Customers who frequented Ray’s, an establishment that had been run by the same family for four generations, used to drive many miles to take advantage of the high quality of items in the meat and deli departments. After the opening of the superstore, however, those same customers found they could get similar items at a savings, even if the quality was not as high as the products at Ray’s. Customers at Artie’s Hardware often talked with owner Artie Shoeman about their hardware needs, but the store did not offer the same variety of items they could find in the superstore. The same was true for those who shopped at Cradle and Teen. The superstore featured lower prices and more variety, even if the items did not match the quality of the items at Cradle and Teen. end student sample text

Classification and Division

Classification and division are actually two closely related strategies, generally discussed together because of their similarity. When using the strategy of division, the writer identifies a single subject or group and explains categories within that subject or group. In other words, the writer divides the larger unit into component parts. When using the strategy of classification, writers do the opposite. They group various elements and place them into larger, more comprehensive categories rather than divide the whole into parts. In general, the reasoning strategy of classification and division looks at smaller elements as parts of a larger element and thus helps readers understand a general concept and the elements that it comprises.

Model Paragraphs

student sample text Extra material in the textbook can be divided into photographs, quotations, and tables. The photographs were all taken by the author and focus on various parts of the life cycle of the plants highlighted in the chapter. In addition, to add color and more information about the subject matter of each chapter, the author has inserted sidebar quotations from both famous and non-famous people. The tables the author has included help readers see more details about the progression of the plants’ spread across the country. end student sample text

student sample text After three months of training, the young dogs were placed into three categories: those who would go directly to permanent homes, those who would repeat the course, and those who would advance to the next level. The dogs that would be homed immediately were those who were far too social or far too active to be service dogs. The dogs that would repeat the course had possibilities as service dogs but needed more discipline and instruction. Their futures were yet to be decided. Those that advanced to the next level were obedient and focused and learned quickly. They displayed great promise as service dogs. end student sample text

Comparison and Contrast

Compare and contrast , one of the most frequently used reasoning strategies, analyzes two (sometimes more) subjects, examining the similarities (comparisons) and differences (contrasts) between them. Nearly everything you can think of can be a subject for comparison and contrast: objects, people, concepts, places, movies, literature, and styles, to name a few. To elaborate on the separate points, writers provide details about each element being compared or contrasted. Comparison and contrast helps readers analyze and evaluate subjects.

This strategy is helpful when the similarities or differences are not obvious and when a significant common thread exists between the subjects. For example, a contrast between an expensive, elegant restaurant and a fast-food restaurant would be useless because the differences are clearly obvious, despite the common thread—both are restaurants. However, not so obvious might be some similarities.

When subjects have no common thread or have obvious shared characteristics, any comparison or contrast makes little sense—like contrasting a fish and a shoe (no common thread) or comparing two fast-food restaurants (obvious similarities). However, a writer actually might find a common thread between a fish and a shoe (perhaps shine or texture or color), and a valid topic of contrast might be differences between the two fast-food restaurants.

student sample text Although they seem different on the surface, one way in which Romantic-period poetry and 1980s rap music are alike is the desire the writers had to create a new approach to their art. They wanted to represent simpler values that were more connected to the natural world, values to which a general audience could relate. For example, in William Wordsworth ’s “Daffodils,” the speaker can escape the depressing, industrialized urban world to find peace in nature by contemplating a field of flowers. Similarly, in the Sugarhill Gang ’s 1979 “Rapper’s Delight,” the band sings of how their beats can lift spirits and cause listeners to dance and forget their woes. However, Romantic-period poetry and 1980s rap music are different in the delivery style and form of the art; “Rapper’s Delight” is set to music, which is an integral part of the piece, but “Daffodils” is not. end student sample text

Problem and Solution

When using this reasoning strategy, writers introduce a predicament or challenging issue (the problem) and offer information about what was done or what should be done to remedy the predicament or issue (the solution). Problem-and-solution writing helps readers understand the complexities of some predicaments and the actions that can improve or eliminate them.

student sample text The issue of combating the spread of hate speech and misinformation on social media can be addressed if more social media providers improve their monitoring services. Aside from creating more algorithms that search for linked key words and phrases, social media providers should increase the number of professional monitors conducting active searches. Additionally, while many platforms such as Twitter and Facebook respond within a few days to reports of posts that violate their policies, more monitors could lessen the amount of time these posts are available. According to Facebook, inappropriate posts are investigated and removed within 24 to 48 hours (Facebook “Community Standards”). Some offenders have been reported multiple times for their platform violations, and social media sponsors should increase their monitoring of those offenders. Although such surveillance would increase the burden on the social media providers, it would help solve the growing challenge of online hate speech and misinformation. end student sample text

When using the reasoning strategy of definition , writers elaborate on the meaning of an idea, a word, or an expression, usually one that is controversial or that can be viewed in multiple ways. Beginning writers tend to think that definition writing looks only at the denotation , or dictionary definition. However, definition writing entails much more than relaying a dictionary definition. It also explains and elaborates on the connotations , the emotions and implications the topic evokes. Definition writing is especially useful for explaining and interpreting terms, ideas, or concepts that are easily or often confused or that have meanings beyond their denotations. Sometimes these meanings are personal interpretations and thus reflect a writer’s particular viewpoint. Additionally, this strategy is beneficial when writers want to explain or reinforce a term before making an argument about a larger concept.

student sample text In everyday speech, the word critical is often used to highlight negative aspects of a topic. If someone says a friend was critical of a new haircut, the implication is that the friend did not like the cut. However, when used in college classes, critical has an expanded meaning: noting both the negative and positive aspects of a topic, examining those aspects in depth, and then making decisions about the discoveries. Students directed to use critical thinking, critical reading, or critical writing should know they are expected to examine all sides of a topic fully, evaluate the validity of those sides, and then make sound judgments on the basis of their evaluation. end student sample text

In this chapter, you have learned about various reasoning strategies that you may use in academic and professional writing. Utilizing these strategies when you write can help you both evaluate and analyze text that you read and create more logical and persuasive arguments.

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• Nov 7, 2022

How to write effective analogies for communicating research

Conducting wet lab research is like creating a recipe for a new dish.

But wait, how are these two things remotely similar?

Well, when you’re preparing reagents, conducting experiments, and interpreting your results… wouldn’t you say that these are analogous to getting ingredients, cooking, and then taste-testing your final product?

And when you think about it, research papers AND recipes are both publishable too!

Though, when your research gets more complicated, finding the right analogy for what you’re doing might be more difficult.

But not impossible!

Read on to learn about how you can write analogies for communicating research! 📝

What is an analogy?

An analogy is a descriptive comparison of similarities between two or more different things. Using comparisons helps to explain complex and new ideas by linking them to something familiar.

Why should researchers use analogies?

In the words of Professor Keith S. Taber , Emeritus Professor of Science Education at the University of Cambridge:

In other words, for researchers working with the world’s most unfamiliar and complex topics, they can use analogies to:

make a complex idea easier to understand for a non-technical audience by likening it to something familiar

paint a picture about what you work on, how it works, and why you work on it

become effective and adaptable science communicators

So all that good stuff aside, how can you come up with a meaningful and creative analogy? 🤔

Step 1 of 3: Gauge who your audience is

The first thing we need to consider is your target audience. Because this will influence what choice of words and references would be most appropriate for your analogy.

Remember, we need to connect the unfamiliar to something that is familiar for your audience.

For instance:

Cultural references — an analogy referencing American football wouldn’t work very well with an international audience, but one about a more common sport like soccer or tennis might!

Historical references — an analogy referencing the Chernobyl disaster in 1986 may not be familiar with more recent generations, but referencing the disaster of COVID-19 might!

Step 2 of 3: Compare different things using metaphors and similes

Now that you’ve identified your target audience, it’s time to get creative.

I find myself often bringing back relics of growing up at school; taking classes in areas I would’ve never thought I’d ever revisit! But then I remembered how fun it was to learn about metaphors and similes — two very important linguistic tools for science communicators.

These words might be familiar to you from English class if you ever studied poetry, but if the memories are a bit hazy then here’s a quick recap!

Saying something IS something else, even if not literally.

i.e. Blood vessels ARE highways in your body.

(By the way, there are some fantastic SciComm podcasts on creating metaphors which we HIGHLY recommend checking out!)

Saying something IS LIKE something else.

i.e. Red blood cells ARE LIKE cars.

But how do you come up with a good metaphor or simile for your research topic? Well, start by asking yourself these two questions:

What kind of everyday objects look like my topic? 👀 i.e. “Eyes, across different species, are a lot like camera lenses ”

What kind of everyday phenomena work in a similar way to my topic? ⚙️ i.e. “Magnetic attraction works a lot like love, where usually opposite personalities tend to attract ”

Any of these items below for example could be made into a metaphor for blood vessels.

Let’s build on the idea of a highway. You would list what components make up a highway, and if these individual components themselves could be compared to each other. So on and so forth.

You could, for example, make these parallels:

Veins and capillaries are like roads — because blood cells travel through them.

Blood clots are like traffic jams — because they block the highway, and cause problems.

Immune cells are like ambulances and police cars — because they help out our cells, and chase out intruders respectively.

Would you agree that this analogy so far paints a rather vivid picture ?

Food for thought: I would bet that you’re used to saying “Windows” and “Folders” when you’re operating a computer.

But did you know that “Windows” and “Folders” are actually just metaphors for what they were actually called by computer scientists before the 1970’s?

Windows are a metaphor for “Graphical control elements”. These refer to how you view things on a computer, like on a browser or program. Through a window! Who would’ve thought!

Folders on the other hand are a metaphor for “File directories”. Because folders contain, and direct you to... well… files! Duh!

This was coined the Desktop Metaphor , which helped reduce the barrier to entry for using computers by comparing its functions to things you’d find on a desk, or in the home.

Step 3 of 3: Fine-tune the technical aspects of your analogy

Once you’ve thought up the broad similarities between the things you’re comparing, you can further expand your analogy to various degrees of scientific accuracy.

For example:

Certain types of immune cells are definitely more like police cars than others. Some, like the dendritic cell, can even capture criminals (pathogens and foreign materials), and then take them back to an interrogation site (the spleen).

Some immune cells (certain types of Helper T-cells) are actually more like fire trucks which communicate (via cytokine signalling) to nearby traffic that there’s danger. Then, they can even help put out a fire at a site of inflammation (via anti-inflammatory cytokines).

But inherently because all analogies are simplifications, you will have to find the right balance between accuracy versus ease of understanding. Though, this can depend on your target audience.

Tip the scales depending on what matters more to your audience!

Simplifications can introduce error. But this isn’t necessarily a bad thing.

John Pollack, who served as the US presidential speech writer for Bill Clinton, who is now a leading authority in wordplay, noted in his TEDx talk that :

So yes, analogies can be wrong. If for example you kept working with the blood vessel analogy, you might run into some “technical” miscommunications like these ones below:

Veins and capillaries are technically only one-way roads, as blood flows unidirectionally.

While some immune cells can be compared to ambulances, technically they don’t carry our cells back to be nursed at a hospital.

But even if you were to make an oversimplification, people are STILL LIKELY to get what you mean! If that weren’t the case, then movies like Osmosis Jones and long-running series like Cells At Work! wouldn’t be understandable at all!

And also, there’s no shame in admitting the weaknesses of your analogy.

So try your ideas out even if they’re a stretch 👍

For visual learners who prefer to plan things out on paper, we recommend creating a Venn Diagram or perhaps a mind map like this:

You can also assess the strengths and weaknesses of your analogy. For this, we would highly recommend sharing your analogy with someone who is familiar with your field, and then with someone who isn’t. They’ll likely give you two very different perspectives that could help you fine-tune your analogy further! Or perhaps you could dedicate part of your lab meeting for a group analogy brainstorming session? Leverage all of that scientist brain power in the room! 🧠

Though we totally understand that coming up with a good analogy can take time. But once you’e got one — I’m sure you’ll use it ALL the time. Consider it as a solid time investment!

Once you’ve got one to work with, it’s time to put it into practice. 👇

Apply an analogy in your research outputs

Have you thought about an analogy that works for your research? Or perhaps you’ve thought of multiple?

Here’s a few instances where your analogy could easily get some mileage:

Scientific poster titles

Your title slide for a presentation

Coming up with a concept for a graphical abstract or video abstract

Find, or better yet create , some images to support your analogy too.

And if you’re up for an even bigger challenge, try to communicate your analogy through:

The introduction of your research paper or literature review

A story during one of your talks, like the 3-Minute thesis!

Coming up with a concept for a scientific journal cover , like the one below!

Though, if you feel like it could work in another scenario, give it a try!

And of course, give it a test run with your friends and family. A good analogy might just be the right way to explain what goes on in the lab while you’re having a dinner table conversation.

So I’m sure by now you can see the power of this amazing, yet simple, linguistic tool!

And what’s the result? 👇

You’ll become thought-provoking.

Your readers will feel familiar and become engaged with your topic.

And you’ll spark that deeply satisfying “Aha!” moment in all of their minds.👇

“Huh, you’re right that a cell IS like a machine because of all of the different parts!”

“Tectonic plates ARE like those moving walkways at airports because they can move in opposite directions!”

”Atoms DO look like tiny solar systems because of how orbitals work!”

There’s just so much that a simple analogy can accomplish! 🙌

Take-away messages

Analogies help your audience to understand your research by making it feel more familiar.

Use a good metaphor or simile as a base for your analogy.

Break down your analogy into smaller analogies to explain it in technical detail.

Find the right balance between scientific accuracy and ease of understanding.

Use them in your research, and even in your daily life, wherever and whenever you can!

Looking to communicate your research story using your own analogy?

Science can really be communicated more clearly and creatively by using analogies.

Here at Animate Your Science, we love translating your research ideas, no matter how complex, into meaningful stories through our explainer video and video abstract services. Because with just the right analogy, just about anyone can understand and appreciate the incredible work that you do.

Now that’s real impact.

You can watch two of our more recent animations below to get a feel for how your analogy could be brought onto the big screen!

SARS-CoV-2 is a notorious pirate of the seven seas! (Whiteboard animation)

The banking world is like a complex hurdle race! (Motion graphics animation)

If you’re interested in creating a similar video for your research, get in touch with us and let’s bring your ideas to life!

Until next time!

Dr Juan Miguel Balbin

Dr Khatora Opperman

Dr Tullio Rossi

Illustration

Alvin Yanga

Related Posts

Top 5 Science Communication Podcasts

What does it mean to be a science communicator?

5 tips for improving your public speaking skills as a researcher

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Analogy and Analogical Reasoning

An analogy is a comparison between two objects, or systems of objects, that highlights respects in which they are thought to be similar. Analogical reasoning is any type of thinking that relies upon an analogy. An analogical argument is an explicit representation of a form of analogical reasoning that cites accepted similarities between two systems to support the conclusion that some further similarity exists. In general (but not always), such arguments belong in the category of ampliative reasoning, since their conclusions do not follow with certainty but are only supported with varying degrees of strength. However, the proper characterization of analogical arguments is subject to debate (see §2.2 ).

Analogical reasoning is fundamental to human thought and, arguably, to some nonhuman animals as well. Historically, analogical reasoning has played an important, but sometimes mysterious, role in a wide range of problem-solving contexts. The explicit use of analogical arguments, since antiquity, has been a distinctive feature of scientific, philosophical and legal reasoning. This article focuses primarily on the nature, evaluation and justification of analogical arguments. Related topics include metaphor , models in science , and precedent and analogy in legal reasoning .

1. Introduction: the many roles of analogy

2.1 examples, 2.2 characterization, 2.3 plausibility, 2.4 analogical inference rules, 3.1 commonsense guidelines, 3.2 aristotle’s theory, 3.3 material criteria: hesse’s theory, 3.4 formal criteria: the structure-mapping theory, 3.5 other theories, 3.6 practice-based approaches, 4.1 deductive justification, 4.2 inductive justification, 4.3 a priori justification, 4.4 pragmatic justification, 5.1 analogy and confirmation, 5.2 conceptual change and theory development, online manuscript, related entries.

Analogies are widely recognized as playing an important heuristic role, as aids to discovery. They have been employed, in a wide variety of settings and with considerable success, to generate insight and to formulate possible solutions to problems. According to Joseph Priestley, a pioneer in chemistry and electricity,

analogy is our best guide in all philosophical investigations; and all discoveries, which were not made by mere accident, have been made by the help of it. (1769/1966: 14)

Priestley may be over-stating the case, but there is no doubt that analogies have suggested fruitful lines of inquiry in many fields. Because of their heuristic value, analogies and analogical reasoning have been a particular focus of AI research. Hájek (2018) examines analogy as a heuristic tool in philosophy.

Example 1 . Hydrodynamic analogies exploit mathematical similarities between the equations governing ideal fluid flow and torsional problems. To predict stresses in a planned structure, one can construct a fluid model, i.e., a system of pipes through which water passes (Timoshenko and Goodier 1970). Within the limits of idealization, such analogies allow us to make demonstrative inferences, for example, from a measured quantity in the fluid model to the analogous value in the torsional problem. In practice, there are numerous complications (Sterrett 2006).

At the other extreme, an analogical argument may provide very weak support for its conclusion, establishing no more than minimal plausibility. Consider:

Example 2 . Thomas Reid’s (1785) argument for the existence of life on other planets (Stebbing 1933; Mill 1843/1930; Robinson 1930; Copi 1961). Reid notes a number of similarities between Earth and the other planets in our solar system: all orbit and are illuminated by the sun; several have moons; all revolve on an axis. In consequence, he concludes, it is “not unreasonable to think, that those planets may, like our earth, be the habitation of various orders of living creatures” (1785: 24).

Such modesty is not uncommon. Often the point of an analogical argument is just to persuade people to take an idea seriously. For instance:

Example 3 . Darwin takes himself to be using an analogy between artificial and natural selection to argue for the plausibility of the latter:

Why may I not invent the hypothesis of Natural Selection (which from the analogy of domestic productions, and from what we know of the struggle of existence and of the variability of organic beings, is, in some very slight degree, in itself probable) and try whether this hypothesis of Natural Selection does not explain (as I think it does) a large number of facts…. ( Letter to Henslow , May 1860 in Darwin 1903)

Here it appears, by Darwin’s own admission, that his analogy is employed to show that the hypothesis is probable to some “slight degree” and thus merits further investigation. Some, however, reject this characterization of Darwin’s reasoning (Richards 1997; Gildenhuys 2004).

Sometimes analogical reasoning is the only available form of justification for a hypothesis. The method of ethnographic analogy is used to interpret

the nonobservable behaviour of the ancient inhabitants of an archaeological site (or ancient culture) based on the similarity of their artifacts to those used by living peoples. (Hunter and Whitten 1976: 147)

For example:

Example 4 . Shelley (1999, 2003) describes how ethnographic analogy was used to determine the probable significance of odd markings on the necks of Moche clay pots found in the Peruvian Andes. Contemporary potters in Peru use these marks (called sígnales ) to indicate ownership; the marks enable them to reclaim their work when several potters share a kiln or storage facility. Analogical reasoning may be the only avenue of inference to the past in such cases, though this point is subject to dispute (Gould and Watson 1982; Wylie 1982, 1985). Analogical reasoning may have similar significance for cosmological phenomena that are inaccessible due to limits on observation (Dardashti et al. 2017). See §5.1 for further discussion.

As philosophers and historians such as Kuhn (1996) have repeatedly pointed out, there is not always a clear separation between the two roles that we have identified, discovery and justification. Indeed, the two functions are blended in what we might call the programmatic (or paradigmatic ) role of analogy: over a period of time, an analogy can shape the development of a program of research. For example:

Example 5 . An ‘acoustical analogy’ was employed for many years by certain nineteenth-century physicists investigating spectral lines. Discrete spectra were thought to be

completely analogous to the acoustical situation, with atoms (and/or molecules) serving as oscillators originating or absorbing the vibrations in the manner of resonant tuning forks. (Maier 1981: 51)

Guided by this analogy, physicists looked for groups of spectral lines that exhibited frequency patterns characteristic of a harmonic oscillator. This analogy served not only to underwrite the plausibility of conjectures, but also to guide and limit discovery by pointing scientists in certain directions.

More generally, analogies can play an important programmatic role by guiding conceptual development (see §5.2 ). In some cases, a programmatic analogy culminates in the theoretical unification of two different areas of inquiry.

Example 6 . Descartes’s (1637/1954) correlation between geometry and algebra provided methods for systematically handling geometrical problems that had long been recognized as analogous. A very different relationship between analogy and discovery exists when a programmatic analogy breaks down, as was the ultimate fate of the acoustical analogy. That atomic spectra have an entirely different explanation became clear with the advent of quantum theory. In this case, novel discoveries emerged against background expectations shaped by the guiding analogy. There is a third possibility: an unproductive or misleading programmatic analogy may simply become entrenched and self-perpetuating as it leads us to “construct… data that conform to it” (Stepan 1996: 133). Arguably, the danger of this third possibility provides strong motivation for developing a critical account of analogical reasoning and analogical arguments.

Analogical cognition , which embraces all cognitive processes involved in discovering, constructing and using analogies, is broader than analogical reasoning (Hofstadter 2001; Hofstadter and Sander 2013). Understanding these processes is an important objective of current cognitive science research, and an objective that generates many questions. How do humans identify analogies? Do nonhuman animals use analogies in ways similar to humans? How do analogies and metaphors influence concept formation?

This entry, however, concentrates specifically on analogical arguments. Specifically, it focuses on three central epistemological questions:

• What criteria should we use to evaluate analogical arguments?
• What philosophical justification can be provided for analogical inferences?
• How do analogical arguments fit into a broader inferential context (i.e., how do we combine them with other forms of inference), especially theoretical confirmation?

Following a preliminary discussion of the basic structure of analogical arguments, the entry reviews selected attempts to provide answers to these three questions. To find such answers would constitute an important first step towards understanding the nature of analogical reasoning. To isolate these questions, however, is to make the non-trivial assumption that there can be a theory of analogical arguments —an assumption which, as we shall see, is attacked in different ways by both philosophers and cognitive scientists.

2. Analogical arguments

Analogical arguments vary greatly in subject matter, strength and logical structure. In order to appreciate this variety, it is helpful to increase our stock of examples. First, a geometric example:

Example 7 (Rectangles and boxes). Suppose that you have established that of all rectangles with a fixed perimeter, the square has maximum area. By analogy, you conjecture that of all boxes with a fixed surface area, the cube has maximum volume.

Two examples from the history of science:

Example 8 (Morphine and meperidine). In 1934, the pharmacologist Schaumann was testing synthetic compounds for their anti-spasmodic effect. These drugs had a chemical structure similar to morphine. He observed that one of the compounds— meperidine , also known as Demerol —had a physical effect on mice that was previously observed only with morphine: it induced an S-shaped tail curvature. By analogy, he conjectured that the drug might also share morphine’s narcotic effects. Testing on rats, rabbits, dogs and eventually humans showed that meperidine, like morphine, was an effective pain-killer (Lembeck 1989: 11; Reynolds and Randall 1975: 273).

Example 9 (Priestley on electrostatic force). In 1769, Priestley suggested that the absence of electrical influence inside a hollow charged spherical shell was evidence that charges attract and repel with an inverse square force. He supported his hypothesis by appealing to the analogous situation of zero gravitational force inside a hollow shell of uniform density.

Finally, an example from legal reasoning:

Example 10 (Duty of reasonable care). In a much-cited case ( Donoghue v. Stevenson 1932 AC 562), the United Kingdom House of Lords found the manufacturer of a bottle of ginger beer liable for damages to a consumer who became ill as a result of a dead snail in the bottle. The court argued that the manufacturer had a duty to take “reasonable care” in creating a product that could foreseeably result in harm to the consumer in the absence of such care, and where the consumer had no possibility of intermediate examination. The principle articulated in this famous case was extended, by analogy, to allow recovery for harm against an engineering firm whose negligent repair work caused the collapse of a lift ( Haseldine v. CA Daw & Son Ltd. 1941 2 KB 343). By contrast, the principle was not applicable to a case where a workman was injured by a defective crane, since the workman had opportunity to examine the crane and was even aware of the defects ( Farr v. Butters Brothers & Co. 1932 2 KB 606).

What, if anything, do all of these examples have in common? We begin with a simple, quasi-formal characterization. Similar formulations are found in elementary critical thinking texts (e.g., Copi and Cohen 2005) and in the literature on argumentation theory (e.g., Govier 1999, Guarini 2004, Walton and Hyra 2018). An analogical argument has the following form:

• \(S\) is similar to \(T\) in certain (known) respects.
• \(S\) has some further feature \(Q\).
• Therefore, \(T\) also has the feature \(Q\), or some feature \(Q^*\) similar to \(Q\).

(1) and (2) are premises. (3) is the conclusion of the argument. The argument form is ampliative ; the conclusion is not guaranteed to follow from the premises.

\(S\) and \(T\) are referred to as the source domain and target domain , respectively. A domain is a set of objects, properties, relations and functions, together with a set of accepted statements about those objects, properties, relations and functions. More formally, a domain consists of a set of objects and an interpreted set of statements about them. The statements need not belong to a first-order language, but to keep things simple, any formalizations employed here will be first-order. We use unstarred symbols \((a, P, R, f)\) to refer to items in the source domain and starred symbols \((a^*, P^*, R^*, f^*)\) to refer to corresponding items in the target domain. In Example 9 , the source domain items pertain to gravitation; the target items pertain to electrostatic attraction.

Formally, an analogy between \(S\) and \(T\) is a one-to-one mapping between objects, properties, relations and functions in \(S\) and those in \(T\). Not all of the items in \(S\) and \(T\) need to be placed in correspondence. Commonly, the analogy only identifies correspondences between a select set of items. In practice, we specify an analogy simply by indicating the most significant similarities (and sometimes differences).

We can improve on this preliminary characterization of the argument from analogy by introducing the tabular representation found in Hesse (1966). We place corresponding objects, properties, relations and propositions side-by-side in a table of two columns, one for each domain. For instance, Reid’s argument ( Example 2 ) can be represented as follows (using \(\Rightarrow\) for the analogical inference):

Hesse introduced useful terminology based on this tabular representation. The horizontal relations in an analogy are the relations of similarity (and difference) in the mapping between domains, while the vertical relations are those between the objects, relations and properties within each domain. The correspondence (similarity) between earth’s having a moon and Mars’ having moons is a horizontal relation; the causal relation between having a moon and supporting life is a vertical relation within the source domain (with the possibility of a distinct such relation existing in the target as well).

In an earlier discussion of analogy, Keynes (1921) introduced some terminology that is also helpful.

Positive analogy . Let \(P\) stand for a list of accepted propositions \(P_1 , \ldots ,P_n\) about the source domain \(S\). Suppose that the corresponding propositions \(P^*_1 , \ldots ,P^*_n\), abbreviated as \(P^*\), are all accepted as holding for the target domain \(T\), so that \(P\) and \(P^*\) represent accepted (or known) similarities. Then we refer to \(P\) as the positive analogy .

Negative analogy . Let \(A\) stand for a list of propositions \(A_1 , \ldots ,A_r\) accepted as holding in \(S\), and \(B^*\) for a list \(B_1^*, \ldots ,B_s^*\) of propositions holding in \(T\). Suppose that the analogous propositions \(A^* = A_1^*, \ldots ,A_r^*\) fail to hold in \(T\), and similarly the propositions \(B = B_1 , \ldots ,B_s\) fail to hold in \(S\), so that \(A, {\sim}A^*\) and \({\sim}B, B^*\) represent accepted (or known) differences. Then we refer to \(A\) and \(B\) as the negative analogy .

Neutral analogy . The neutral analogy consists of accepted propositions about \(S\) for which it is not known whether an analogue holds in \(T\).

Finally we have:

Hypothetical analogy . The hypothetical analogy is simply the proposition \(Q\) in the neutral analogy that is the focus of our attention.

These concepts allow us to provide a characterization for an individual analogical argument that is somewhat richer than the original one.

An analogical argument may thus be summarized:

It is plausible that \(Q^*\) holds in the target, because of certain known (or accepted) similarities with the source domain, despite certain known (or accepted) differences.

In order for this characterization to be meaningful, we need to say something about the meaning of ‘plausibly.’ To ensure broad applicability over analogical arguments that vary greatly in strength, we interpret plausibility rather liberally as meaning ‘with some degree of support’. In general, judgments of plausibility are made after a claim has been formulated, but prior to rigorous testing or proof. The next sub-section provides further discussion.

Note that this characterization is incomplete in a number of ways. The manner in which we list similarities and differences, the nature of the correspondences between domains: these things are left unspecified. Nor does this characterization accommodate reasoning with multiple analogies (i.e., multiple source domains), which is ubiquitous in legal reasoning and common elsewhere. To characterize the argument form more fully, however, is not possible without either taking a step towards a substantive theory of analogical reasoning or restricting attention to certain classes of analogical arguments.

Arguments by analogy are extensively discussed within argumentation theory. There is considerable debate about whether they constitute a species of deductive inference (Govier 1999; Waller 2001; Guarini 2004; Kraus 2015). Argumentation theorists also make use of tools such as speech act theory (Bermejo-Luque 2012), argumentation schemes and dialogue types (Macagno et al. 2017; Walton and Hyra 2018) to distinguish different types of analogical argument.

Arguments by analogy are also discussed in the vast literature on scientific models and model-based reasoning, following the lead of Hesse (1966). Bailer-Jones (2002) draws a helpful distinction between analogies and models. While “many models have their roots in an analogy” (2002: 113) and analogy “can act as a catalyst to aid modeling,” Bailer-Jones observes that “the aim of modeling has nothing intrinsically to do with analogy.” In brief, models are tools for prediction and explanation, whereas analogical arguments aim at establishing plausibility. An analogy is evaluated in terms of source-target similarity, while a model is evaluated on how successfully it “provides access to a phenomenon in that it interprets the available empirical data about the phenomenon.” If we broaden our perspective beyond analogical arguments , however, the connection between models and analogies is restored. Nersessian (2009), for instance, stresses the role of analog models in concept-formation and other cognitive processes.

To say that a hypothesis is plausible is to convey that it has epistemic support: we have some reason to believe it, even prior to testing. An assertion of plausibility within the context of an inquiry typically has pragmatic connotations as well: to say that a hypothesis is plausible suggests that we have some reason to investigate it further. For example, a mathematician working on a proof regards a conjecture as plausible if it “has some chances of success” (Polya 1954 (v. 2): 148). On both points, there is ambiguity as to whether an assertion of plausibility is categorical or a matter of degree. These observations point to the existence of two distinct conceptions of plausibility, probabilistic and modal , either of which may reflect the intended conclusion of an analogical argument.

On the probabilistic conception, plausibility is naturally identified with rational credence (rational subjective degree of belief) and is typically represented as a probability. A classic expression may be found in Mill’s analysis of the argument from analogy in A System of Logic :

There can be no doubt that every resemblance [not known to be irrelevant] affords some degree of probability, beyond what would otherwise exist, in favour of the conclusion. (Mill 1843/1930: 333)

In the terminology introduced in §2.2, Mill’s idea is that each element of the positive analogy boosts the probability of the conclusion. Contemporary ‘structure-mapping’ theories ( §3.4 ) employ a restricted version: each structural similarity between two domains contributes to the overall measure of similarity, and hence to the strength of the analogical argument.

On the alternative modal conception, ‘it is plausible that \(p\)’ is not a matter of degree. The meaning, roughly speaking, is that there are sufficient initial grounds for taking \(p\) seriously, i.e., for further investigation (subject to feasibility and interest). Informally: \(p\) passes an initial screening procedure. There is no assertion of degree. Instead, ‘It is plausible that’ may be regarded as an epistemic modal operator that aims to capture a notion, prima facie plausibility, that is somewhat stronger than ordinary epistemic possibility. The intent is to single out \(p\) from an undifferentiated mass of ideas that remain bare epistemic possibilities. To illustrate: in 1769, Priestley’s argument ( Example 9 ), if successful, would establish the prima facie plausibility of an inverse square law for electrostatic attraction. The set of epistemic possibilities—hypotheses about electrostatic attraction compatible with knowledge of the day—was much larger. Individual analogical arguments in mathematics (such as Example 7 ) are almost invariably directed towards prima facie plausibility.

The modal conception figures importantly in some discussions of analogical reasoning. The physicist N. R. Campbell (1957) writes:

But in order that a theory may be valuable it must … display an analogy. The propositions of the hypothesis must be analogous to some known laws…. (1957: 129)

Commenting on the role of analogy in Fourier’s theory of heat conduction, Campbell writes:

Some analogy is essential to it; for it is only this analogy which distinguishes the theory from the multitude of others… which might also be proposed to explain the same laws. (1957: 142)

The interesting notion here is that of a “valuable” theory. We may not agree with Campbell that the existence of analogy is “essential” for a novel theory to be “valuable.” But consider the weaker thesis that an acceptable analogy is sufficient to establish that a theory is “valuable”, or (to qualify still further) that an acceptable analogy provides defeasible grounds for taking the theory seriously. (Possible defeaters might include internal inconsistency, inconsistency with accepted theory, or the existence of a (clearly superior) rival analogical argument.) The point is that Campbell, following the lead of 19 th century philosopher-scientists such as Herschel and Whewell, thinks that analogies can establish this sort of prima facie plausibility. Snyder (2006) provides a detailed discussion of the latter two thinkers and their ideas about the role of analogies in science.

In general, analogical arguments may be directed at establishing either sort of plausibility for their conclusions; they can have a probabilistic use or a modal use. Examples 7 through 9 are best interpreted as supporting modal conclusions. In those arguments, an analogy is used to show that a conjecture is worth taking seriously. To insist on putting the conclusion in probabilistic terms distracts attention from the point of the argument. The conclusion might be modeled (by a Bayesian) as having a certain probability value because it is deemed prima facie plausible, but not vice versa. Example 2 , perhaps, might be regarded as directed primarily towards a probabilistic conclusion.

There should be connections between the two conceptions. Indeed, we might think that the same analogical argument can establish both prima facie plausibility and a degree of probability for a hypothesis. But it is difficult to translate between epistemic modal concepts and probabilities (Cohen 1980; Douven and Williamson 2006; Huber 2009; Spohn 2009, 2012). We cannot simply take the probabilistic notion as the primitive one. It seems wise to keep the two conceptions of plausibility separate.

Schema (4) is a template that represents all analogical arguments, good and bad. It is not an inference rule. Despite the confidence with which particular analogical arguments are advanced, nobody has ever formulated an acceptable rule, or set of rules, for valid analogical inferences. There is not even a plausible candidate. This situation is in marked contrast not only with deductive reasoning, but also with elementary forms of inductive reasoning, such as induction by enumeration.

Of course, it is difficult to show that no successful analogical inference rule will ever be proposed. But consider the following candidate, formulated using the concepts of schema (4) and taking us only a short step beyond that basic characterization.

Rule (5) is modeled on the straight rule for enumerative induction and inspired by Mill’s view of analogical inference, as described in §2.3. We use the generic phrase ‘degree of support’ in place of probability, since other factors besides the analogical argument may influence our probability assignment for \(Q^*\).

It is pretty clear that (5) is a non-starter. The main problem is that the rule justifies too much. The only substantive requirement introduced by (5) is that there be a nonempty positive analogy. Plainly, there are analogical arguments that satisfy this condition but establish no prima facie plausibility and no measure of support for their conclusions.

Here is a simple illustration. Achinstein (1964: 328) observes that there is a formal analogy between swans and line segments if we take the relation ‘has the same color as’ to correspond to ‘is congruent with’. Both relations are reflexive, symmetric, and transitive. Yet it would be absurd to find positive support from this analogy for the idea that we are likely to find congruent lines clustered in groups of two or more, just because swans of the same color are commonly found in groups. The positive analogy is antecedently known to be irrelevant to the hypothetical analogy. In such a case, the analogical inference should be utterly rejected. Yet rule (5) would wrongly assign non-zero degree of support.

To generalize the difficulty: not every similarity increases the probability of the conclusion and not every difference decreases it. Some similarities and differences are known to be (or accepted as being) utterly irrelevant and should have no influence whatsoever on our probability judgments. To be viable, rule (5) would need to be supplemented with considerations of relevance , which depend upon the subject matter, historical context and logical details particular to each analogical argument. To search for a simple rule of analogical inference thus appears futile.

Carnap and his followers (Carnap 1980; Kuipers 1988; Niiniluoto 1988; Maher 2000; Romeijn 2006) have formulated principles of analogy for inductive logic, using Carnapian \(\lambda \gamma\) rules. Generally, this body of work relates to “analogy by similarity”, rather than the type of analogical reasoning discussed here. Romeijn (2006) maintains that there is a relation between Carnap’s concept of analogy and analogical prediction. His approach is a hybrid of Carnap-style inductive rules and a Bayesian model. Such an approach would need to be generalized to handle the kinds of arguments described in §2.1 . It remains unclear that the Carnapian approach can provide a general rule for analogical inference.

Norton (2010, and 2018—see Other Internet Resources) has argued that the project of formalizing inductive reasoning in terms of one or more simple formal schemata is doomed. His criticisms seem especially apt when applied to analogical reasoning. He writes:

If analogical reasoning is required to conform only to a simple formal schema, the restriction is too permissive. Inferences are authorized that clearly should not pass muster… The natural response has been to develop more elaborate formal templates… The familiar difficulty is that these embellished schema never seem to be quite embellished enough; there always seems to be some part of the analysis that must be handled intuitively without guidance from strict formal rules. (2018: 1)

Norton takes the point one step further, in keeping with his “material theory” of inductive inference. He argues that there is no universal logical principle that “powers” analogical inference “by asserting that things that share some properties must share others.” Rather, each analogical inference is warranted by some local constellation of facts about the target system that he terms “the fact of analogy”. These local facts are to be determined and investigated on a case by case basis.

To embrace a purely formal approach to analogy and to abjure formalization entirely are two extremes in a spectrum of strategies. There are intermediate positions. Most recent analyses (both philosophical and computational) have been directed towards elucidating criteria and procedures, rather than formal rules, for reasoning by analogy. So long as these are not intended to provide a universal ‘logic’ of analogy, there is room for such criteria even if one accepts Norton’s basic point. The next section discusses some of these criteria and procedures.

3. Criteria for evaluating analogical arguments

Logicians and philosophers of science have identified ‘textbook-style’ general guidelines for evaluating analogical arguments (Mill 1843/1930; Keynes 1921; Robinson 1930; Stebbing 1933; Copi and Cohen 2005; Moore and Parker 1998; Woods, Irvine, and Walton 2004). Here are some of the most important ones:

These principles can be helpful, but are frequently too vague to provide much insight. How do we count similarities and differences in applying (G1) and (G2)? Why are the structural and causal analogies mentioned in (G5) and (G6) especially important, and which structural and causal features merit attention? More generally, in connection with the all-important (G7): how do we determine which similarities and differences are relevant to the conclusion? Furthermore, what are we to say about similarities and differences that have been omitted from an analogical argument but might still be relevant?

An additional problem is that the criteria can pull in different directions. To illustrate, consider Reid’s argument for life on other planets ( Example 2 ). Stebbing (1933) finds Reid’s argument “suggestive” and “not unplausible” because the conclusion is weak (G4), while Mill (1843/1930) appears to reject the argument on account of our vast ignorance of properties that might be relevant (G3).

There is a further problem that relates to the distinction just made (in §2.3 ) between two kinds of plausibility. Each of the above criteria apart from (G7) is expressed in terms of the strength of the argument, i.e., the degree of support for the conclusion. The criteria thus appear to presuppose the probabilistic interpretation of plausibility. The problem is that a great many analogical arguments aim to establish prima facie plausibility rather than any degree of probability. Most of the guidelines are not directly applicable to such arguments.

Aristotle sets the stage for all later theories of analogical reasoning. In his theoretical reflections on analogy and in his most judicious examples, we find a sober account that lays the foundation both for the commonsense guidelines noted above and for more sophisticated analyses.

Although Aristotle employs the term analogy ( analogia ) and discusses analogical predication , he never talks about analogical reasoning or analogical arguments per se . He does, however, identify two argument forms, the argument from example ( paradeigma ) and the argument from likeness ( homoiotes ), both closely related to what would we now recognize as an analogical argument.

The argument from example ( paradeigma ) is described in the Rhetoric and the Prior Analytics :

Enthymemes based upon example are those which proceed from one or more similar cases, arrive at a general proposition, and then argue deductively to a particular inference. ( Rhetoric 1402b15) Let \(A\) be evil, \(B\) making war against neighbours, \(C\) Athenians against Thebans, \(D\) Thebans against Phocians. If then we wish to prove that to fight with the Thebans is an evil, we must assume that to fight against neighbours is an evil. Conviction of this is obtained from similar cases, e.g., that the war against the Phocians was an evil to the Thebans. Since then to fight against neighbours is an evil, and to fight against the Thebans is to fight against neighbours, it is clear that to fight against the Thebans is an evil. ( Pr. An. 69a1)

Aristotle notes two differences between this argument form and induction (69a15ff.): it “does not draw its proof from all the particular cases” (i.e., it is not a “complete” induction), and it requires an additional (deductively valid) syllogism as the final step. The argument from example thus amounts to single-case induction followed by deductive inference. It has the following structure (using \(\supset\) for the conditional):

In the terminology of §2.2, \(P\) is the positive analogy and \(Q\) is the hypothetical analogy. In Aristotle’s example, \(S\) (the source) is war between Phocians and Thebans, \(T\) (the target) is war between Athenians and Thebans, \(P\) is war between neighbours, and \(Q\) is evil. The first inference (dashed arrow) is inductive; the second and third (solid arrows) are deductively valid.

The paradeigma has an interesting feature: it is amenable to an alternative analysis as a purely deductive argument form. Let us concentrate on Aristotle’s assertion, “we must assume that to fight against neighbours is an evil,” represented as \(\forall x(P(x) \supset Q(x))\). Instead of regarding this intermediate step as something reached by induction from a single case, we might instead regard it as a hidden presupposition. This transforms the paradeigma into a syllogistic argument with a missing or enthymematic premise, and our attention shifts to possible means for establishing that premise (with single-case induction as one such means). Construed in this way, Aristotle’s paradeigma argument foreshadows deductive analyses of analogical reasoning (see §4.1 ).

The argument from likeness ( homoiotes ) seems to be closer than the paradeigma to our contemporary understanding of analogical arguments. This argument form receives considerable attention in Topics I, 17 and 18 and again in VIII, 1. The most important passage is the following.

Try to secure admissions by means of likeness; for such admissions are plausible, and the universal involved is less patent; e.g. that as knowledge and ignorance of contraries is the same, so too perception of contraries is the same; or vice versa, that since the perception is the same, so is the knowledge also. This argument resembles induction, but is not the same thing; for in induction it is the universal whose admission is secured from the particulars, whereas in arguments from likeness, what is secured is not the universal under which all the like cases fall. ( Topics 156b10–17)

This passage occurs in a work that offers advice for framing dialectical arguments when confronting a somewhat skeptical interlocutor. In such situations, it is best not to make one’s argument depend upon securing agreement about any universal proposition. The argument from likeness is thus clearly distinct from the paradeigma , where the universal proposition plays an essential role as an intermediate step in the argument. The argument from likeness, though logically less straightforward than the paradeigma , is exactly the sort of analogical reasoning we want when we are unsure about underlying generalizations.

In Topics I 17, Aristotle states that any shared attribute contributes some degree of likeness. It is natural to ask when the degree of likeness between two things is sufficiently great to warrant inferring a further likeness. In other words, when does the argument from likeness succeed? Aristotle does not answer explicitly, but a clue is provided by the way he justifies particular arguments from likeness. As Lloyd (1966) has observed, Aristotle typically justifies such arguments by articulating a (sometimes vague) causal principle which governs the two phenomena being compared. For example, Aristotle explains the saltiness of the sea, by analogy with the saltiness of sweat, as a kind of residual earthy stuff exuded in natural processes such as heating. The common principle is this:

Everything that grows and is naturally generated always leaves a residue, like that of things burnt, consisting in this sort of earth. ( Mete 358a17)

From this method of justification, we might conjecture that Aristotle believes that the important similarities are those that enter into such general causal principles.

Summarizing, Aristotle’s theory provides us with four important and influential criteria for the evaluation of analogical arguments:

• The strength of an analogy depends upon the number of similarities.
• Similarity reduces to identical properties and relations.
• Good analogies derive from underlying common causes or general laws.
• A good analogical argument need not pre-suppose acquaintance with the underlying universal (generalization).

These four principles form the core of a common-sense model for evaluating analogical arguments (which is not to say that they are correct; indeed, the first three will shortly be called into question). The first, as we have seen, appears regularly in textbook discussions of analogy. The second is largely taken for granted, with important exceptions in computational models of analogy ( §3.4 ). Versions of the third are found in most sophisticated theories. The final point, which distinguishes the argument from likeness and the argument from example, is endorsed in many discussions of analogy (e.g., Quine and Ullian 1970).

A slight generalization of Aristotle’s first principle helps to prepare the way for discussion of later developments. As that principle suggests, Aristotle, in common with just about everyone else who has written about analogical reasoning, organizes his analysis of the argument form around overall similarity. In the terminology of section 2.2, horizontal relationships drive the reasoning: the greater the overall similarity of the two domains, the stronger the analogical argument . Hume makes the same point, though stated negatively, in his Dialogues Concerning Natural Religion :

Wherever you depart, in the least, from the similarity of the cases, you diminish proportionably the evidence; and may at last bring it to a very weak analogy, which is confessedly liable to error and uncertainty. (1779/1947: 144)

Most theories of analogy agree with Aristotle and Hume on this general point. Disagreement relates to the appropriate way of measuring overall similarity. Some theories assign greatest weight to material analogy , which refers to shared, and typically observable, features. Others give prominence to formal analogy , emphasizing high-level structural correspondence. The next two sub-sections discuss representative accounts that illustrate these two approaches.

Hesse (1966) offers a sharpened version of Aristotle’s theory, specifically focused on analogical arguments in the sciences. She formulates three requirements that an analogical argument must satisfy in order to be acceptable:

• Requirement of material analogy . The horizontal relations must include similarities between observable properties.
• Causal condition . The vertical relations must be causal relations “in some acceptable scientific sense” (1966: 87).
• No-essential-difference condition . The essential properties and causal relations of the source domain must not have been shown to be part of the negative analogy.

3.3.1 Requirement of material analogy

For Hesse, an acceptable analogical argument must include “observable similarities” between domains, which she refers to as material analogy . Material analogy is contrasted with formal analogy . Two domains are formally analogous if both are “interpretations of the same formal theory” (1966: 68). Nomic isomorphism (Hempel 1965) is a special case in which the physical laws governing two systems have identical mathematical form. Heat and fluid flow exhibit nomic isomorphism. A second example is the analogy between the flow of electric current in a wire and fluid in a pipe. Ohm’s law

states that voltage difference along a wire equals current times a constant resistance. This has the same mathematical form as Poiseuille’s law (for ideal fluids):

which states that the pressure difference along a pipe equals the volumetric flow rate times a constant. Both of these systems can be represented by a common equation. While formal analogy is linked to common mathematical structure, it should not be limited to nomic isomorphism (Bartha 2010: 209). The idea of formal analogy generalizes to cases where there is a common mathematical structure between models for two systems. Bartha offers an even more liberal definition (2010: 195): “Two features are formally similar if they occupy corresponding positions in formally analogous theories. For example, pitch in the theory of sound corresponds to color in the theory of light.”

By contrast, material analogy consists of what Hesse calls “observable” or “pre-theoretic” similarities. These are horizontal relationships of similarity between properties of objects in the source and the target. Similarities between echoes (sound) and reflection (light), for instance, were recognized long before we had any detailed theories about these phenomena. Hesse (1966, 1988) regards such similarities as metaphorical relationships between the two domains and labels them “pre-theoretic” because they draw on personal and cultural experience. We have both material and formal analogies between sound and light, and it is significant for Hesse that the former are independent of the latter.

There are good reasons not to accept Hesse’s requirement of material analogy, construed in this narrow way. First, it is apparent that formal analogies are the starting point in many important inferences. That is certainly the case in mathematics, a field in which material analogy, in Hesse’s sense, plays no role at all. Analogical arguments based on formal analogy have also been extremely influential in physics (Steiner 1989, 1998).

In Norton’s broad sense, however, ‘material analogy’ simply refers to similarities rooted in factual knowledge of the source and target domains. With reference to this broader meaning, Hesse proposes two additional material criteria.

3.3.2 Causal condition

Hesse requires that the hypothetical analogy, the feature transferred to the target domain, be causally related to the positive analogy. In her words, the essential requirement for a good argument from analogy is “a tendency to co-occurrence”, i.e., a causal relationship. She states the requirement as follows:

The vertical relations in the model [source] are causal relations in some acceptable scientific sense, where there are no compelling a priori reasons for denying that causal relations of the same kind may hold between terms of the explanandum [target]. (1966: 87)

The causal condition rules out analogical arguments where there is no causal knowledge of the source domain. It derives support from the observation that many analogies do appear to involve a transfer of causal knowledge.

The causal condition is on the right track, but is arguably too restrictive. For example, it rules out analogical arguments in mathematics. Even if we limit attention to the empirical sciences, persuasive analogical arguments may be founded upon strong statistical correlation in the absence of any known causal connection. Consider ( Example 11 ) Benjamin Franklin’s prediction, in 1749, that pointed metal rods would attract lightning, by analogy with the way they attracted the “electrical fluid” in the laboratory:

Electrical fluid agrees with lightning in these particulars: 1. Giving light. 2. Colour of the light. 3. Crooked direction. 4. Swift motion. 5. Being conducted by metals. 6. Crack or noise in exploding. 7. Subsisting in water or ice. 8. Rending bodies it passes through. 9. Destroying animals. 10. Melting metals. 11. Firing inflammable substances. 12. Sulphureous smell.—The electrical fluid is attracted by points.—We do not know whether this property is in lightning.—But since they agree in all the particulars wherein we can already compare them, is it not probable they agree likewise in this? Let the experiment be made. ( Benjamin Franklin’s Experiments , 334)

Franklin’s hypothesis was based on a long list of properties common to the target (lightning) and source (electrical fluid in the laboratory). There was no known causal connection between the twelve “particulars” and the thirteenth property, but there was a strong correlation. Analogical arguments may be plausible even where there are no known causal relations.

3.3.3 No-essential-difference condition

Hesse’s final requirement is that the “essential properties and causal relations of the [source] have not been shown to be part of the negative analogy” (1966: 91). Hesse does not provide a definition of “essential,” but suggests that a property or relation is essential if it is “causally closely related to the known positive analogy.” For instance, an analogy with fluid flow was extremely influential in developing the theory of heat conduction. Once it was discovered that heat was not conserved, however, the analogy became unacceptable (according to Hesse) because conservation was so central to the theory of fluid flow.

This requirement, though once again on the right track, seems too restrictive. It can lead to the rejection of a good analogical argument. Consider the analogy between a two-dimensional rectangle and a three-dimensional box ( Example 7 ). Broadening Hesse’s notion, it seems that there are many ‘essential’ differences between rectangles and boxes. This does not mean that we should reject every analogy between rectangles and boxes out of hand. The problem derives from the fact that Hesse’s condition is applied to the analogy relation independently of the use to which that relation is put. What counts as essential should vary with the analogical argument. Absent an inferential context, it is impossible to evaluate the importance or ‘essentiality’ of similarities and differences.

Despite these weaknesses, Hesse’s ‘material’ criteria constitute a significant advance in our understanding of analogical reasoning. The causal condition and the no-essential-difference condition incorporate local factors, as urged by Norton, into the assessment of analogical arguments. These conditions, singly or taken together, imply that an analogical argument can fail to generate any support for its conclusion, even when there is a non-empty positive analogy. Hesse offers no theory about the ‘degree’ of analogical support. That makes her account one of the few that is oriented towards the modal, rather than probabilistic, use of analogical arguments ( §2.3 ).

Many people take the concept of model-theoretic isomorphism to set the standard for thinking about similarity and its role in analogical reasoning. They propose formal criteria for evaluating analogies, based on overall structural or syntactical similarity. Let us refer to theories oriented around such criteria as structuralist .

A number of leading computational models of analogy are structuralist. They are implemented in computer programs that begin with (or sometimes build) representations of the source and target domains, and then construct possible analogy mappings. Analogical inferences emerge as a consequence of identifying the ‘best mapping.’ In terms of criteria for analogical reasoning, there are two main ideas. First, the goodness of an analogical argument is based on the goodness of the associated analogy mapping . Second, the goodness of the analogy mapping is given by a metric that indicates how closely it approximates isomorphism.

The most influential structuralist theory has been Gentner’s structure-mapping theory, implemented in a program called the structure-mapping engine (SME). In its original form (Gentner 1983), the theory assesses analogies on purely structural grounds. Gentner asserts:

Analogies are about relations, rather than simple features. No matter what kind of knowledge (causal models, plans, stories, etc.), it is the structural properties (i.e., the interrelationships between the facts) that determine the content of an analogy. (Falkenhainer, Forbus, and Gentner 1989/90: 3)

In order to clarify this thesis, Gentner introduces a distinction between properties , or monadic predicates, and relations , which have multiple arguments. She further distinguishes among different orders of relations and functions, defined inductively (in terms of the order of the relata or arguments). The best mapping is determined by systematicity : the extent to which it places higher-order relations, and items that are nested in higher-order relations, in correspondence. Gentner’s Systematicity Principle states:

A predicate that belongs to a mappable system of mutually interconnecting relationships is more likely to be imported into the target than is an isolated predicate. (1983: 163)

A systematic analogy (one that places high-order relations and their components in correspondence) is better than a less systematic analogy. Hence, an analogical inference has a degree of plausibility that increases monotonically with the degree of systematicity of the associated analogy mapping. Gentner’s fundamental criterion for evaluating candidate analogies (and analogical inferences) thus depends solely upon the syntax of the given representations and not at all upon their content.

Later versions of the structure-mapping theory incorporate refinements (Forbus, Ferguson, and Gentner 1994; Forbus 2001; Forbus et al. 2007; Forbus et al. 2008; Forbus et al 2017). For example, the earliest version of the theory is vulnerable to worries about hand-coded representations of source and target domains. Gentner and her colleagues have attempted to solve this problem in later work that generates LISP representations from natural language text (see Turney 2008 for a different approach).

The most important challenges for the structure-mapping approach relate to the Systematicity Principle itself. Does the value of an analogy derive entirely, or even chiefly, from systematicity? There appear to be two main difficulties with this view. First: it is not always appropriate to give priority to systematic, high-level relational matches. Material criteria, and notably what Gentner refers to as “superficial feature matches,” can be extremely important in some types of analogical reasoning, such as ethnographic analogies which are based, to a considerable degree, on surface resemblances between artifacts. Second and more significantly: systematicity seems to be at best a fallible marker for good analogies rather than the essence of good analogical reasoning.

Greater systematicity is neither necessary nor sufficient for a more plausible analogical inference. It is obvious that increased systematicity is not sufficient for increased plausibility. An implausible analogy can be represented in a form that exhibits a high degree of structural parallelism. High-order relations can come cheap, as we saw with Achinstein’s “swan” example ( §2.4 ).

More pointedly, increased systematicity is not necessary for greater plausibility. Indeed, in causal analogies, it may even weaken the inference. That is because systematicity takes no account of the type of causal relevance, positive or negative. (McKay 1993) notes that microbes have been found in frozen lakes in Antarctica; by analogy, simple life forms might exist on Mars. Freezing temperatures are preventive or counteracting causes; they are negatively relevant to the existence of life. The climate of Mars was probably more favorable to life 3.5 billion years ago than it is today, because temperatures were warmer. Yet the analogy between Antarctica and present-day Mars is more systematic than the analogy between Antarctica and ancient Mars. According to the Systematicity Principle , the analogy with Antarctica provides stronger support for life on Mars today than it does for life on ancient Mars.

The point of this example is that increased systematicity does not always increase plausibility, and reduced systematicity does not always decrease it (see Lee and Holyoak 2008). The more general point is that systematicity can be misleading, unless we take into account the nature of the relationships between various factors and the hypothetical analogy. Systematicity does not magically produce or explain the plausibility of an analogical argument. When we reason by analogy, we must determine which features of both domains are relevant and how they relate to the analogical conclusion. There is no short-cut via syntax.

Schlimm (2008) offers an entirely different critique of the structure-mapping theory from the perspective of analogical reasoning in mathematics—a domain where one might expect a formal approach such as structure mapping to perform well. Schlimm introduces a simple distinction: a domain is object-rich if the number of objects is greater than the number of relations (and properties), and relation-rich otherwise. Proponents of the structure-mapping theory typically focus on relation-rich examples (such as the analogy between the solar system and the atom). By contrast, analogies in mathematics typically involve domains with an enormous number of objects (like the real numbers), but relatively few relations and functions (addition, multiplication, less-than).

Schlimm provides an example of an analogical reasoning problem in group theory that involves a single relation in each domain. In this case, attaining maximal systematicity is trivial. The difficulty is that, compatible with maximal systematicity, there are different ways in which the objects might be placed in correspondence. The structure-mapping theory appears to yield the wrong inference. We might put the general point as follows: in object-rich domains, systematicity ceases to be a reliable guide to plausible analogical inference.

3.5.1 Connectionist models

During the past thirty-five years, cognitive scientists have conducted extensive research on analogy. Gentner’s SME is just one of many computational theories, implemented in programs that construct and use analogies. Three helpful anthologies that span this period are Helman 1988; Gentner, Holyoak, and Kokinov 2001; and Kokinov, Holyoak, and Gentner 2009.

One predominant objective of this research has been to model the cognitive processes involved in using analogies. Early models tended to be oriented towards “understanding the basic constraints that govern human analogical thinking” (Hummel and Holyoak 1997: 458). Recent connectionist models have been directed towards uncovering the psychological mechanisms that come into play when we use analogies: retrieval of a relevant source domain, analogical mapping across domains, and transfer of information and learning of new categories or schemas.

In some cases, such as the structure-mapping theory (§3.4), this research overlaps directly with the normative questions that are the focus of this entry; indeed, Gentner’s Systematicity Principle may be interpreted normatively. In other cases, we might view the projects as displacing those traditional normative questions with up-to-date, computational forms of naturalized epistemology . Two approaches are singled out here because both raise important challenges to the very idea of finding sharp answers to those questions, and both suggest that connectionist models offer a more fruitful approach to understanding analogical reasoning.

The first is the constraint-satisfaction model (also known as the multiconstraint theory ), developed by Holyoak and Thagard (1989, 1995). Like Gentner, Holyoak and Thagard regard the heart of analogical reasoning as analogy mapping , and they stress the importance of systematicity, which they refer to as a structural constraint. Unlike Gentner, they acknowledge two additional types of constraints. Pragmatic constraints take into account the goals and purposes of the agent, recognizing that “the purpose will guide selection” of relevant similarities. Semantic constraints represent estimates of the degree to which people regard source and target items as being alike, rather like Hesse’s “pre-theoretic” similarities.

The novelty of the multiconstraint theory is that these structural , semantic and pragmatic constraints are implemented not as rigid rules, but rather as ‘pressures’ supporting or inhibiting potential pairwise correspondences. The theory is implemented in a connectionist program called ACME (Analogical Constraint Mapping Engine), which assigns an initial activation value to each possible pairing between elements in the source and target domains (based on semantic and pragmatic constraints), and then runs through cycles that update the activation values based on overall coherence (structural constraints). The best global analogy mapping emerges under the pressure of these constraints. Subsequent connectionist models, such as Hummel and Holyoak’s LISA program (1997, 2003), have made significant advances and hold promise for offering a more complete theory of analogical reasoning.

The second example is Hofstadter and Mitchell’s Copycat program (Hofstadter 1995; Mitchell 1993). The program is “designed to discover insightful analogies, and to do so in a psychologically realistic way” (Hofstadter 1995: 205). Copycat operates in the domain of letter-strings. The program handles the following type of problem:

Suppose the letter-string abc were changed to abd ; how would you change the letter-string ijk in “the same way”?

Most people would answer ijl , since it is natural to think that abc was changed to abd by the “transformation rule”: replace the rightmost letter with its successor. Alternative answers are possible, but do not agree with most people’s sense of what counts as the natural analogy.

Hofstadter and Mitchell believe that analogy-making is in large part about the perception of novel patterns, and that such perception requires concepts with “fluid” boundaries. Genuine analogy-making involves “slippage” of concepts. The Copycat program combines a set of core concepts pertaining to letter-sequences ( successor , leftmost and so forth) with probabilistic “halos” that link distinct concepts dynamically. Orderly structures emerge out of random low-level processes and the program produces plausible solutions. Copycat thus shows that analogy-making can be modeled as a process akin to perception, even if the program employs mechanisms distinct from those in human perception.

The multiconstraint theory and Copycat share the idea that analogical cognition involves cognitive processes that operate below the level of abstract reasoning. Both computational models—to the extent that they are capable of performing successful analogical reasoning—challenge the idea that a successful model of analogical reasoning must take the form of a set of quasi-logical criteria. Efforts to develop a quasi-logical theory of analogical reasoning, it might be argued, have failed. In place of faulty inference schemes such as those described earlier ( §2.2 , §2.4 ), computational models substitute procedures that can be judged on their performance rather than on traditional philosophical standards.

In response to this argument, we should recognize the value of the connectionist models while acknowledging that we still need a theory that offers normative principles for evaluating analogical arguments. In the first place, even if the construction and recognition of analogies are largely a matter of perception, this does not eliminate the need for subsequent critical evaluation of analogical inferences. Second and more importantly, we need to look not just at the construction of analogy mappings but at the ways in which individual analogical arguments are debated in fields such as mathematics, physics, philosophy and the law. These high-level debates require reasoning that bears little resemblance to the computational processes of ACME or Copycat. (Ashley’s HYPO (Ashley 1990) is one example of a non-connectionist program that focuses on this aspect of analogical reasoning.) There is, accordingly, room for both computational and traditional philosophical models of analogical reasoning.

3.5.2 Articulation model

Most prominent theories of analogy, philosophical and computational, are based on overall similarity between source and target domains—defined in terms of some favoured subset of Hesse’s horizontal relations (see §2.2 ). Aristotle and Mill, whose approach is echoed in textbook discussions, suggest counting similarities. Hesse’s theory ( §3.3 ) favours “pre-theoretic” correspondences. The structure-mapping theory and its successors ( §3.4 ) look to systematicity, i.e., to correspondences involving complex, high-level networks of relations. In each of these approaches, the problem is twofold: overall similarity is not a reliable guide to plausibility, and it fails to explain the plausibility of any analogical argument.

Bartha’s articulation model (2010) proposes a different approach, beginning not with horizontal relations, but rather with a classification of analogical arguments on the basis of the vertical relations within each domain. The fundamental idea is that a good analogical argument must satisfy two conditions:

Prior Association . There must be a clear connection, in the source domain, between the known similarities (the positive analogy) and the further similarity that is projected to hold in the target domain (the hypothetical analogy). This relationship determines which features of the source are critical to the analogical inference.

Potential for Generalization . There must be reason to think that the same kind of connection could obtain in the target domain. More pointedly: there must be no critical disanalogy between the domains.

The first order of business is to make the prior association explicit. The standards of explicitness vary depending on the nature of this association (causal relation, mathematical proof, functional relationship, and so forth). The two general principles are fleshed out via a set of subordinate models that allow us to identify critical features and hence critical disanalogies.

To see how this works, consider Example 7 (Rectangles and boxes). In this analogical argument, the source domain is two-dimensional geometry: we know that of all rectangles with a fixed perimeter, the square has maximum area. The target domain is three-dimensional geometry: by analogy, we conjecture that of all boxes with a fixed surface area, the cube has maximum volume. This argument should be evaluated not by counting similarities, looking to pre-theoretic resemblances between rectangles and boxes, or constructing connectionist representations of the domains and computing a systematicity score for possible mappings. Instead, we should begin with a precise articulation of the prior association in the source domain, which amounts to a specific proof for the result about rectangles. We should then identify, relative to that proof, the critical features of the source domain: namely, the concepts and assumptions used in the proof. Finally, we should assess the potential for generalization: whether, in the three-dimensional setting, those critical features are known to lack analogues in the target domain. The articulation model is meant to reflect the conversations that can and do take place between an advocate and a critic of an analogical argument.

3.6.1 Norton’s material theory of analogy

As noted in §2.4 , Norton rejects analogical inference rules. But even if we agree with Norton on this point, we might still be interested in having an account that gives us guidelines for evaluating analogical arguments. How does Norton’s approach fare on this score?

According to Norton, each analogical argument is warranted by local facts that must be investigated and justified empirically. First, there is “the fact of the analogy”: in practice, a low-level uniformity that embraces both the source and target systems. Second, there are additional factual properties of the target system which, when taken together with the uniformity, warrant the analogical inference. Consider Galileo’s famous inference ( Example 12 ) that there are mountains on the moon (Galileo 1610). Through his newly invented telescope, Galileo observed points of light on the moon ahead of the advancing edge of sunlight. Noting that the same thing happens on earth when sunlight strikes the mountains, he concluded that there must be mountains on the moon and even provided a reasonable estimate of their height. In this example, Norton tells us, the the fact of the analogy is that shadows and other optical phenomena are generated in the same way on the earth and on the moon; the additional fact about the target is the existence of points of light ahead of the advancing edge of sunlight on the moon.

What are the implications of Norton’s material theory when it comes to evaluating analogical arguments? The fact of the analogy is a local uniformity that powers the inference. Norton’s theory works well when such a uniformity is patent or naturally inferred. It doesn’t work well when the uniformity is itself the target (rather than the driver ) of the inference. That happens with explanatory analogies such as Example 5 (the Acoustical Analogy ), and mathematical analogies such as Example 7 ( Rectangles and Boxes ). Similarly, the theory doesn’t work well when the underlying uniformity is unclear, as in Example 2 ( Life on other Planets ), Example 4 ( Clay Pots ), and many other cases. In short, if Norton’s theory is accepted, then for most analogical arguments there are no useful evaluation criteria.

3.6.2 Field-specific criteria

For those who sympathize with Norton’s skepticism about universal inductive schemes and theories of analogical reasoning, yet recognize that his approach may be too local, an appealing strategy is to move up one level. We can aim for field-specific “working logics” (Toulmin 1958; Wylie and Chapman 2016; Reiss 2015). This approach has been adopted by philosophers of archaeology, evolutionary biology and other historical sciences (Wylie and Chapman 2016; Currie 2013; Currie 2016; Currie 2018). In place of schemas, we find ‘toolkits’, i.e., lists of criteria for evaluating analogical reasoning.

For example, Currie (2016) explores in detail the use of ethnographic analogy ( Example 13 ) between shamanistic motifs used by the contemporary San people and similar motifs in ancient rock art, found both among ancestors of the San (direct historical analogy) and in European rock art (indirect historical analogy). Analogical arguments support the hypothesis that in each of these cultures, rock art symbolizes hallucinogenic experiences. Currie examines criteria that focus on assumptions about stability of cultural traits and environment-culture relationships. Currie (2016, 2018) and Wylie (Wylie and Chapman 2016) also stress the importance of robustness reasoning that combines analogical arguments of moderate strength with other forms of evidence to yield strong conclusions.

Practice-based approaches can thus yield specific guidelines unlikely to be matched by any general theory of analogical reasoning. One caveat is worth mentioning. Field-specific criteria for ethnographic analogy are elicited against a background of decades of methodological controversy (Wylie and Chapman 2016). Critics and defenders of ethnographic analogy have appealed to general models of scientific method (e.g., hypothetico-deductive method or Bayesian confirmation). To advance the methodological debate, practice-based approaches must either make connections to these general models or explain why the lack of any such connection is unproblematic.

3.6.3 Formal analogies in physics

Close attention to analogical arguments in practice can also provide valuable challenges to general ideas about analogical inference. In an interesting discussion, Steiner (1989, 1998) suggests that many of the analogies that played a major role in early twentieth-century physics count as “Pythagorean.” The term is meant to connote mathematical mysticism: a “Pythagorean” analogy is a purely formal analogy, one founded on mathematical similarities that have no known physical basis at the time it is proposed. One example is Schrödinger’s use of analogy ( Example 14 ) to “guess” the form of the relativistic wave equation. In Steiner’s view, Schrödinger’s reasoning relies upon manipulations and substitutions based on purely mathematical analogies. Steiner argues that the success, and even the plausibility, of such analogies “evokes, or should evoke, puzzlement” (1989: 454). Both Hesse (1966) and Bartha (2010) reject the idea that a purely formal analogy, with no physical significance, can support a plausible analogical inference in physics. Thus, Steiner’s arguments provide a serious challenge.

Bartha (2010) suggests a response: we can decompose Steiner’s examples into two or more steps, and then establish that at least one step does, in fact, have a physical basis. Fraser (forthcoming), however, offers a counterexample that supports Steiner’s position. Complex analogies between classical statistical mechanics (CSM) and quantum field theory (QFT) have played a crucial role in the development and application of renormalization group (RG) methods in both theories ( Example 15 ). Fraser notes substantial physical disanalogies between CSM and QFT, and concludes that the reasoning is based entirely on formal analogies.

4. Philosophical foundations for analogical reasoning

What philosophical basis can be provided for reasoning by analogy? What justification can be given for the claim that analogical arguments deliver plausible conclusions? There have been several ideas for answering this question. One natural strategy assimilates analogical reasoning to some other well-understood argument pattern, a form of deductive or inductive reasoning ( §4.1 , §4.2 ). A few philosophers have explored the possibility of a priori justification ( §4.3 ). A pragmatic justification may be available for practical applications of analogy, notably in legal reasoning ( §4.4 ).

Any attempt to provide a general justification for analogical reasoning faces a basic dilemma. The demands of generality require a high-level formulation of the problem and hence an abstract characterization of analogical arguments, such as schema (4). On the other hand, as noted previously, many analogical arguments that conform to schema (4) are bad arguments. So a general justification of analogical reasoning cannot provide support for all arguments that conform to (4), on pain of proving too much. Instead, it must first specify a subset of putatively ‘good’ analogical arguments, and link the general justification to this specified subset. The problem of justification is linked to the problem of characterizing good analogical arguments . This difficulty afflicts some of the strategies described in this section.

Analogical reasoning may be cast in a deductive mold. If successful, this strategy neatly solves the problem of justification. A valid deductive argument is as good as it gets.

An early version of the deductivist approach is exemplified by Aristotle’s treatment of the argument from example ( §3.2 ), the paradeigma . On this analysis, an analogical argument between source domain \(S\) and target \(T\) begins with the assumption of positive analogy \(P(S)\) and \(P(T)\), as well as the additional information \(Q(S)\). It proceeds via the generalization \(\forall x(P(x) \supset Q(x))\) to the conclusion: \(Q(T)\). Provided we can treat that intermediate generalization as an independent premise, we have a deductively valid argument. Notice, though, that the existence of the generalization renders the analogy irrelevant. We can derive \(Q(T)\) from the generalization and \(P(T)\), without any knowledge of the source domain. The literature on analogy in argumentation theory ( §2.2 ) offers further perspectives on this type of analysis, and on the question of whether analogical arguments are properly characterized as deductive.

Some recent analyses follow Aristotle in treating analogical arguments as reliant upon extra (sometimes tacit) premises, typically drawn from background knowledge, that convert the inference into a deductively valid argument––but without making the source domain irrelevant. Davies and Russell introduce a version that relies upon what they call determination rules (Russell 1986; Davies and Russell 1987; Davies 1988). Suppose that \(Q\) and \(P_1 , \ldots ,P_m\) are variables, and we have background knowledge that the value of \(Q\) is determined by the values of \(P_1 , \ldots ,P_m\). In the simplest case, where \(m = 1\) and both \(P\) and \(Q\) are binary Boolean variables, this reduces to

i.e., whether or not \(P\) holds determines whether or not \(Q\) holds. More generally, the form of a determination rule is

i.e., \(Q\) is a function of \(P_1,\ldots\), \(P_m\). If we assume such a rule as part of our background knowledge, then an analogical argument with conclusion \(Q(T)\) is deductively valid. More precisely, and allowing for the case where \(Q\) is not a binary variable: if we have such a rule, and also premises stating that the source \(S\) agrees with the target \(T\) on all of the values \(P_i\), then we may validly infer that \(Q(T) = Q(S)\).

The “determination rule” analysis provides a clear and simple justification for analogical reasoning. Note that, in contrast to the Aristotelian analysis via the generalization \(\forall x(P(x) \supset Q(x))\), a determination rule does not trivialize the analogical argument. Only by combining the rule with information about the source domain can we derive the value of \(Q(T)\). To illustrate by adapting one of the examples given by Russell and Davies ( Example 16 ), let’s suppose that the value \((Q)\) of a used car (relative to a particular buyer) is determined by its year, make, mileage, condition, color and accident history (the variables \(P_i)\). It doesn’t matter if one or more of these factors are redundant or irrelevant. Provided two cars are indistinguishable on each of these points, they will have the same value. Knowledge of the source domain is necessary; we can’t derive the value of the second car from the determination rule alone. Weitzenfeld (1984) proposes a variant of this approach, advancing the slightly more general thesis that analogical arguments are deductive arguments with a missing (enthymematic) premise that amounts to a determination rule.

Do determination rules give us a solution to the problem of providing a justification for analogical arguments? In general: no. Analogies are commonly applied to problems such as Example 8 ( morphine and meperidine ), where we are not even aware of all relevant factors, let alone in possession of a determination rule. Medical researchers conduct drug tests on animals without knowing all attributes that might be relevant to the effects of the drug. Indeed, one of the main objectives of such testing is to guard against reactions unanticipated by theory. On the “determination rule” analysis, we must either limit the scope of such arguments to cases where we have a well-supported determination rule, or focus attention on formulating and justifying an appropriate determination rule. For cases such as animal testing, neither option seems realistic.

Recasting analogy as a deductive argument may help to bring out background assumptions, but it makes little headway with the problem of justification. That problem re-appears as the need to state and establish the plausibility of a determination rule, and that is at least as difficult as justifying the original analogical argument.

Some philosophers have attempted to portray, and justify, analogical reasoning in terms of some well-understood inductive argument pattern. There have been three moderately popular versions of this strategy. The first treats analogical reasoning as generalization from a single case. The second treats it as a kind of sampling argument. The third recognizes the argument from analogy as a distinctive form, but treats past successes as evidence for future success.

4.2.1 Single-case induction

Let’s reconsider Aristotle’s argument from example or paradeigma ( §3.2 ), but this time regard the generalization as justified via induction from a single case (the source domain). Can such a simple analysis of analogical arguments succeed? In general: no.

A single instance can sometimes lead to a justified generalization. Cartwright (1992) argues that we can sometimes generalize from a single careful experiment, “where we have sufficient control of the materials and our knowledge of the requisite background assumptions is secure” (51). Cartwright thinks that we can do this, for example, in experiments with compounds that have stable “Aristotelian natures.” In a similar spirit, Quine (1969) maintains that we can have instantial confirmation when dealing with natural kinds.

Even if we accept that there are such cases, the objection to understanding all analogical arguments as single-case induction is obvious: the view is simply too restrictive. Most analogical arguments will not meet the requisite conditions. We may not know that we are dealing with a natural kind or Aristotelian nature when we make the analogical argument. We may not know which properties are essential. An insistence on the ‘single-case induction’ analysis of analogical reasoning is likely to lead to skepticism (Agassi 1964, 1988).

Interpreting the argument from analogy as single-case induction is also counter-productive in another way. The simplistic analysis does nothing to advance the search for criteria that help us to distinguish between relevant and irrelevant similarities, and hence between good and bad analogical arguments.

4.2.2 Sampling arguments

On the sampling conception of analogical arguments, acknowledged similarities between two domains are treated as statistically relevant evidence for further similarities. The simplest version of the sampling argument is due to Mill (1843/1930). An argument from analogy, he writes, is “a competition between the known points of agreement and the known points of difference.” Agreement of \(A\) and \(B\) in 9 out of 10 properties implies a probability of 0.9 that \(B\) will possess any other property of \(A\): “we can reasonably expect resemblance in the same proportion” (367). His only restriction has to do with sample size: we must be relatively knowledgeable about both \(A\) and \(B\). Mill saw no difficulty in using analogical reasoning to infer characteristics of newly discovered species of plants or animals, given our extensive knowledge of botany and zoology. But if the extent of unascertained properties of \(A\) and \(B\) is large, similarity in a small sample would not be a reliable guide; hence, Mill’s dismissal of Reid’s argument about life on other planets ( Example 2 ).

The sampling argument is presented in more explicit mathematical form by Harrod (1956). The key idea is that the known properties of \(S\) (the source domain) may be considered a random sample of all \(S\)’s properties—random, that is, with respect to the attribute of also belonging to \(T\) (the target domain). If the majority of known properties that belong to \(S\) also belong to \(T\), then we should expect most other properties of \(S\) to belong to \(T\), for it is unlikely that we would have come to know just the common properties. In effect, Harrod proposes a binomial distribution, modeling ‘random selection’ of properties on random selection of balls from an urn.

There are grave difficulties with Harrod’s and Mill’s analyses. One obvious difficulty is the counting problem : the ‘population’ of properties is poorly defined. How are we to count similarities and differences? The ratio of shared to total known properties varies dramatically according to how we do this. A second serious difficulty is the problem of bias : we cannot justify the assumption that the sample of known features is random. In the case of the urn, the selection process is arranged so that the result of each choice is not influenced by the agent’s intentions or purposes, or by prior choices. By contrast, the presentation of an analogical argument is always partisan. Bias enters into the initial representation of similarities and differences: an advocate of the argument will highlight similarities, while a critic will play up differences. The paradigm of repeated selection from an urn seems totally inappropriate. Additional variations of the sampling approach have been developed (e.g., Russell 1988), but ultimately these versions also fail to solve either the counting problem or the problem of bias.

4.2.3 Argument from past success

Section 3.6 discussed Steiner’s view that appeal to ‘Pythagorean’ analogies in physics “evokes, or should evoke, puzzlement” (1989: 454). Liston (2000) offers a possible response: physicists are entitled to use Pythagorean analogies on the basis of induction from their past success:

[The scientist] can admit that no one knows how [Pythagorean] reasoning works and argue that the very fact that similar strategies have worked well in the past is already reason enough to continue pursuing them hoping for success in the present instance. (200)

Setting aside familiar worries about arguments from success, the real problem here is to determine what counts as a similar strategy. In essence, that amounts to isolating the features of successful Pythagorean analogies. As we have seen (§2.4), nobody has yet provided a satisfactory scheme that characterizes successful analogical arguments, let alone successful Pythagorean analogical arguments.

An a priori approach traces the validity of a pattern of analogical reasoning, or of a particular analogical argument, to some broad and fundamental principle. Three such approaches will be outlined here.

The first is due to Keynes (1921). Keynes appeals to his famous Principle of the Limitation of Independent Variety, which he articulates as follows:

Armed with this Principle and some additional assumptions, Keynes is able to show that in cases where there is no negative analogy , knowledge of the positive analogy increases the (logical) probability of the conclusion. If there is a non-trivial negative analogy, however, then the probability of the conclusion remains unchanged, as was pointed out by Hesse (1966). Those familiar with Carnap’s theory of logical probability will recognize that in setting up his framework, Keynes settled on a measure that permits no learning from experience.

Hesse offers a refinement of Keynes’s strategy, once again along Carnapian lines. In her (1974), she proposes what she calls the Clustering Postulate : the assumption that our epistemic probability function has a built-in bias towards generalization. The objections to such postulates of uniformity are well-known (see Salmon 1967), but even if we waive them, her argument fails. The main objection here—which also applies to Keynes—is that a purely syntactic axiom such as the Clustering Postulate fails to discriminate between analogical arguments that are good and those that are clearly without value (according to Hesse’s own material criteria, for example).

A different a priori strategy, proposed by Bartha (2010), limits the scope of justification to analogical arguments that satisfy tentative criteria for ‘good’ analogical reasoning. The criteria are those specified by the articulation model ( §3.5 ). In simplified form, they require the existence of non-trivial positive analogy and no known critical disanalogy. The scope of Bartha’s argument is also limited to analogical arguments directed at establishing prima facie plausibility, rather than degree of probability.

Bartha’s argument rests on a principle of symmetry reasoning articulated by van Fraassen (1989: 236): “problems which are essentially the same must receive essentially the same solution.” A modal extension of this principle runs roughly as follows: if problems might be essentially the same, then they might have essentially the same solution. There are two modalities here. Bartha argues that satisfaction of the criteria of the articulation model is sufficient to establish the modality in the antecedent, i.e., that the source and target domains ‘might be essentially the same’ in relevant respects. He further suggests that prima facie plausibility provides a reasonable reading of the modality in the consequent, i.e., that the problems in the two domains ‘might have essentially the same solution.’ To call a hypothesis prima facie plausible is to elevate it to the point where it merits investigation, since it might be correct.

The argument is vulnerable to two sorts of concerns. First, there are questions about the interpretation of the symmetry principle. Second, there is a residual worry that this justification, like all the others, proves too much. The articulation model may be too vague or too permissive.

Arguably, the most promising available defense of analogical reasoning may be found in its application to case law (see Precedent and Analogy in Legal Reasoning ). Judicial decisions are based on the verdicts and reasoning that have governed relevantly similar cases, according to the doctrine of stare decisis (Levi 1949; Llewellyn 1960; Cross and Harris 1991; Sunstein 1993). Individual decisions by a court are binding on that court and lower courts; judges are obligated to decide future cases ‘in the same way.’ That is, the reasoning applied in an individual decision, referred to as the ratio decidendi , must be applied to similar future cases (see Example 10 ). In practice, of course, the situation is extremely complex. No two cases are identical. The ratio must be understood in the context of the facts of the original case, and there is considerable room for debate about its generality and its applicability to future cases. If a consensus emerges that a past case was wrongly decided, later judgments will distinguish it from new cases, effectively restricting the scope of the ratio to the original case.

The practice of following precedent can be justified by two main practical considerations. First, and above all, the practice is conservative : it provides a relatively stable basis for replicable decisions. People need to be able to predict the actions of the courts and formulate plans accordingly. Stare decisis serves as a check against arbitrary judicial decisions. Second, the practice is still reasonably progressive : it allows for the gradual evolution of the law. Careful judges distinguish bad decisions; new values and a new consensus can emerge in a series of decisions over time.

In theory, then, stare decisis strikes a healthy balance between conservative and progressive social values. This justification is pragmatic. It pre-supposes a common set of social values, and links the use of analogical reasoning to optimal promotion of those values. Notice also that justification occurs at the level of the practice in general; individual analogical arguments sometimes go astray. A full examination of the nature and foundations for stare decisis is beyond the scope of this entry, but it is worth asking the question: might it be possible to generalize the justification for stare decisis ? Is a parallel pragmatic justification available for analogical arguments in general?

Bartha (2010) offers a preliminary attempt to provide such a justification by shifting from social values to epistemic values. The general idea is that reasoning by analogy is especially well suited to the attainment of a common set of epistemic goals or values. In simple terms, analogical reasoning—when it conforms to certain criteria—achieves an excellent (perhaps optimal) balance between the competing demands of stability and innovation. It supports both conservative epistemic values, such as simplicity and coherence with existing belief, and progressive epistemic values, such as fruitfulness and theoretical unification (McMullin (1993) provides a classic list).

5. Beyond analogical arguments

As emphasized earlier, analogical reasoning takes in a great deal more than analogical arguments. In this section, we examine two broad contexts in which analogical reasoning is important.

The first, still closely linked to analogical arguments, is the confirmation of scientific hypotheses. Confirmation is the process by which a scientific hypothesis receives inductive support on the basis of evidence (see evidence , confirmation , and Bayes’ Theorem ). Confirmation may also signify the logical relationship of inductive support that obtains between a hypothesis \(H\) and a proposition \(E\) that expresses the relevant evidence. Can analogical arguments play a role, either in the process or in the logical relationship? Arguably yes (to both), but this role has to be delineated carefully, and several obstacles remain in the way of a clear account.

The second context is conceptual and theoretical development in cutting-edge scientific research. Analogies are used to suggest possible extensions of theoretical concepts and ideas. The reasoning is linked to considerations of plausibility, but there is no straightforward analysis in terms of analogical arguments.

How is analogical reasoning related to the confirmation of scientific hypotheses? The examples and philosophical discussion from earlier sections suggest that a good analogical argument can indeed provide support for a hypothesis. But there are good reasons to doubt the claim that analogies provide actual confirmation.

In the first place, there is a logical difficulty. To appreciate this, let us concentrate on confirmation as a relationship between propositions. Christensen (1999: 441) offers a helpful general characterization:

Some propositions seem to help make it rational to believe other propositions. When our current confidence in \(E\) helps make rational our current confidence in \(H\), we say that \(E\) confirms \(H\).

In the Bayesian model, ‘confidence’ is represented in terms of subjective probability. A Bayesian agent starts with an assignment of subjective probabilities to a class of propositions. Confirmation is understood as a three-place relation:

\(E\) represents a proposition about accepted evidence, \(H\) stands for a hypothesis, \(K\) for background knowledge and \(Pr\) for the agent’s subjective probability function. To confirm \(H\) is to raise its conditional probability, relative to \(K\). The shift from prior probability \(Pr(H \mid K)\) to posterior probability \(Pr(H \mid E \cdot K)\) is referred to as conditionalization on \(E\). The relation between these two probabilities is typically given by Bayes’ Theorem (setting aside more complex forms of conditionalization):

For Bayesians, here is the logical difficulty: it seems that an analogical argument cannot provide confirmation. In the first place, it is not clear that we can encapsulate the information contained in an analogical argument in a single proposition, \(E\). Second, even if we can formulate a proposition \(E\) that expresses that information, it is typically not appropriate to treat it as evidence because the information contained in \(E\) is already part of the background, \(K\). This means that \(E \cdot K\) is equivalent to \(K\), and hence \(Pr(H \mid E \cdot K) = Pr(H \mid K)\). According to the Bayesian definition, we don’t have confirmation. (This is a version of the problem of old evidence; see confirmation .) Third, and perhaps most important, analogical arguments are often applied to novel hypotheses \(H\) for which the prior probability \(Pr(H \mid K)\) is not even defined. Again, the definition of confirmation in terms of Bayesian conditionalization seems inapplicable.

If analogies don’t provide inductive support via ordinary conditionalization, is there an alternative? Here we face a second difficulty, once again most easily stated within a Bayesian framework. Van Fraassen (1989) has a well-known objection to any belief-updating rule other than conditionalization. This objection applies to any rule that allows us to boost credences when there is no new evidence. The criticism, made vivid by the tale of Bayesian Peter, is that these ‘ampliative’ rules are vulnerable to a Dutch Book . Adopting any such rule would lead us to acknowledge as fair a system of bets that foreseeably leads to certain loss. Any rule of this type for analogical reasoning appears to be vulnerable to van Fraassen’s objection.

There appear to be at least three routes to avoiding these difficulties and finding a role for analogical arguments within Bayesian epistemology. First, there is what we might call minimal Bayesianism . Within the Bayesian framework, some writers (Jeffreys 1973; Salmon 1967, 1990; Shimony 1970) have argued that a ‘seriously proposed’ hypothesis must have a sufficiently high prior probability to allow it to become preferred as the result of observation. Salmon has suggested that analogical reasoning is one of the most important means of showing that a hypothesis is ‘serious’ in this sense. If analogical reasoning is directed primarily towards prior probability assignments, it can provide inductive support while remaining formally distinct from confirmation, avoiding the logical difficulties noted above. This approach is minimally Bayesian because it provides nothing more than an entry point into the Bayesian apparatus, and it only applies to novel hypotheses. An orthodox Bayesian, such as de Finetti (de Finetti and Savage 1972, de Finetti 1974), might have no problem in allowing that analogies play this role.

The second approach is liberal Bayesianism : we can change our prior probabilities in a non-rule-based fashion . Something along these lines is needed if analogical arguments are supposed to shift opinion about an already existing hypothesis without any new evidence. This is common in fields such as archaeology, as part of a strategy that Wylie refers to as “mobilizing old data as new evidence” (Wylie and Chapman 2016: 95). As Hawthorne (2012) notes, some Bayesians simply accept that both initial assignments and ongoing revision of prior probabilities (based on plausibility arguments) can be rational, but

the logic of Bayesian induction (as described here) has nothing to say about what values the prior plausibility assessments for hypotheses should have; and it places no restrictions on how they might change.

In other words, by not stating any rules for this type of probability revision, we avoid the difficulties noted by van Fraassen. This approach admits analogical reasoning into the Bayesian tent, but acknowledges a dark corner of the tent in which rationality operates without any clear rules.

Recently, a third approach has attracted interest: analogue confirmation or confirmation via analogue simulation . As described in (Dardashti et al. 2017), the idea is as follows:

Our key idea is that, in certain circumstances, predictions concerning inaccessible phenomena can be confirmed via an analogue simulation in a different system. (57)

Dardashti and his co-authors concentrate on a particular example ( Example 17 ): ‘dumb holes’ and other analogues to gravitational black holes (Unruh 1981; Unruh 2008). Unlike real black holes, some of these analogues can be (and indeed have been) implemented and studied in the lab. Given the exact formal analogy between our models for these systems and our models of black holes, and certain important additional assumptions, Dardashti et al. make the controversial claim that observations made about the analogues provide evidence about actual black holes. For instance, the observation of phenomena analogous to Hawking radiation in the analogue systems would provide confirmation for the existence of Hawking radiation in black holes. In a second paper (Dardashti et al. 2018, Other Internet Resources), the case for confirmation is developed within a Bayesian framework.

The appeal of a clearly articulated mechanism for analogue confirmation is obvious. It would provide a tool for exploring confirmation of inaccessible phenomena not just in cosmology, but also in historical sciences such as archaeology and evolutionary biology, and in areas of medical science where ethical constraints rule out experiments on human subjects. Furthermore, as noted by Dardashti et al., analogue confirmation relies on new evidence obtained from the analogue system, and is therefore not vulnerable to the logical difficulties noted above.

Although the concept of analogue confirmation is not entirely new (think of animal testing, as in Example 8 ), the claims of (Dardashti et al. 2017, 2018 [Other Internet Resources]) require evaluation. One immediate difficulty for the black hole example: if we think in terms of ordinary analogical arguments, there is no positive analogy because, to put it simply, we have no basis of known similarities between a ‘dumb hole’ and a black hole. As Crowther et al. (2018, Other Internet Resources) argue, “it is not known if the particular modelling framework used in the derivation of Hawking radiation actually describes black holes in the first place. ” This may not concern Dardashti et al., since they claim that analogue confirmation is distinct from ordinary analogical arguments. It may turn out that analogue confirmation is different for cases such as animal testing, where we have a basis of known similarities, and for cases where our only access to the target domain is via a theoretical model.

In §3.6 , we saw that practice-based studies of analogy provide insight into the criteria for evaluating analogical arguments. Such studies also point to dynamical or programmatic roles for analogies, which appear to require evaluative frameworks that go beyond those developed for analogical arguments.

Knuttila and Loettgers (2014) examine the role of analogical reasoning in synthetic biology, an interdisciplinary field that draws on physics, chemistry, biology, engineering and computational science. The main role for analogies in this field is not the construction of individual analogical arguments but rather the development of concepts such as “noise” and “feedback loops”. Such concepts undergo constant refinement, guided by both positive and negative analogies to their analogues in engineered and physical systems. Analogical reasoning here is “transient, heterogeneous, and programmatic” (87). Negative analogies, seen as problematic obstacles for individual analogical arguments, take on a prominent and constructive role when the focus is theoretical construction and concept refinement.

Similar observations apply to analogical reasoning in its application to another cutting-edge field: emergent gravity. In this area of physics, distinct theoretical approaches portray gravity as emerging from different microstructures (Linneman and Visser 2018). “Novel and robust” features not present at the micro-level emerge in the gravitational theory. Analogies with other emergent phenomena, such as hydrodynamics and thermodynamics, are exploited to shape these proposals. As with synthetic biology, analogical reasoning is not directed primarily towards the formulation and assessment of individual arguments. Rather, its role is to develop different theoretical models of gravity.

These studies explore fluid and creative applications of analogy to shape concepts on the front lines of scientific research. An adequate analysis would certainly take us beyond the analysis of individual analogical arguments, which have been the focus of our attention. Knuttila and Loettgers (2014) are led to reject the idea that the individual analogical argument is the “primary unit” in analogical reasoning, but this is a debatable conclusion. Linneman and Visser (2018), for instance, explicitly affirm the importance of assessing the case for different gravitational models through “exemplary analogical arguments”:

We have taken up the challenge of making explicit arguments in favour of an emergent gravity paradigm… That arguments can only be plausibility arguments at the heuristic level does not mean that they are immune to scrutiny and critical assessment tout court. The philosopher of physics’ job in the process of discovery of quantum gravity… should amount to providing exactly this kind of assessments. (Linneman and Visser 2018: 12)

Accordingly, Linneman and Visser formulate explicit analogical arguments for each model of emergent gravity, and assess them using familiar criteria for evaluating individual analogical arguments. Arguably, even the most ambitious heuristic objectives still depend upon considerations of plausibility that benefit by being expressed, and examined, in terms of analogical arguments.

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Other Internet Resources

• Crowther, K., N. Linnemann, and C. Wüthrich, 2018, “ What we cannot learn from analogue experiments ,” online at arXiv.org.
• Dardashti, R., S. Hartmann, K. Thébault, and E. Winsberg, 2018, “ Hawking Radiation and Analogue Experiments: A Bayesian Analysis ,” online at PhilSci Archive.
• Norton, J., 2018. “ Analogy ”, unpublished draft, University of Pittsburgh.
• Resources for Research on Analogy: a Multi-Disciplinary Guide (University of Windsor)
• UCLA Reasoning Lab (UCLA)
• Dedre Gentner’s publications (Northwestern University)
• The Center for Research on Concepts and Cognition (Indiana University)

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• Scriptwriting

What is an Analogy — Definition, Examples in Literature & Film

A ll writers aim to engage their audience. And to engage their audience, their writing must be effective. So what are the tricks of the trade to effective writing? There are various elements to great writing, but two fundamental elements are clear communication of ideas and conciseness. One of the best tools a writer has to achieve both is analogy.  In this article, we’ll define analogy and distinguish it from other literary devices. We’ll also take a look at some analogy examples in some of the most iconic lines in literature and film and how it has contributed to both. 

Tools For Screenwriters

Literary devices.

          Literary Elements

• Deuteragonist
• Foil Character
• Point of View
• Protagonist

          Literary Techniques

• Alliteration
• Connotation
• Deus ex Machina
• Foreshadowing
• Iambic Pentameter
• Juxtaposition
• Onomatopoeia
• Personification
• Red Herring

What is Analogy in Literature 

First, let’s define analogy.

Analogies have an overlap with other literary devices such as metaphors and similes. To better distinguish analogy, let’s take a look at the analogy literary definition. 

ANALOGY LITERARY DEFINITION

What is analogy in literature.

An analogy is a literary device used to compare similarities between two unrelated things as a way to make a point through the comparison. Analogies are primarily used to identify similar relationships or to identify similar abstractions between two things or ideas. Analogies are often mistaken for similes and metaphors. While they are similar, analogies differ in that they aim to make a logical argument by showing similarities between two dissimilar things. Analogies can utilize similes or metaphors but are further elaborated on to support in argument or claim. 

What is analogy used for?

• Creating a persuasive argument
• Making abstract ideas more concrete
• Relating to the audience or reader

What Does Analogy Mean in Literature?

Analogy vs. metaphor vs. simile.

An analogy is often mixed up with other literary devices like metaphors and similes . Although they all share similarities to one another in that they compare two unlike things, they differ in specific ways. 

• Creates a relationship based on similarities between two ideas
• Generally a longer comparison, more than a sentence
• More elaborate or extensive than a simile
• Compares two objects with connecting words
• Generally a shorter comparison, like in a single sentence
• More simple and basic than an analogy

Similes compare the similarities between two unlike things using the words “like” or “as.” For example, “Life is like a mountain.”

A metaphor is a literary device used to say something  is  something else. It allows the reader to do further interpretation. For example, “Life is a mountain.”

An analogy is a comparison between two things with the goal to make a larger point. For example, “Life is like a mountain. Hard to climb, but the view at the top is worth it.” This further explanation, stated or not, is what distinguishes an analogy. Metaphors and similes can be used within  an analogy to drive the point home. 

ANALOGY MEANING IN LITERATURE

It is not uncommon for writers to find difficulty in communicating ideas both abstract and literal to their audience. Learning how to write analogies will help you as a writer tackle these obstacles. Communicating these ideas effectively can be the difference in writing an engaging novel, a persuasive argument, or an effective explanation. 

1. Support an argument

In forms other than traditional literature such as essays, critiques, or analyses, analogies can be an effective tool at making a persuasive argument. This is often used in counter arguments to negate the logic of another claim. 

2. Make abstract concepts relatable

One of the more difficult tasks writers have is being concise when explaining or communicating abstract ideas. Analogies can be extremely effective at making abstract ideas more concrete. They do this by including something relatable within analogies that audiences can understand and latch onto. 

For example, the idea of raising a child is rather large and abstract. Let’s take a look at an example that can explain what raising a child is like using something relatable. “Raising a child is like gardening. It takes both patience and practice.” By using gardening within the analogy, readers can better understand what the author is trying to say about parenting. 

3. Add depth to imagery and emotions

In literature, analogies are commonly used to add depth to the imagery of the story. Literal writing has its own limitations that can inhibit an audience's emotional connection to a piece of writing. Analogies address this by relating to the user’s experience to have them better understand the imagery or emotions of the story. 

For example, to say “He loved her very much” is ineffective at communicating the affection a character has for another person. But using analogies and saying “His love for her was as vast and deep as the ocean itself” can better communicate this love because of the reader’s ability to relate to the imagery of the ocean. 

Related Posts

• What is a Simile? Definition and Examples →
• Examples of Metaphors in Film and Why They Matter →
• FREE: Write and create professionally formatted screenplays →

Analyzing Analogy Examples

Analogy examples in literature.

To analyze how analogies are effective at communicating higher concepts effectively and concisely, let’s take a look at William Shakespeare’s iconic Romeo and Juliet . In this moment in the play, Juliet comes to the conclusion that the names Montague and Capulet are irrelevant. No matter the name, Romeo is still the same person, and that’s what matters.

To put this more poetically and in a way that is more relatable, Shakespeare uses an analogy comparing Romeo to a rose. 

‘Tis but thy name that is my enemy;

Thou art thyself, though not a Montague.

What’s Montague? It is nor hand, nor foot,

Nor arm, nor face, nor any other part

Belonging to a man. O, be some other name!

What’s in a name? That which we call a rose

By any other name would smell as sweet;

So Romeo would, were he not Romeo call’d,

Retain that dear perfection which he owes

Without that title. Romeo, doff thy name,

And for that name which is no part of thee

Take all myself.”

— William Shakespeare

The analogy is able to compare a rose, its smell, and its name to Romeo, his character, and his name. Not only does this make the speech romantically poetic, it effectively communicates an abstract idea in a concise, relatable way. 

What Does Analogy Mean in Cinema

Analogy examples in film.

Analogies are used beyond the realm of literature. In filmmaking and screenwriting, analogies are used similarly to communicate ideas in less time. Time is a valuable resource when it comes to film, and using analogies can be effective at saving this resource.

One of the most iconic lines in all of cinema is in fact an analogy. It’s none other than the quote about life from Forrest Gump . We brought the script into StudioBinder's screenwriting software so you can read how this iconic analogy is written on the page. Click the image below to read the entire scene.

Forrest Gump  •  Life is Like a Box of Chocolates analogy examples

In one of the most iconic lines in cinema, Forrest (or rather Forrest’s mom) compares life to the unpredictability of a box of chocolates with the line “Life is like a box of chocolates. You never know what you’re gonna get.”

Not only does this foreshadow the plot that follows this specific line as it follows Forrest’s life, it establishes one of the film’s themes . The relatability and conciseness of this makes it easily memorable and iconic.  

• A Complete Guide to Literary Devices →
• How Writers and Filmmakers Use Motifs →

What is a Simile? With Examples

One of the most common ways to create an analogy is by using a simile. What is the difference between simile and metaphor? How can similes be used other than in an analogy? We answer both of those questions and more in our next article.

Up Next: Similes With Examples →

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• Literary Terms
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• When & How to write an Analogy

I. What is an Analogy?

An analogy is a literary technique in which two unrelated objects are compared for their shared qualities. Unlike a simile or a metaphor, an analogy is not a figure of speech, though the three are often quite similar. Instead, analogies are strong rhetorical devices used to make rational arguments and support ideas by showing connections and comparisons between dissimilar things.

II. Examples of Analogy

Analogies are commonly used to show important comparisons and make solid arguments. Here are some examples:

Every choice you make is like spinning the wheel of fortune—sometimes you will get the result that you desire, while other times you will end up with something you always hoped to avoid.

Raising children requires the same dedication you would give to a garden. Nurture them, feed them, introduce them to both light and dark, and have patience; and soon you will see them grow into blooming wonders.

In the first example, the writer could have said “Every choice has a different consequence.” But like similes, analogies make associations between things that wouldn’t usually be compared (like choices to wheels of fortune and children to gardens). These comparisons create better descriptions and sensory images in the minds of readers. On the other hand, analogies are more elaborate and informational than similes or metaphors , providing support for the comparisons made rather than just stating them as simple truths. As you can see, the second example explains how children and gardens have similar qualities because they require similar growing conditions.

Photosynthesis does for plants what digesting food does for animals. It is the process that lets them convert nutrients into the fuel needed to grow and develop. 

You may also see analogies that compare relationships rather than individual things. But the analogy still works in the same way; it explains how the relationships share a similar quality of transforming nutrients.

III. Types of Analogy

A. literal analogy.

In a literal analogy, you are saying that one thing really is similar to another. This is the kind of analogy that you would draw if you wanted to make an argument  or persuasion. For example, when scientists test a new medicine on laboratory mice, they are arguing that mice and humans really are similar in medically significant ways. Therefore, as the argument goes, if a medicine works on mice, it should also work on humans (or at least it’s ready for human testing).

b. Figurative Analogy

In a figurative analogy, you’re simply drawing a comparison between two unrelated things to highlight a certain characteristic; you’re not necessarily saying that the things are truly similar .  Take, for example, the wheel of fortune example. If life were truly similar to a wheel of fortune you would have a lot less control over our choices and the consequences would be unpredictable.

IV. The Importance of Analogy

As mentioned, analogies are used to make logical arguments and comparisons. Here are a few ways writers might use analogies:

a. Make abstract ideas more concrete

There are some people – like teachers, professors, and technical writers – who explain difficult ideas for a living. It’s a tough job! One way to make it easier is to draw analogies to things your readers or students are already familiar with. For example, a biology teacher might explain the immune system by saying, “What policemen do in a town, white blood cells do inside the body.”

b. Add depth and feeling to an image

Consider this example:

 She felt like a raft floating in the middle of an dark, endless ocean. Like her, the raft was was floating along, alone, worn out, and unable to reach a steady place in which to settle.

Notice what a powerful image this descriptions brings to mind. Without the analogy, the author would just be saying “She was lonely and exhausted.” How boring! The analogy makes her emotions seem dark and overwhelming – just as the ocean at night.

c. Making a persuasive argument

Obviously, this is rare in poetry and fiction, where making an argument isn’t the point. But in essays , literary analysis, and many other fields, persuasion is the name of the game – and analogy can be a powerful tool for that purpose. It’s especially useful when you want to show the flawed reasoning in another person’s argument:

Person A : Lots of history’s dictators started as soldiers; therefore, soldiers should never become politicians because they’ll end up as dictators.

Person B : But that doesn’t make sense! It’s like saying “lots of alcoholics started out by drinking milk; therefore no one should ever drink milk.” Just as there are many milk-drinkers who don’t become alcoholics, there are also many soldiers who don’t become dictators .

Notice how Person B has employed a clever analogy to show that Person A is making a faulty argument.

V. Examples of Analogy in Literature

They crowded very close about him, with their hands always on him in a careful, caressing grip, as though all the while feeling him to make sure he was there. It was like men handling a fish which is still alive and may jump back into the water. (George Orwell, A Hanging)

In this passage, Orwell is describing the crowd’s reaction to seeing a man hanged. One interpretation of the analogies is that they create a supernatural feeling by subtly suggesting the possibility that the dead man may simply disappear, or may suddenly come back to life.

What gunpowder did for war the printing press has done for the mind. (Wendell Phillips, Public Opinion on the Abolition Question)

Gunpowder revolutionized war and brought down old hierarchies and strategies – after the introduction of the gun, war would never be the same. Similarly, the invention of the printing press allowed books and newspapers to reach vast audiences that otherwise had no access to the written word. This revolutionized education and made possible an era of widespread literacy and democratic thought.

“Evolution is a blind giant who rolls a snowball down a hill. The ball is made of flakes—circumstances. They contribute to the mass without knowing it. They adhere without intention, and without foreseeing what is to result. When they see the result they marvel at the monster ball and wonder how the contriving of it came to be originally thought out and planned. Whereas there was no such planning, there was only a law: the ball once started, all the circumstances that happened to lie in its path would help to build it, in spite of themselves.” (Mark Twain, Tales of Wonder)

Here, Twain uses an analogy to speak about evolution, comparing it to a giant rolling a snowball down the hill–the results are quite unpredictable, but inevitable.

VI. Examples of Analogy in Pop Culture

(adsbygoogle = window.adsbygoogle || []).push({}); “My momma always said “life is like a box of chocolates – you never know what you’re gonna get!” (Forrest Gump)

Here, Forrest Gump shares a very memorable analogy, beginning with the simile “life was like a box of chocolates.” But, this is an analogy because it gives further support and explanation for the comparison, showing that life has many choices and surprises, just like a box of chocolate.

Oh, he ‘loved to laugh?’ Well, that doesn’t tell you anything! That’s like saying , ‘He hungered for food! (Patton Oswald, Obituaries)

This is a humorous version of argument by analogy. Oswald, a standup comedian, is poking fun at articles about him by comparing that statement to something obviously commonplace, showing that the argument that he “loved to laugh” is about as strong as saying he gets hungry for food.

People are like stained-glass windows. They sparkle and shine when the sun is out, but when the darkness sets in, their true beauty is revealed only if there is a light from within. (Quote by Elisabeth Kübler-Ross in The Leader’s Digest by Jim Clemmer, 2003)

In this quote, the groundbreaking psychiatrist Elizabeth Kübler-Ross (well-known for her 5 Stages of Grief) gives an analogy about the human condition, saying that people, like stained-glass, work differently in situations of light and dark.

VII. Related Terms

People often confuse analogies with similes and metaphors, which are both figures of speech. However, they are actually very different, specifically because an analogy is a rhetorical device, not a figure of speech. While similes and metaphors are generally quite short and simple, analogies are more elaborate and explanatory, because they support arguments.

A  figure of speech that makes comparisons using explicit “comparing” words such as like or as. So when you see like or as underlined in this article, you know it’s an example of a simile.

“What light through yonder window breaks? It is the East, and Juliet is like the sun!”

“…It is the East, and Juliet is as radiant as the sun!”

A figure of speech where unrelated things are compared – basically, it’s just a simile with the “like” or “as” removed.

“What light through yonder window breaks? It is the East, and Juliet is the sun!” (William Shakespeare, Romeo and Juliet)

It’s important to remember that a metaphor is not a kind of analogy – it’s a different figure of speech altogether. However, it’s very similar to analogy in that they both depend on some kind of similarity between two different objects.

Example of an analogy versus simile and metaphor:

Simile : Life is like a garden.

Metaphor : Life is a garden.

Analogy: Life is just like a garden–it is ever growing and changing, needing care and dedication, and always filled with beautiful surprises.

Again, it’s important to remember that metaphors and similes are figures of speech, while analogies are NOT. However, they are very similar to analogies in that they both depend on some kind of similarity between two different objects.

List of Terms

• Alliteration
• Amplification
• Anachronism
• Anthropomorphism
• Antonomasia
• APA Citation
• Aposiopesis
• Autobiography
• Bildungsroman
• Characterization
• Circumlocution
• Cliffhanger
• Comic Relief
• Connotation
• Deus ex machina
• Deuteragonist
• Doppelganger
• Double Entendre
• Dramatic irony
• Equivocation
• Extended Metaphor
• Figures of Speech
• Flash-forward
• Foreshadowing
• Intertextuality
• Juxtaposition
• Literary Device
• Malapropism
• Onomatopoeia
• Parallelism
• Pathetic Fallacy
• Personification
• Point of View
• Polysyndeton
• Protagonist
• Red Herring
• Rhetorical Device
• Rhetorical Question
• Science Fiction
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• Synesthesia
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Definition of Analogy

An analogy is a figure of speech that creates a comparison by showing how two seemingly different entities are alike, along with illustrating a larger point due to their commonalities. As a literary device, the purpose of analogy is not just to make a comparison, but to provide an explanation as well with additional information or context . This makes analogy a bit more complex than similar literary devices such as metaphor and simile . Analogy is an effective device in terms of providing a new or deeper meaning to concepts through the artistic use of language.

For example, the analogy  nose is to olfactory as ear is to auditory makes a comparison between parts of the body that are related to certain senses and the words to describe the senses themselves. “Olfactory” refers to the sense of smell, which is related to “nose.” “Auditory” refers to the sense of hearing, which is related to “ear.” Of course, the writer could use the analogy  nose is to smell as ear is to hear for a similar comparison. However, the description words of olfactory and auditory create a deeper meaning and sense of the relationship between these parts of the body and the senses.

Common Examples of Analogy

Many people are introduced to analogy as a form of word relationship that demonstrates the associations between two object or concept pairs on the basis of logic or reasoning. The phrasing for these analogies is generally “(first word) is to (second word) as (third word) is to (fourth word)” or “baby is to adult as kitten is to cat.” Here are some common examples of verbal analogies:

• blue is to color as circle is to shape
• eyes are to sight as fingers are to touch
• cub is to bear and calf is to cow
• sand is to beach as water is to ocean
• glove is to hand as sock is to foot
• ripple is to pond as wave is to ocean
• words are to writing as notes are to music
• fish are to aquariums as animals are to zoos
• fingers are to snapping as hands are to clapping
• petal is to flower as leaf is to tree

Famous Examples of Analogy

Think you haven’t heard of any famous analogies? Here are some recognizable examples of this figure of speech by well-known writers and speakers :

• That which we call a rose / By any other name would smell as sweet ( William Shakespeare )
• And I began to let him go. Hour by hour. Days into months. It was a physical sensation, like letting out the string of a kite. Except that the string was coming from my center. (Augusten Burroughs)
• It has been well said that an author who expects results from a first novel is in a position similar to that of a man who drops a rose petal down the Grand Canyon of Arizona and listens for the echo. (P.G. Wodehouse)
• Don’t worry about the future. Or worry, but know that worrying is as effective as trying to solve an algebra equation by chewing bubble gum. (Mary Schmich)
• Confession is good for the soul only in the sense that a tweed coat is good for dandruff – it is a palliative rather than a remedy. (Peter De Vries)
• Withdrawal of U.S. troops will become like salted peanuts to the American public; the more U.S. troops come home, the more will be demanded. (Henry Kissinger)
• People are like stained-glass windows. They sparkle and shine when the sun is out, but when the darkness sets in, their true beauty is revealed only if there is a light from within. (Elisabeth Kubler-Ross)
• A nation wearing atomic armor is like a knight whose armor has grown so heavy he is immobilized; he can hardly walk, hardly sit his horse, hardly think, hardly breathe. The H-bomb is an extremely effective deterrent to war, but it has little virtue as a weapon of war because it would leave the world uninhabitable. (E.B. White)

Examples of Analogy by Thomas Carlyle

Thomas Carlyle was a British writer, historian, philosopher, and mathematician of the 19th Century. His writings often featured analogies that have since appeared in standardized tests of advanced placement English, among others. Carlyle’s analogies are thought-provoking as comparisons and valuable for analysis. Here are some examples:

• Under all speech that is good for anything, there lies a silence that is better. Silence is deep as Eternity; speech is shallow as Time.
• No great man lives in vain. The history of the world is but the biography of great men.
• It has been well said that the highest aim in education is analogous to the highest aim in mathematics, namely, to obtain not results but powers, not particular solutions, but the means by which endless solutions may be wrought.
• What we become depends on what we read after all of the professors have finished with us. The greatest university of all is a collection of books.
• Music is well said to be the speech of angels; in fact, nothing among the utterances allowed to man is felt to be so divine. It brings us near to the infinite.
• The block of granite which was an obstacle in the pathway of the weak becomes a stepping-stone in the pathway of the strong.
• Wondrous is the strength of cheerfulness, and its power of endurance – the cheerful man will do more in the same time, will do it better, will preserve it longer, than the sad or sullen.
• Show me the man you honor, and I will know what kind of man you are.

Difference Between Analogy, Metaphor, and Simile

Analogies, similes, and metaphors are all figures of speech used to create comparisons between different entities. These literary devices are often confused with each other, though they can be distinguished. A simile utilizes the words “like” or “as” to make a comparison. A metaphor uses figurative language to compare two things by stating that one is the other. An analogy creates a comparison with the intent of explanation or indicating a larger point.

Here are some examples to help differentiate between these three literary devices:

• Memory is to love what the saucer is to the cup.– This is an analogy . It explains the abstract relationship between memory and love by making a comparison between the tangible and familiar relationship between a cup and saucer. Though these entities are different in terms of abstract concepts and tangible items, they are alike in the sense that a saucer holds and supports a cup as memory holds and supports love. This analogy provides an interesting image of the relationship between memory and love through the artistic comparison to the saucer and cup.
• Memory and love are like a saucer and cup. –This figure of speech is a Simile . The presence of the word “like” is the basis of the comparison.
• Memory and love are a saucer and cup. –This is an example of a Metaphor . The language used in this metaphor is figurative in the sense that the reader knows that memory and love are not literally a saucer and cup. Instead, the example is making a comparison by linking them directly–that one is the other.

Analogy, simile, and metaphor are all useful and related literary devices for writers to make comparisons. The intention of these devices and their wording is what differentiates them from each other.

Writing Analogy

Overall, as a literary device, analogy functions as a means of comparing entities and enhancing the clarity of one entity through connection with the other. This is effective for readers in that analogies create imagery and a deeper understanding of concepts. Therefore, this can enhance the meaning and understanding of a literary work or theme by using artistic language to present ideas in a new way.

There are two primary types of analogy:

• Identification of identical relationships: Like the word relationships featured above, Greek scholars utilized analogies as direct illustrations of similar relationships between word pairings. These analogies identify identical word relationships based in logic and for the purpose of reasoned argument . They also enhance connections for readers between the meanings of words and concepts.
• Identification of shared abstraction: This type of analogy creates comparisons between two things that appear unrelated but share an attribute or pattern. The purpose of these analogies is to utilize a reader’s current knowledge of something familiar and connect it to an abstract idea so that it is more concrete in comparison.

Writers benefit from incorporating analogies into their work for the purpose of explaining and connecting ideas for their readers. It’s important for writers to understand that an effective analogy is one in which the comparison is logical and easily understood. An analogy that made an unreasonable or illogical comparison would be an improper use of the literary device.

Types of Analogy: Literal and Figurative

There are two types of analogy. One is literal and the other is figurative. In literal analogy, the comparison is literal, as one thing is stated to be similar to the other. It is used for persuasion in an argument. However, the figurative analogy is based on some features and properties. It mostly occurs through metaphors and similes. Both of these figures of speech are used in figurative analogies.

Types of Analogy in Writing

Analogy occurs at two levels in writing. The first one is the comparison of relationships. Two things are set side by side and their relationship is identified through the use of similes. The second analogical writing is about abstract ideas as two ideas are compared with each other by setting them side by side.

Use of Analogy in Sentences

• Searching for a chicken in Granma’s soup is like searching for a turtle in the ocean.
• Abbie’s like a squeaky mouse when she’s on the stage.
• Water is to the lake as lava is to the volcano.
• Pedals are to the bicycle as oars are to the boat.
• Flow is for water as the break is for solid.
• Drive : Steer :: Live : Breathe (A few analogies used for critical thinking are written in this form)

Examples of Analogy in Literature

Analogy is an effective literary device as a method of creating comparisons and developing meaning. Here are some examples of analogy and the way it enhances the significance of well-known literary works:

Example 1: There is no Frigate like a Book by Emily Dickinson

There is No Frigate like a Book To take us Lands away Nor any Coursers like a Page Of prancing Poetry – This Traverse may the poorest take Without oppress of Toll – How frugal is the Chariot That bears the Human Soul –

Example 2: Do Not Go Gentle Into That Good Night by Dylan Thomas

Grave men, near death, who see with blinding sight Blind eyes could blaze like meteors and be gay, Rage, rage against the dying of the light.

In this stanza , Thomas utilizes several literary devices, including metaphor and simile. As a whole, these lines create an analogy for death. “The dying of the light” signifies death, and that moment is compared to both blindness and sight. This creates a deeper meaning as the poet calls for “rage” against this moment to fight against blindness towards the unknown and the clarity of vision that comes with death.

Example 3: A Week on the Concord and Merrimack Rivers by Henry David Thoreau

This world is but a canvas to our imaginations.

In this analogy, Thoreau compares the world to a canvas in terms of human imagination. To a degree, Thoreau could have created a more abstract comparison by stating that the world is but a canvas, which would have implied creativity, art, beauty in nature, and so on. Instead, he provides the added context of imagination. This allows for clarity as to what Thoreau is trying to convey to his readers, yet the analogy is still comprised of artistic and figurative language.

Synonyms of Analogy

Like other literary devices, it has close synonyms such as likeness, similarity, resemblance, or similitude could prove its synonyms.

Related posts:

• Importance of Analogy and How to Write with Examples

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What Is Analogy? Definition, Usage, and Literary Examples

Analogy definition.

An  analogy  (uh-NAHL-uh-gee) is a rhetorical device in which a writer compares the shared qualities of two unrelated objects. They are different from  similes  and  metaphors , which also compare unrelated objects by equating them. However, an analogy can employ either one to drive home its larger point. Analogies support logic, present rational arguments, and back up ideas by showing the relationship between disparate things.

The word  analogy  comes from the Greek  analogia , meaning “proportion,” which builds off  ana , meaning “according to,” and  logos , meaning “ratio.”

How to Construct an Analogy

Most analogies in literature,  rhetoric , and everyday communication contain two components: the unknown concept, which is the target, and the known concept, which is the source. The target is the idea the analogy hopes to explain, while the source is the idea used to explain it. The source is something familiar or widely understood to most people; the target is something unfamiliar and mysterious.

When creating a link between the two concepts, writers are essentially making the unfamiliar into something familiar. For example, take the classic line from  Forrest Gump : “Life is like a box of chocolates. You never known what you’re gonna get.” Forrest, quoting his mother in this line, uses a box of assorted chocolates as the source, comparing it to a target that is nebulous and difficult to understand: life. Connecting the two concepts illuminates a specific insight about the randomness of life.

In logic and reasoning, and occasionally in literature, analogies are a four-part comparison expressed via the formula of A:B::C:D, or A is to B as C is to D. This comparison depends on the relationship between A and B and the relationship between C and D to make its point, so A can never be D, and B can never be C. For instance, in the analogy “Haggis is to Scotland as caviar is to Russia,” haggis (A) is a food associated with Scotland (B), just as caviar (C) is a food associated with Russia (D). It explains that haggis originated in Scotland by equating its relationship to the relationship between caviar and Russia, as the former originated in the latter.

Relationships that Analogies Can Convey

There are several different comparative concepts that can fit into the A:B::C:D formula.

• Opposite relationships, or antonyms: “cold is to hot as night is to day”
• Similar relationships, or synonyms: “draw is to sketch as sofa is to couch”
• Cause and effect relationships: “smiles are to joy as tears are to grief”
• Part-to-whole relationships: “finger is to hand as leaf is to tree”
• Location relationships: “apples are to orchards as fish are to sea”
• Object-to-action relationships, wherein objects are paired with associated actions: “bake is to pie as simmer is to soup”
• Performer-to-action relationships: “actor is to acting as writer is to writing”
• Performer-to-object relationships: “plumber is to wrench as artist is to paintbrush”
• Function relationships: “pencil is to writing as knife is to cutting”
• Attribute or characteristic relationships: “teachers emit wisdom as lamps emit light”
• Classification relationships: “ waltz is to dance as American Beauty is to rose”

The Function of Analogies

An analogy helps make an abstract concept more tangible and relatable. Many professionals rely on sharing information, and analogies play an important role in making that information understandable. Writers, teachers, advertising and marketing professionals, government officials, scientists, and healthcare providers are just a few of the occupations that involve disseminating information to the general public. Employing analogies is a common method of ensuring an audience understands what they hear.

Analogies also inject substance and emotion into an idea or image. Writers mainly utilize this function to convey meaning and beauty in the stories they tell. It’s nearly impossible to read a novel or a  poem  without finding at least one analogy.

Finally, analogies make compelling arguments in rhetoric. Advertising and marketing lingo, political debates, and  didactic  nonfiction works are some of the arenas where analogies present powerful, persuasive arguments. In 2009, President Barack Obama responded to the Republican criticism of his proposals with a potent analogy comparing politicians’ responsibilities with mopping up messes. “I’m busy. Nancy’s busy with our mops cleaning up somebody else’s mess,” he said. “We don’t want somebody sitting back saying ‘You’re not holding the mop the right way.’ Why don’t you grab a mop? Why don’t you help clean up? ‘You’re not mopping fast enough! That’s a socialist mop!’ Grab a mop. Let’s get to work.”

Analogies, Similes, and Metaphors

While these terms all involve making comparisons, they differ in that analogies merely point out commonalities between two unrelated things, while  similes  and  metaphors  are  figures of speech  that imply the unrelated things are equals. Both similes and metaphors are popular in the target/source approach to analogies.

The difference between similes and analogies is subtle. A simile compares two things through the words  like  or  as . While it can have a powerful effect when making comparisons, analogies address more detailed explanations that elevate the relationship between the compared concepts. The earlier  Forrest Gump  quote is an example of both a simile and an analogy. The first part of the movie line—“Life is like a box of chocolates”—is a simile. The subsequent explanation—“You never know what you’re gonna get”—expands upon the simile’s concept to make a larger point; thus, it is an analogy.

Metaphors and analogies have a similar relationship. Metaphors compare two objects directly, without the linking words that similes use. For example, here is a famous excerpt from the  William Shakespeare  classic  Romeo and Juliet , spoken by Juliet:

What’s in a name? That which we call a rose

By any other word would smell as sweet.

So Romeo would, were he not Romeo call’d,

Retain that dear perfection which he owes

Without that title.

In this passage, Juliet compares Romeo’s perceived perfection to a rose’s sweet scent; since she does not use linking words to state this similarity, her description is a metaphor. It becomes an analogy because she expounds upon it. She starts by declaring that names are irrelevant. To prove this point, she posits that a rose will always smell like a rose no matter what one might call it. Bringing the analogy to a close, she says that, just like the rose, Romeo will remain who he is—someone she loves—no matter what name he has.

Examples of Analogies in Literature

1. William Shakespeare,   As You Like It

Shakespeare’s comedy involves a woman named Rosalind escaping persecution at her uncle’s court and fleeing to the Forest of Arden. There, she finds a cast of quirky characters, including an introspective traveler named Jacques. He delivers one of Shakespeare’s most memorable monologues:

All the world’s a stage,

And all the men and women merely players;

They have their exits and their entrances,

And one man in his time plays many parts,

His acts being seven ages. At first, the infant,

Mewling and puking in the nurse’s arms.

Then the whining schoolboy, with his satchel

And shining morning face, creeping like snail

Unwillingly to school. And then the lover,

Sighing like furnace, with a woeful ballad

Made to his mistress’ eyebrow. Then a soldier,

Full of strange oaths and bearded like the pard,

Jealous in honor, sudden and quick in quarrel…

In this passage, Jacques likens the world to a stage and all the world’s inhabitants to actors performing on the stage. By saying “one man in his time plays many parts,” Jacques—and Shakespeare through him—implies that the roles people fulfill evolve throughout the natural span of human life. Even further, he compares this evolution to the “acts” that make up a play.

2. T.S. Eliot, “The Love Song of J. Alfred Prufrock”

Eliot’s  narrative poem  encompasses a series of thoughts by a narrator on the search for love in a loveless world. Despite the title, it is less a love song and more of a collection of fragmented ideas about frustrated and unexpressed love and devotion.

Let us go then, you and I,

When the evening is spread out against the sky

Like a patient etherized upon a table;

Let us go, through certain half-deserted streets,

The muttering retreats

Of restless nights in one-night cheap hotels

And sawdust restaurants with oyster-shells:

Streets that follow like a tedious argument

Of insidious intent

To lead you to an overwhelming question …

Oh, do not ask, “What is it?”

Let us go and make our visit.

This excerpt depends on vivid analogies. The narrator paints a scene of emptiness and despair by comparing a night to an unconscious patient on an operating table—something that is inert and seemingly lifeless. He also equates the meandering streets to monotonous and devious disputes—both taking travelers places they may not want to go. The result is a bleak snapshot of a city at night and the hopeless man at the center of it.

3. Milan Kundera,   The Unbearable Lightness of Being

Kundera’s novel follows the overlapping stories of Tomáš, Tereza, Sabina, and Franz during the 1968 Prague Spring in Czechoslovakia. Kundera presents many analogies throughout the course of the story. The following passages discuss the depth of Tomáš’s sudden, shockingly intense feelings for Tereza:

He kept recalling her lying on his bed; she reminded him of no one in his former life. She was neither mistress nor wife. She was a child whom he had taken from a bulrush basket that had been daubed with pitch and sent to the riverbank of his bed. She fell asleep. He knelt down next to her….

He had come to feel an inexplicable love for this all but complete stranger; she seemed a child to him, a child someone had put in a bulrush basket daubed with pitch and sent downstream for Tomáš to fetch at the riverbank of his bed.

Kundera underscores Tereza’s innocence and her need to be cared for by comparing her to a helpless child in “a bulrush basket that had been daubed with pitch and sent to the riverbank of his bed.” This analogy employs a metaphor to equate Tereza to the Biblical Moses, who, as a baby, was saved from a basket floating down a river.

Further Resources on Analogies

John F. Sowa and Arun K. Majumdar delve into the details of  using analogies in logical reasoning .

Butte College offers some guidance on  how to write an analogy .

iWriteEssays shares tips on  writing an analogy in essay form .

Copyblogger talks about  the power of analogies in business and marketing .

An academic paper by Yan Chang explores  rhetorical functions and structural patterns of analogies .

Related Terms

How to Write an Analogy Essay

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Article structure

Writing Your Analogy Essay

What are the main features of analogy essay, how to start writing, how to develop an outline, how to write a thesis statement for an analogy essay, how to write an introduction.

• How to write the body paragraphs: Tips on body writing

Additional tips on body writing

How to finish an analogy essay.

• Analogy essay sample

Perhaps you find it difficult to show how two ideas are parallel. However, here is the best method. Use analogy essay to compare the two unlike ideas to demonstrate a common element for both.

The main feature an analogy essay is that it does not have a logical prove anything. Instead, it uses creative skills in writing with no factual arguments. Secondly, the article has an informal or humorous technique of explaining an idea. Therefore, it does not use comparisons and contrasts or cause and effect methods of analysis. On a spate note, the paper is simple and does not use a vocabulary to explain other aspect or ideas. Elsewhere, analogy essay has two parts that include the explainer on one side and the explained on the other hand.

When starting an analogy essay, writers should come up with an analogy. The first part should be the explanation subject while the other half should be the explainer. Secondly, the student should draw a vertical line in the middle of the blank paper and note the characteristics of the explainer. Consequently, the student should elaborate on the explained then match the components. Afterwards, the author should discuss the explainer in one paragraph and then write another paragraph elaborating on the explained. The student should then discuss their differences and review the word choices, especially for denotation and connotation.

The general analogy essay has a title, an introduction, differences, resemblance and a conclusion. The title identifies two subjects, their relationships especially analogous and resemble as well as the analogy of the student. The title usually takes the format of a simile. For example, “Drug Addiction Is like a Life in Jail.”

The second part is the introduction. Here, the student brings the first subject especially the issue in question, its status and recent events on the issue. The student then ends the introduction with an analogy statement. For example, drug addiction is like life in jail due to its impacts on family, friends and the community.

Part three of analogy essay is the differences where a student elaborates minor differences by noting the comparison to the resemblances. The student then elaborates on the significant differences to build the ethos after that forties the rhetorical vulnerability.

The fourth part is the resemblance between the explainer, and the explained to illustrate the argument . The student describes the similarity on separate paragraphs in emphatic order with the most informative resemblance coming at the last paragraph. While writing this section, the student should use transitions to the thesis such as A is like B in terms of…, use transition to the differences such as despite the importance of resemblance.

Lastly, the writer should use a transition from the differences to the resemblance such as more critical, noteworthy, significant, considerable. The last part is the conclusion that repeats the analogy statement, resemblance and provides the next cause of action.

The thesis statement of analogy essay is the analogy statement. The statement should contain the subject of the essay, the purpose and the focus and subdivision of the topic in a transparent way. Thus, informs the reader on the comparison of the explainer in the form of resemblance to the explained regarding different reasons. For example, drug addiction is like life in jail due to its impacts on family, friends and the community.

The introduction brings out the first subject or issue and its status in resemblance to the second subject. Thus, the student should focus on a comparison that hooks the reader to the topic. Afterward, the student gives a brief statement follows the introductory sentence through the elaboration of a recent event, the issue at hand and the analog statement.

How to write body paragraphs: Tips on body writing

• The body paragraphs commence with the differences.
• Provide a proper explanation of the minor differences using comparisons to the resemblances.
• The writer explains the minor differences through the elaboration of the similarities to the resemblances in different paragraphs.
• The student identifies the major differences.
• Commence with the least informative resemblance to the most informative one in different paragraphs.
• Use both resemblance and differences transitions to link the paragraphs.
• Give a summary
• Repeat the analogy statement
• Repeat the resemblances
• Answer the ‘So What?’ question
• Read your written essay aloud and note the errors
• Use Grammarly software to correct spelling, wrongly constructed sentences, and plagiarism
• Give a friend the essay to read to identify the error and correct them before submission.

Analogy essay sample: Responding To Bad News

I have been to online sites since I was in my teenage years. I have received all sorts of news from entertainment, puzzle games, heartbreaking news, and bad and fake news. I have noted that bad news brings shock. But making such claims, shifting the incidence of trauma to bad news is like a smoker blaming the behavior of another person.

While both the actions are similar, they portray differences. In some incidences, smoking may not be the problem of a smoker. Thus, pens when an addict begins smoking from the second-hand cigarette smoke. The addict had no choice since he lives in the environment where there are many cigarette smokers hence it is a deplorable state that happens in most cases. Besides, cigarettes smoking is blamed on other people. In most cases, addicts blame their friends who lure them to the drugs due to peer pressure. However, the shock due to bad news comes as a result of personal behavior and love for the internet. Elsewhere, smoking involves the use of harmful substances that can be legal or illegal. Contrarily, fake news is usually legal but are everywhere on the website hence people get access to them irrespective of the age of the viewer and the place.

Despite the glaring minor differences, the two activities are similar. Both cases lead to shock hence the blames are shifted for the scapegoat of any kind. When such bring negative impacts such as shock, we should not blame others. Instead, we should blame ourselves. Thus, it is a show of irresponsibility when we shift the blame to other people or objects. No one glued your face to watch the bad news hence you got the shock. The person who posted the bad news on the internet never invited you to watch it and see the horrible images or get sad information.

Fake news and smoking have psychological impacts. In most cases, cigarette smokers get depression and dependent on the need for nicotine to make them cool. People who get shocked often get depression due to tormenting images in mind or information whenever they recall. Thus, people who love watching the fake news are prone to disturbing images or sad information. However, a thorough examination reveals that these people even get shocked when they receive fraudulent or sad information from the friends or parents. Therefore, watching the false news on the internet alone does not guarantee that the person will be shocked. Many people are addicted to the internet but do not get shocked hence there are some underlying psychological problems.

In conclusion, it is absurd to blame bad news or fake news for a shock. Besides, smokers choose to smoke cigarette and marijuana among other and get shocked while there are other causes of collapse. Therefore, I fail to understand the reason why shock is blamed on bad news. I watch the sad and fake news but I never been shocked. Thus, the present analogy can help people scrutinize the issue of shock and identify the psychological behavior underlying it rather than shift blame to the sad and fake news.

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• Knowledge Base
• How to write an essay introduction | 4 steps & examples

How to Write an Essay Introduction | 4 Steps & Examples

Published on February 4, 2019 by Shona McCombes . Revised on July 23, 2023.

A good introduction paragraph is an essential part of any academic essay . It sets up your argument and tells the reader what to expect.

The main goals of an introduction are to:

• Catch your reader’s attention.
• Give background on your topic.
• Present your thesis statement —the central point of your essay.

This introduction example is taken from our interactive essay example on the history of Braille.

The invention of Braille was a major turning point in the history of disability. The writing system of raised dots used by visually impaired people was developed by Louis Braille in nineteenth-century France. In a society that did not value disabled people in general, blindness was particularly stigmatized, and lack of access to reading and writing was a significant barrier to social participation. The idea of tactile reading was not entirely new, but existing methods based on sighted systems were difficult to learn and use. As the first writing system designed for blind people’s needs, Braille was a groundbreaking new accessibility tool. It not only provided practical benefits, but also helped change the cultural status of blindness. This essay begins by discussing the situation of blind people in nineteenth-century Europe. It then describes the invention of Braille and the gradual process of its acceptance within blind education. Subsequently, it explores the wide-ranging effects of this invention on blind people’s social and cultural lives.

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Table of contents

Step 1: hook your reader, step 2: give background information, step 3: present your thesis statement, step 4: map your essay’s structure, step 5: check and revise, more examples of essay introductions, other interesting articles, frequently asked questions about the essay introduction.

Your first sentence sets the tone for the whole essay, so spend some time on writing an effective hook.

Avoid long, dense sentences—start with something clear, concise and catchy that will spark your reader’s curiosity.

The hook should lead the reader into your essay, giving a sense of the topic you’re writing about and why it’s interesting. Avoid overly broad claims or plain statements of fact.

Examples: Writing a good hook

Take a look at these examples of weak hooks and learn how to improve them.

• Braille was an extremely important invention.
• The invention of Braille was a major turning point in the history of disability.

The first sentence is a dry fact; the second sentence is more interesting, making a bold claim about exactly  why the topic is important.

• The internet is defined as “a global computer network providing a variety of information and communication facilities.”
• The spread of the internet has had a world-changing effect, not least on the world of education.

Avoid using a dictionary definition as your hook, especially if it’s an obvious term that everyone knows. The improved example here is still broad, but it gives us a much clearer sense of what the essay will be about.

• Mary Shelley’s  Frankenstein is a famous book from the nineteenth century.
• Mary Shelley’s Frankenstein is often read as a crude cautionary tale about the dangers of scientific advancement.

Instead of just stating a fact that the reader already knows, the improved hook here tells us about the mainstream interpretation of the book, implying that this essay will offer a different interpretation.

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Next, give your reader the context they need to understand your topic and argument. Depending on the subject of your essay, this might include:

• Historical, geographical, or social context
• An outline of the debate you’re addressing
• A summary of relevant theories or research about the topic
• Definitions of key terms

The information here should be broad but clearly focused and relevant to your argument. Don’t give too much detail—you can mention points that you will return to later, but save your evidence and interpretation for the main body of the essay.

How much space you need for background depends on your topic and the scope of your essay. In our Braille example, we take a few sentences to introduce the topic and sketch the social context that the essay will address:

Now it’s time to narrow your focus and show exactly what you want to say about the topic. This is your thesis statement —a sentence or two that sums up your overall argument.

This is the most important part of your introduction. A  good thesis isn’t just a statement of fact, but a claim that requires evidence and explanation.

The goal is to clearly convey your own position in a debate or your central point about a topic.

Particularly in longer essays, it’s helpful to end the introduction by signposting what will be covered in each part. Keep it concise and give your reader a clear sense of the direction your argument will take.

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As you research and write, your argument might change focus or direction as you learn more.

For this reason, it’s often a good idea to wait until later in the writing process before you write the introduction paragraph—it can even be the very last thing you write.

When you’ve finished writing the essay body and conclusion , you should return to the introduction and check that it matches the content of the essay.

It’s especially important to make sure your thesis statement accurately represents what you do in the essay. If your argument has gone in a different direction than planned, tweak your thesis statement to match what you actually say.

To polish your writing, you can use something like a paraphrasing tool .

You can use the checklist below to make sure your introduction does everything it’s supposed to.

Checklist: Essay introduction

My first sentence is engaging and relevant.

I have introduced the topic with necessary background information.

I have defined any important terms.

My thesis statement clearly presents my main point or argument.

Everything in the introduction is relevant to the main body of the essay.

You have a strong introduction - now make sure the rest of your essay is just as good.

• Argumentative
• Literary analysis

This introduction to an argumentative essay sets up the debate about the internet and education, and then clearly states the position the essay will argue for.

The spread of the internet has had a world-changing effect, not least on the world of education. The use of the internet in academic contexts is on the rise, and its role in learning is hotly debated. For many teachers who did not grow up with this technology, its effects seem alarming and potentially harmful. This concern, while understandable, is misguided. The negatives of internet use are outweighed by its critical benefits for students and educators—as a uniquely comprehensive and accessible information source; a means of exposure to and engagement with different perspectives; and a highly flexible learning environment.

This introduction to a short expository essay leads into the topic (the invention of the printing press) and states the main point the essay will explain (the effect of this invention on European society).

In many ways, the invention of the printing press marked the end of the Middle Ages. The medieval period in Europe is often remembered as a time of intellectual and political stagnation. Prior to the Renaissance, the average person had very limited access to books and was unlikely to be literate. The invention of the printing press in the 15th century allowed for much less restricted circulation of information in Europe, paving the way for the Reformation.

This introduction to a literary analysis essay , about Mary Shelley’s Frankenstein , starts by describing a simplistic popular view of the story, and then states how the author will give a more complex analysis of the text’s literary devices.

Mary Shelley’s Frankenstein is often read as a crude cautionary tale. Arguably the first science fiction novel, its plot can be read as a warning about the dangers of scientific advancement unrestrained by ethical considerations. In this reading, and in popular culture representations of the character as a “mad scientist”, Victor Frankenstein represents the callous, arrogant ambition of modern science. However, far from providing a stable image of the character, Shelley uses shifting narrative perspectives to gradually transform our impression of Frankenstein, portraying him in an increasingly negative light as the novel goes on. While he initially appears to be a naive but sympathetic idealist, after the creature’s narrative Frankenstein begins to resemble—even in his own telling—the thoughtlessly cruel figure the creature represents him as.

If you want to know more about AI tools , college essays , or fallacies make sure to check out some of our other articles with explanations and examples or go directly to our tools!

• Ad hominem fallacy
• Post hoc fallacy
• Appeal to authority fallacy
• False cause fallacy
• Sunk cost fallacy

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Your essay introduction should include three main things, in this order:

• An opening hook to catch the reader’s attention.
• Relevant background information that the reader needs to know.
• A thesis statement that presents your main point or argument.

The length of each part depends on the length and complexity of your essay .

The “hook” is the first sentence of your essay introduction . It should lead the reader into your essay, giving a sense of why it’s interesting.

To write a good hook, avoid overly broad statements or long, dense sentences. Try to start with something clear, concise and catchy that will spark your reader’s curiosity.

A thesis statement is a sentence that sums up the central point of your paper or essay . Everything else you write should relate to this key idea.

The thesis statement is essential in any academic essay or research paper for two main reasons:

• It gives your writing direction and focus.
• It gives the reader a concise summary of your main point.

Without a clear thesis statement, an essay can end up rambling and unfocused, leaving your reader unsure of exactly what you want to say.

The structure of an essay is divided into an introduction that presents your topic and thesis statement , a body containing your in-depth analysis and arguments, and a conclusion wrapping up your ideas.

The structure of the body is flexible, but you should always spend some time thinking about how you can organize your essay to best serve your ideas.

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How To Write An Analogy Essay

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• Author Sandra W.

What Is An Analogy Essay?

An analogy compares two unlike things to illustrate common elements of both. An analogy essay is an extended analogy, which explains one thing in considerable depth by comparing it to another. Analogy essays discuss nearly anything, as long as the writer can find a comparison that fits.

Click Here To Download Analogy Essay Samples

How to use analogies:

• As introductions for papers where you want to show how two ideas are parallel.
• To explain unknown/abstract concepts in terms familiar to or easily understood by your reader. For example when explaining the storage pattern for a Macintosh computer, you might liken the hard drive icon to a large filing cabinet.

Steps For Writing An Analogy Essay

1. Come up with an analogy

 One-half of the analogy is the subject of explanation, while the other half is the explainer. For example, if you said growing up is like learning to ride a bike, you would be explaining something complex and subtle (growing up) in terms of something simple that your audience will be familiar with (riding a bike.)

2. Draw a vertical line down the middle of a piece of paper to divide it in half .

 On one half, write characteristics of the explainer, and on the other half, the explained. Try to match up the characteristics. For example, training wheels might be similar to having to have lots of supervision when you are young.

3. Write a paragraph discussing the explainer .

 Start with a statement like "Growing up is like learning to ride a bike." Then explain the stages of learning to ride a bike.

4. Write a paragraph discussing the explained .

Start with a statement that gives an overview of what the two shares. In the example above, you might say something like "Growing up also involves getting greater and greater freedoms as you become more confident”. Then explain the steps of the explained in a way that parallels the explainer.

5. Discuss the differences .

Sometimes there is a very important aspect of the explained that does not match up with the explainer. For example, in the above essay, you eventually completely learn to ride a bike, but you never stop growing up and learning new things. You may want to draw attention to this important distinction.

6. Review your choice of words for denotation and connotation .

The allure of analogies is such that they can lend themselves to exaggeration. Fight this tendency, as it will only jeopardize your credibility.

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“He’s as strong as an ox” and “Navigating her emotions is like walking through a maze” are examples of analogies, a common method of comparison in the English language. Analogies are not only prevalent in literature and writing but also in everyday speech, serving as an effective tool for communication. They involve comparing two different things or ideas, which helps clarify or emphasize a point. This literary term, known as an analogy, encompasses various types of comparisons, making it a key element in both formal and informal expression.

Like any other literary analysis sample device, Analogy is used in enhancing the meaning of a composition and is also used in helping the readers in creating a visual image in their minds as well as relationships goals and connections when they would read something difficult or sensitive by comparing one thing to the other. Analogies are often used in thesis , essay writing , report writing , and even in speeches .

What is an Analogy? – Definition An analogy is a comparison between two different things, intended to highlight some form of similarity. It’s a linguistic technique used to explain a new or complex idea by relating it to something familiar. Analogies are often used in teaching, writing, and speaking to make concepts easier to understand. They draw parallels that help people visualize and grasp the essence of the subjects being compared, thereby enhancing comprehension and retention.

Examples of Word Analogies

Analogies are crucial in language and thinking, comparing different concepts to enhance understanding. They are used in education to simplify complex ideas, in standardized tests to assess reasoning skills, and in job interviews to evaluate problem-solving abilities. Additionally, analogies enrich literature and daily communication. Examples like comparing pens to brushes or the sun to planets demonstrate how analogies illuminate various subjects, making them more accessible and relatable.

• Relationship in First Pair : A pen is a tool used for writing.
• Application to Second Pair : Similarly, a brush is a tool, but it is used for painting.
• The analogy connects the function of each tool with its primary action.
• Relationship in First Pair : The sun is a central part of our solar system.
• Application to Second Pair : In a broader scope, a planet is part of a galaxy, which is a larger system of celestial bodies.
• This analogy scales from a smaller celestial relationship (sun and solar system) to a larger one (planet and galaxy).
• Relationship in First Pair : A teacher is the guiding authority in a classroom.
• Application to Second Pair : Similarly, a captain is the guiding authority on a ship.
• The analogy compares the roles of authority and guidance in different settings.
• Relationship in First Pair : A clock is an instrument used to measure and indicate time.
• Application to Second Pair : In a similar vein, a thermometer is an instrument used to measure and indicate temperature.
• This analogy connects the function of measuring and indicating specific elements (time and temperature) with their respective instruments.
• Relationship in First Pair : A book is an individual item that is part of a collection in a library.
• Application to Second Pair : Similarly, a piece of art is an individual item that forms part of a collection in a gallery.
• The analogy shows the relationship of individual items (books, art) as components of larger collections (library, gallery).
• Leaf : Tree :: Wave : Ocean It compares the part-to-whole relationship of a leaf to a tree and a wave to an ocean.
• Author : Novel :: Composer : Symphony This analogy highlights the relationship between an author and their creation, a novel, to a composer and their creation, a symphony.
• Doctor : Hospital :: Teacher : School It parallels the role of a doctor in a hospital to that of a teacher in a school.
• Key : Piano :: String : Guitar This analogy compares the function of a key on a piano to a string on a guitar.
• Nurse : Healthcare :: Lawyer : Law Here, the analogy shows the relationship of a nurse to the field of healthcare and a lawyer to the field of law.

More Analogy Examples for You to Solve

• Owl : Night :: Eagle : _______ (Hint: Consider the time of day each bird is most active.)
• Library : Books :: Museum : _______ (Hint: Think about what a museum houses.)
• Novelist : Words :: Painter : _______ (Hint: Focus on the primary medium used by each artist.)
• Teacher : Educate :: Chef : _______ (Hint: What is the primary action a chef performs?)
• Fish : School :: Wolf : _______ (Hint: Consider the term for a group of these animals.)
• Piano : Music :: Telescope : _______ (Hint: What does a telescope help us explore?)
• Rain : Cloud :: Lava : _______ (Hint: Where does lava originate?)
• Heart : Circulate :: Lungs : _______ (Hint: Think about the primary function of lungs.)
• Leaf : Photosynthesis :: Root : _______ (Hint: Consider the main function of roots in a plant.)
• Baker : Bakery :: Librarian : _______ (Hint: Where does a librarian work?)
• Clock : Time :: Scale : _______
• Ocean : Saltwater :: Lake : _______
• Flower : Garden :: Book : _______
• Knife : Cut :: Screwdriver : _______
• Fire : Heat :: Snow : _______
• Poet : Poem :: Musician : _______
• Bird : Nest :: Bee : _______
• Tree : Oxygen :: Sun : _______
• Actor : Stage :: Athlete : _______
• Shoe : Foot :: Glove : _______
• Phone : Call :: Computer : _______
• Rain : Umbrella :: Sun : _______
• Leaf : Green :: Sky : _______
• Baker : Bread :: Winemaker : _______
• Painter : Portrait :: Writer : _______
• Doctor : Patient :: Teacher : _______
• Fisherman : Fish :: Miner : _______
• Keyboard : Type :: Mouse : _______
• Car : Garage :: Airplane : _______
• Map : Location :: Calendar : _______

Examples of Analogies for Critical Thinking

• Just as a garden is a space where flowers grow and flourish, the mind is a space where ideas are cultivated and developed. This analogy emphasizes the nurturing and growth aspects in both scenarios.
• A book opens the door to knowledge, much like a key unlocks a door. This analogy highlights the unlocking and revealing nature of a book, providing access to new information and understanding.
• A telescope enables us to see distant stars, while a microscope allows us to view tiny bacteria. This analogy draws a parallel between the tools we use to explore vastly different scales of our universe, from the vast to the microscopic.
• Just as a foundation provides stability and support for a building, roots offer support and nourishment to a tree. This analogy compares the underlying support structures in architecture and nature.
• In poetry, words are woven together to create emotional and intellectual art, just as colors are blended in a painting to create a visual masterpiece. This analogy compares the elements of creation in different forms of art.
• A chef uses a recipe to create a dish, just like a composer uses a musical score to create a symphony.
• An author crafts stories with a pen as a sculptor shapes sculptures with a chisel.
• Fire is a source of warmth, as ice is a source of coolness.
• A clock measures time like a thermometer measures temperature.
• Trees produce oxygen, and clouds produce rain.

More Examples for you to Solve:

• Helmet : Head :: Gloves : _______ (Hint: Consider what gloves protect.)
• Sponge : Absorb :: Sieve : _______ (Hint: Think about what a sieve does with liquids.)
• Caterpillar : Butterfly :: Tadpole : _______ (Hint: Consider the lifecycle transformation.)
• Magnet : Attract :: Repellent : _______ (Hint: Think of the opposite action of attracting.)
• Flashlight : Darkness :: Air Conditioner : _______ (Hint: What does an air conditioner alleviate?)
• Furnace : Heat :: Refrigerator : _______ (Hint: Think about what a refrigerator preserves.)
• Anchor : Ship :: Brakes : _______ (Hint: Consider what brakes do to a vehicle.)
• Recipe : Dish :: Blueprint : _______ (Hint: What is created using a blueprint?)
• Vaccine : Disease :: Fertilizer : _______ (Hint: Think about what fertilizer promotes.)
• Lighthouse : Ships :: Traffic Light : _______ (Hint: Consider what traffic lights guide.)
• Archive : Documents :: Museum : _______
• Rudder : Direction :: Engine : _______
• Thermometer : Temperature :: Barometer : _______
• Author : Story :: Composer : _______
• Nest : Bird :: Den : _______
• Broom : Sweep :: Hose : _______
• Window : Light :: Dam : _______
• Dew : Morning :: Frost : _______
• Key : Lock :: Code : _______
• Easel : Painter :: Anvil : _______

Analogy Examples in Sentence

• Life is like a box of chocolates; you never know what you’re going to get. This analogy compares the unpredictability of life with the surprise of picking a chocolate from an assorted box.
• The heart of a car is its engine. This draws a parallel between the essential role of the heart in the human body and the engine in a vehicle.
• A good book is a magic gateway into another world. Here, the transformative power of reading is likened to a portal leading to new, undiscovered realms.
• The classroom was a zoo. This analogy suggests the noisy and chaotic nature of the classroom, similar to the lively environment of a zoo.
• Her eyes were windows to her soul. This sentence compares eyes to windows, implying that they reveal deep emotions or the essence of a person.
• Time is a thief. This analogy implies that time steals moments from our lives, much like a thief takes away possessions.
• The computer in the modern age is like a pen in the past. This draws a comparison between the role of computers today in communication and creation, and the role of the pen in earlier times.
• The moon is a ghostly galleon tossed upon cloudy seas. This vividly portrays the moon as a ghostly ship sailing across the sky, with clouds as its sea.
• The world is a stage, and we are merely players. This famous analogy from Shakespeare suggests that life is like a play, and everyone has a role to perform.
• Watching the show was like walking through a dream. This suggests the surreal, dream-like quality of the show, likened to the experience of walking through a dream.

Examples of Analogy in Literature

Analogy is a common literary device used by authors to draw comparisons between two different things, often to highlight a particular theme or idea. Here are some examples of analogy in literature:

• This famous analogy compares the world to a stage and life to a play, suggesting that our lives are structured like a theatrical performance, with different roles and acts.
• Orwell uses farm animals to represent historical figures and social classes, drawing parallels between the farm’s descent into tyranny and the history of Soviet communism.
• Here, the prejudice and racism in Maycomb are compared to a disease, suggesting they are both harmful and spread uncontrollably.
• The diverging paths symbolize life’s different options and directions, and the choice of path represents a decision that shapes one’s future.
• In this analogy, experiences are likened to physical parts of a person, suggesting that they become integral to one’s identity.

Types of Analogy

• Literal Analogy : Compares two similar things or classes of things that have the same relationship. For example, “Just as a sword is the weapon of a warrior, a pen is the weapon of a writer.”
• Figurative Analogy : Involves a comparison between two things that are different in nature, often used to explain a concept or to persuade. For instance, comparing the mind to a computer.
• Relational Analogy : Focuses on the relationship between pairs of words. For example, “Hand is to glove as foot is to sock.” The relationship is about things that cover.
• Personal Analogy : Requires imagining oneself as an object or a situation. It’s often used in problem-solving to look at things from a different perspective.
• Predictive Analogy : Used to predict the outcome of some actions by comparing it to known outcomes in similar scenarios. For example, “If you overwater a plant, it dies; similarly, too much of anything, even a good thing, can be harmful.”
• Analogical Argument : Used in persuasive writing and speech, where an analogy is used as an argument or as a part of an argument.
• Negative Analogy : Focuses on comparing dissimilarities between two things. For example, “Arguing on the internet is unlike a sports competition; there are no clear winners.”
• Medical Analogy : Common in medical fields, where symptoms or conditions of a patient are compared to typical cases to diagnose or treat.
• Historical Analogy : Draws a comparison between historical events to explain or predict current events. For example, comparing modern political situations to historical ones.
• Mathematical Analogy : Involves comparing mathematical relationships, often used in teaching complex mathematical concepts.

How to Write an Analogy

• Identify the Core Idea or Concept : Begin by determining the main idea or concept you want to explain or enhance through the analogy.
• Find a Relatable Comparison : Choose a familiar or easily understandable object, situation, or concept that shares similarities or relationships with your core idea.
• Establish a Clear Relationship : Ensure that the relationship between the two entities in your analogy is clear and logical. The comparison should highlight the similarities or explain the concept effectively.
• Use Simple and Effective Language : The effectiveness of an analogy often lies in its simplicity. Use language that is easy to understand and avoids complexity.
• Be Consistent : Maintain consistency in the elements of your analogy. Mixing different metaphors or comparisons can lead to confusion.
• Test Your Analogy : Before finalizing, test your analogy to see if it makes the concept clearer and is understandable to your intended audience.

When to Use Analogy

• To Simplify Complex Ideas : Analogies are excellent for breaking down complex or abstract concepts into simpler, more relatable terms.
• In Teaching and Education : They are used to explain new or difficult subjects by relating them to something familiar to the students.
• To Persuade or Argue : In rhetoric and writing, analogies can make arguments more persuasive by drawing parallels that the audience can easily understand.
• To Enhance Writing : Writers often use analogies to add depth, creativity, and imagery to their writing, making it more engaging and vivid.
• In Problem-Solving : Analogies can help in seeing problems from a new perspective, leading to innovative solutions.

How Does Analogy Work

• By Establishing Relationships : Analogies work by drawing a parallel between two disparate entities, emphasizing their similarities in relation to each other.
• Through Familiarity and Understanding : They often use familiar concepts to explain unfamiliar ones, making new or complex information more digestible and easier to grasp.
• Creating Mental Images : Good analogies create vivid mental images, which can be more effective in communication than abstract concepts.
• Enhancing Memory and Retention : Because they often involve storytelling or imagery, analogies can be more memorable than straightforward explanations, aiding in better retention of the information.
• Building on Prior Knowledge : Analogies leverage the audience’s existing knowledge or experience, providing a foundation for understanding new information.

Analogies, when used effectively, can be powerful tools for communication, learning, and creativity, bridging gaps in understanding by connecting the unknown to the

25 Examples of Analogies

1. life is like a race.

2. Finding a Good Man is Like Finding a Needle in a Haystack

3. Just as a Sword is the Weapon of a Warrior, a Pen is the Weapon of a Writer

4. That’s as Useful as Rearranging Deck Chairs on the Titanic.

5. How a Doctor Diagnoses Diseases are Like How a Detective Investigates Crimes

6. Explaining a Joke is Like Dissecting a Frog

7. Just as a Caterpillar Comes out of its Cocoon, So we Must Come out of our Comfort Zone

8. A Movie is a Roller Coaster Ride of Emotions.

9. You are as Annoying as Nails on a Chalkboard.

10. Life is Like a Box of Chocolates – You Never Know What You’re Gonna Get!

11. Reasoning Analogy

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12. Analogy as the Core of Cognition

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13. Analogy by Similarity Example

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14. Semantic Analogy Example

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15. Teaching by Analogy Example

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16. Animal Analogies Example

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17. The Principle of Analogy

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18. Analogy as Exploration

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19. Science Analogy Example

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20. Practice Analogy Questions

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21. The Reaction Against Analogy

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22. Transformational Analogy Example

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23. Curve Analogies Template

24. Analogy and Transfer

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25. Analogy in Thinking Example

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What is an Analogy?

A  figurative analogy is used when you compare two completely different ideas or things and use its similarities to give an explanation of things that are hard to understand or are too sensitive. Analogies are often used in thesis , essay writing , report writing , and even in speeches .

Step 1: Identify the Two or More Things You Want to Compare

To start is to identify two or more words or phrases you may want to compare. This is the first step to writing your analogy. You must also be careful with the analogy you are going to be using, if your audiences are children, you can use analogy for kids . The important thing is to be able to explain the idea or the concept.

Step 2: Do Your Research on the Similarities

In order for you to explain and understand the similarities between the words or phrases that you are using for analogy, you must first do your research about it. Simply writing two words together to compare is not enough. It is also important for you to understand what these two words mean and how similar are they in order for them to be compared.

Step 3: Make the Analogies

Make or create the analogies once you have figured out the similarities of the words you have written. If you have not, go back to the second step and continue until you found them. The analogy must be in a simple sentence or a simple statement. Avoid using technical jargon that defeats the purpose of the analogy.

Step 4: Give the Explanation of the Chosen Analogies

The last step is to give out the explanation of the chosen analogies. The explanation will help give the reader the idea of what they are reading and can grasp the information from the analogies. Provided the fact that these chosen analogies details and examples to back it.

What is the difference with analogy, simile and metaphor?

More often than not, an analogy is sometimes mistaken with the other figures of  speech examples , namely  simile  and  metaphor , because these are used to seek relationships between concepts and things. The  figurative language  simile compares two objects that use comparison words such as ‘like’ and ‘as’ where the whole metaphor would compare two objects with the use of the said comparison words.

What are the elements of an analogy?

What you can expect in the elements of an analogy are as follows: the two or more concepts that need to be compared, the shared characteristics of these concepts, the differences of the concepts, the purpose, the clarification, and lastly the creativity.

What is the difference between analogy and idioms?

An analogy is a comparison of two or more things, topics or concepts that helps explain the topic. An idiom is a phrase that has a figurative language or meaning to it.

Analogy compares two completely different things and look for similarities between two things or concepts and it only focuses on that angle. The use and purpose of analogies may baffle any reader at first but once they would realize how analogies can help writers in making difficult and sensitive topics or things understandable, analogies might be used frequently.

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