Comparing one situation to another to try and make it clearer to others. It is very easy to make a bad analogy, especially when you try and compare two situations too much.

Analogy is the comparison of one thing to another. Language generally has two major kinds, metaphor and simile.

The Analogy
*Adapted from a third year ethics lecture by Dr. Mano Daniel*

An analogy is a comparison showing resemblance between two or more entities; calling attention to these likenesses is to draw an analogy.
Analogies help people to relate known things to unknown things. They are also argumentative tools used in debate that are useful in creating perspectives by relating to similar, possibly unrelated things.
There are four kinds of analogies

Non-Argumentative or Illustrative Analogies
The non-argumentative or illustrative analogies attempt to compare one thing to another with intent to explain, not to argue.
Descriptive Analogies
The descriptive analogies is often used to create a lively description.
Ants never make their way to an empty granary: no friends will visit departed wealth
This analogy allows the reader to form a picture, it does not establish or prove a conclusion.

Explanatory Analogies
This analogy creates understanding between something unknown by relating it to something known. It provides insight by edifying, understanding by relating what you don’t know with what you do know. Not to persuade, but to understand.

Argumentative Analogies
Argumentative analogies help us to form an inference by making a comparison between things that are familiar to us and things that are not so familiar.
Deductive Analogies
Treating like cases alike; being consistent with our comparisons. Irrelevant reasons should be kept out. Often deductive analogies use hypothetical or made-up comparisons in order to make a point. The idea then is whether or not the “unknown” and the “known” are actually similar.
Ex: “We would think it wrong for creatures from outer space, vastly more intelligent than humans, to inflict pain on us in raising humans for their meat counters. So analogously, it is wrong for us to inflict pain on animals, just because we are more intelligent than they are” (M. Daniel).
For this analogy, you would have to consider: is an alien from outer space similar to us? (Treat like-as-like). If we disagree that aliens and humans are similar than this analogy is not effective.

Inductive Analogies
These analogies are more for basis of predictions rather than decisions/persuasion. This type of analogy draws comparison between cases and suggests that since the analogy hold some respects, it is likely to hold in other respects as well.
Ex: A certain type of medication was tested on a rat. The rat developed a serious side effect and therefore a human being would.
This is a prediction based on the fact that human beings and rats have certain similarities that may cause us to react similarly.
Ex: A certain type of medication was tested on a house fly. The house fly died, therefore a human being would die.
This analogy is not a good one. We are more similar to rats than to house flies. Rats and human beings are both mammals, whereas a housefly is an insect. In deductive analogies the “known” and the “unknown” must both be real things, neither are allowed to be hypothetical.

In biology, this refers to two anatomical structures or behavioral traits within different and unrelated organisms which perform the same functions in each organism but which did not originate from an ancestral structure or trait that the organisms' ancestors had in common. Instead, the structures or traits arose separately and then later evolved to perform the same function (or similar functions). See also convergent evolution. Compare homology.

From the BioTech Dictionary at For further information see the BioTech homenode.

A*nal"o*gy (#), n.; pl. Analogies (#). [L. analogia, Gr. , fr. : cf. F. analogie. See Analogous.]


A resemblance of relations; an agreement or likeness between things in some circumstances or effects, when the things are otherwise entirely different. Thus, learning enlightens the mind, because it is to the mind what light is to the eye, enabling it to discover things before hidden.

Followed by between, to, or with; as, there is an analogy between these objects, or one thing has an analogy to or with another.

Analogy is very commonly used to denote similarity or essential resemblance; but its specific meaning is a similarity of relations, and in this consists the difference between the argument from example and that from analogy. In the former, we argue from the mere similarity of two things; in the latter, from the similarity of their relations.


2. Biol.

A relation or correspondence in function, between organs or parts which are decidedly different.

3. Geom.

Proportion; equality of ratios.

4. Gram.

Conformity of words to the genius, structure, or general rules of a language; similarity of origin, inflection, or principle of pronunciation, and the like, as opposed to anomaly.



© Webster 1913.

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