Thursday, July 31, 2008

Logic I, Lesson 2: Univocal, Equivocal, & Analogical Terms

From Aristotle's Categories 1:

Things are said to be named 'equivocally' when, though they have a common name, the definition corresponding with the name differs for each. Thus, a real man and a figure in a picture can both lay claim to the name 'animal'; yet these are equivocally so named, for, though they have a common name, the definition corresponding with the name differs for each. For should any one define in what sense each is an animal, his definition in the one case will be appropriate to that case only.

On the other hand, things are said to be named 'univocally' which have both the name and the definition answering to the name in common. A man and an ox are both 'animal', and these are univocally so named, inasmuch as not only the name, but also the definition, is the same in both cases: for if a man should state in what sense each is an animal, the statement in the one case would be identical with that in the other.

From Ralph McInerny's Aquinas & Analogy, p. 96:

Things are to be named analogously when, though they have a name in common, the definitions corresponding with the name are partly the same and partly different, with one of those definitions being prior to the others... "For example, 'healthy' as said of urine signifies a sign of the health of the animal, but said of medicine it signifies the cause of the same health" [St. Thomas, Summa Theologiae I.15.5c].


Don Paco said...

Explanation of the pictures:

1) The pig on the front and the pig in the back are given the name "pig" univocally (same name, same meaning).

2) The pen in which the pigs are eating and the pen used for writing are given the name "pen" equivocally (same name, different meaning).

3) The pigs may be said to be "healthy" pigs, and the food they are eating may be said to be "healthy" food. Now, the pigs and the food are both "healthy" analogically, i.e., in different, though related, senses of the word. The pigs are healthy in the strict sense of having proper biological functions, but the food is only healthy in reference to the health of the pigs: the food is healthy in an analogical sense because it causes the health in the pigs. (The food does not have the proper biological functions that warrant the pigs' being called "healthy" in the strict sense.)

Abercrombie @ Christ said...

If one takes the 'pen' and jabs the pig in the back,would that be analagous to a 'pig in a poke'?

Luis Vivanco said...

One can make a lot of analogies of proportion with arithmetics. For example: 8 is to 4, as 4 is to 2, or 240 is to 120 as 120 is to 60. Also with relations like: "John is to Bill, as Bill is to George", Because John is Bill's father and Bill is George's Father.

eness said...

I had a Thomistic professor claim that analogy was not a species of equivocation.