Predicates: A Thomist Analysis

The Thomist 63 (1999): 455-60 PREDICATES: A THOMIST ANALYSIS JOHN PETERSON University ofRhode Island Kingston, Rhode Island APREDICATE is not just another name for a set. Some predicates are species and some are genera. Any species is predicable of an individual that belongs to that species but no set is predicable of an individual member of that set. One can say that Socrates is human but not that Socrates is the set of humans. Further, any genus is predicable of its included species but no set is predicable of any one of its subsets. One can say that humans are animals but not that the set of humans is the set of animals. Beyond saying that some predicates are not sets, we may say that no predicate of any subject is a set. Take any predicate F that is truly said of a subject a. If F is a set then it follows that a is a set. But a is evidently not a set but a member of a set. Otherwise any member of a set is itself a set and the division of set and setmember collapses. Suppose the set of tigers comprises two members, Josh and Jake. IfJosh dies, then it is truly said that the set is reduced by one member, that it goes from having two members to having just one. But this makes sense only if it is the same set that once had a pair of members and now has one. If it is one set that has two members and another that has one then no set is reduced by one member. But a set is reduced by one member and it is evidently not Jake who is so reduced. So the difference of set and set-member remains even in a set of one. But what are predicates if they are not sets? Since it is by definition 'of' or 'about' a subject, a predicate is a relational concept . As a genus is the genus of a species and a species is the species of a genus, so too, a predicate is the predicate of a subject. 455 456 JOHN PETERSON By the same token, a subject is by definition the subject of a predicate. With respect to such relational concepts, one cannot say what they are apart from bringing in their respective correlatives . To try to do so substitutes the abstract for the concrete and confuses relations with things. With this as our cue, we consider two puzzles about predication . The puzzles as well as their solutions we owe to Aquinas.1 The answers to both flesh out the subject-predicate tie. They also illumine what figures in that relation, including the idea of a predicate. Aquinas frames the first puzzle as a dilemma; call it the dilemma of predication. The tiger that is predicated of Jake is either particular or universal. But in either case predication is pre-empted. No particular is predicated of a subject. And if it is the universal tiger that is predicated of Jake, then the particular thing Jake is said to be a universal. IfJake is a tiger and tiger is a universal then the absurdity follows that Jake is a universal.2 Yet we do truly say that Jake is a tiger. How is that possible? Aquinas's solution is that the tiger that is here predicated of Jake is neither particular nor universal.3 Any thing is either particular or universal, but what the predicate tiger signifies is not a thing. It is tiger taken in abstraction from the manner in which it is either in particular things like Jake or in universal things like concepts. By analogy, suppose that Jones is a teacher by day and a salesman by night. By day he teaches American history; by night he sells furniture. Yet it is the same Jones who takes on both modes. Just as we say that the teacher-mode and the salesmanmode are accidental to Jones so are the particular and universal modes accidental to the tiger that is said of Jake. That tiger is something neutral between the two modes just as Jones is something neutral between his...