What Is an Analogy?

Questions and Answers About Rhetorical Strategies

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An analogy is a type of composition (or, more commonly, a part of an essay or speech) in which one idea, process, or thing is explained by comparing it to something else.

Extended analogies are commonly used to make a complex process or idea easier to understand. "One good analogy," said American attorney Dudley Field Malone, "is worth three hours' discussion."

"Analogies prove nothing, that is true," wrote Sigmund Freud, "but they can make one feel more at home." In this article, we examine the characteristics of effective analogies and consider the value of using analogies in our writing.

n analogy is "reasoning or explaining from parallel cases." Put another way, an analogy is a comparison between two different things in order to highlight some point of similarity. As Freud suggested, an analogy won't settle an argument, but a good one may help to clarify the issues.

In the following example of an effective analogy, science writer Claudia Kalb relies on the computer to explain how our brains process memories:

Some basic facts about memory are clear. Your short-term memory is like the RAM on a computer: it records the information in front of you right now. Some of what you experience seems to evaporate--like words that go missing when you turn off your computer without hitting SAVE. But other short-term memories go through a molecular process called consolidation: they're downloaded onto the hard drive. These long-term memories, filled with past loves and losses and fears, stay dormant until you call them up.

("To Pluck a Rooted Sorrow," Newsweek, April 27, 2009)

Does this mean that human memory functions exactly like a computer in all ways? Certainly not. By its nature, an analogy offers a simplified view of an idea or process—an illustration rather than a detailed examination.

Analogy and Metaphor

Despite certain similarities, an analogy is not the same as a metaphor.

As Bradford Stull observes in The Elements of Figurative Language (Longman, 2002), the analogy "is a figure of language that expresses a set of like relationships among two sets of terms. In essence, the analogy does not claim total identification, which is the property of the metaphor. It claims a similarity of relationships."

Analogy and Comparison & Contrast

An analogy is not quite the same as comparison and contrast either, although both are methods of explanation that set things side by side. Writing in The Bedford Reader (Bedford/St. Martin's, 2008), X.J. and Dorothy Kennedy explain the difference:

You might show, in writing a comparison and contrast, how San Francisco is quite unlike Boston in history, climate, and predominant lifestyles, but like it in being a seaport and a city proud of its own (and neighboring) colleges. That isn't the way an analogy works. In an analogy, you yoke together two unlike things (eye and camera, the task of navigating a spacecraft and the task of sinking a putt), and all you care about is their major similarities.

The most effective analogies are usually brief and to the point—developed in just a few sentences. (See Analogies in David Simon's Homicide.) That said, in the hands of a talented writer, an extended analogy can be illuminating.

See, for example, Robert Benchley's comic analogy involving writing and ice skating in "Advice to Writers."

Argument From Analogy

Whether it takes a few sentences or an entire essay to develop an analogy, we should be careful not to push it too far. As we've seen, just because two subjects have one or two points in common doesn't mean that they are the same in other respects as well. When Homer Simpson says to Bart, "Son, a woman is a lot like a refrigerator," we can be fairly certain that a breakdown in logic will follow. And sure enough: "They're about six feet tall, 300 pounds. They make ice, and . . . um . . . Oh, wait a minute. Actually, a woman is more like a beer." This sort of logical fallacy is called the argument from analogy or false analogy.

Examples of Analogies

Judge for yourself the effectiveness of each of these three analogies.

Pupils are more like oysters than sausages. The job of teaching is not to stuff them and then seal them up, but to help them open and reveal the riches within. There are pearls in each of us, if only we knew how to cultivate them with ardor and persistence.
(Sydney J. Harris, "What True Education Should Do," 1964)

Think of Wikipedia's community of volunteer editors as a family of bunnies left to roam freely over an abundant green prairie. In early, fat times, their numbers grow geometrically. More bunnies consume more resources, though, and at some point, the prairie becomes depleted, and the population crashes.

Instead of prairie grasses, Wikipedia's natural resource is an emotion. "There's the rush of joy that you get the first time you make an edit to Wikipedia, and you realize that 330 million people are seeing it live," says Sue Gardner, Wikimedia Foundation's executive director. In Wikipedia's early days, every new addition to the site had a roughly equal chance of surviving editors' scrutiny. Over time, though, a class system emerged; now revisions made by infrequent contributors are much likelier to be undone by élite Wikipedians. Chi also notes the rise of wiki-lawyering: for your edits to stick, you've got to learn to cite the complex laws of Wikipedia in arguments with other editors. Together, these changes have created a community not very hospitable to newcomers. Chi says, "People begin to wonder, 'Why should I contribute anymore?'"--and suddenly, like rabbits out of food, Wikipedia's population stops growing.
(Farhad Manjoo, "Where Wikipedia Ends." Time, Sep. 28, 2009)

The "great Argentine footballer, Diego Maradona, is not usually associated with the theory of monetary policy," Mervyn King explained to an audience in the City of London two years ago. But the player's performance for Argentina against England in the 1986 World Cup perfectly summarized modern central banking, the Bank of England's sport-loving governor added.

Maradona's infamous "hand of God" goal, which should have been disallowed, reflected old-fashioned central banking, Mr. King said.

It was full of mystique and "he was lucky to get away with it." But the second goal, where Maradona beat five players before scoring, even though he ran in a straight line, was an example of the modern practice. "How can you beat five players by running in a straight line? The answer is that the English defenders reacted to what they expected Maradona to do. . . . Monetary policy works in a similar way. Market interest rates react to what the central bank is expected to do."
(Chris Giles, "Alone Among Governors." Financial Times. Sep. 8-9, 2007)

Finally, keep in mind Mark Nichter's analogical observation: "A good analogy is like a plow which can prepare a population's field of associations for the planting of a new idea" (Anthropology and International Health, 1989).