In what follows I would like to introduce you to analogy from a Thomistic perspective. I will begin with a look at analogy in general. Then I will discuss some different kinds of analogy. And, lastly, I will offer a few examples of what we can “do” with analogy.
Analogy in general
We can use the same word in different ways so that its meaning in one case will be completely different from its meaning in another case. If I say “The bow of the Titanic plunged beneath the waves” and “We will not bow to their demands,” the word “bow” in the first sentence does not mean at all what it means in the second sentence. We would say that the relationship between the two meanings of “bow” is equivocal, that is, the meanings have no connection whatsoever.
If I say “The volcano is in the middle of the island” and “Every island is surrounded by water,” the word “island” has the very same meaning in each case. We would say that the relationship between the meaning of “island” in the first sentence and its meaning in the second sentence is univocal.
But there is yet a third kind of relationship that the meanings of a word can have in different instances of its use. This third kind of relationship is called analogical and St. Thomas Aquinas notes that it stands midway between equivocity and univocity.1 If I say “This Scotch is good” and “My wife thinks Kristin Lavransdatter is a good book,” the meanings of “good” in these two sentences are partly the same and partly different. In both cases “good” means that the thing in question has met certain expectations (or perhaps that it has achieved a certain perfection with respect to the kind of thing it is). But it should be evident to everyone that what makes a Scotch good will be different from what makes a novel good. Some people prefer Scotch with a peaty taste but no one would say that peatiness is what we should look for in a novel.
So, “good” has an analogous meaning in these sentences. It is not meant in a completely different way in them nor is it meant in exactly the same way.
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