The Art of Logic · Part 9 · Propositions · B2–C1
Distribution and the Predicables
Part 9 of The Art of Logic: a term is distributed when a proposition speaks about every member of its class. The rule decides whether a syllogism works. And every predicate is related to its subject in one of five ways. Quantifiers with of (all of, each of, none of, some of, any of), with Philo, Sophia, Marcos and Demetria.
Tonight, the hardest idea in this part of logic: distribution.
Like giving bread to every single person in the room. A term is distributed when the proposition says something about every member of its class.
Then the term is undistributed. Learn this tonight, and the syllogism next week will be easy.
In All sailors are swimmers (A), the subject is distributed: we speak of every sailor. The predicate is not: we do not say anything about every swimmer. In No sailor is a fish (E), both terms are distributed: no sailor is any fish, and no fish is any sailor. In Some sailors are swimmers (I), neither term is distributed. In Some sailors are not swimmers (O), only the predicate is: those sailors are outside the whole class of swimmers.
An easy rule: universal propositions distribute their subjects; negative propositions distribute their predicates.
The predicables are the five ways a predicate can be related to its subject, from Aristotle and his later commentator Porphyry: genus (a human is an animal), species (Socrates is a human), difference (a human is rational), property (a human can laugh, something that belongs to every human and only to humans, but is not the essence), and accident (Socrates is snub-nosed).
Or try our free games and lessons.