The extended analogy

"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.

As defined in our glossary, an 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.

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.

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."