On Determining What There Is: The Identity of Ontological Categories in Aquinas, Scotus, and Lowe (review)

Aristotle had a theory of categories. In its canonical form, it involved a list of ten items: substance, quantity, relation, quality, when, where, action, passion, position, and having. In Aristotle, ‘katēgoria’ is a technical term meaning predication or predicate. This predicative aspect is often missing when we speak of categories today, but it was obvious to Aristotle’s medieval interpreters since katēgoria is rendered in Latin by praedicamentum, from the verb praedicare (to predicate).

Aristotle never justified his list or explained how he arrived at it. Thomas Aquinas famously provided two quite similar attempts at accounting for it (sufficientiae). Symington’s book focuses on the one found in his Metaphysics commentary (nn. 889–94).

Besides an introduction and a brief conclusion, the book contains four chapters. In chapter 1, Symington offers some criticisms of the standard interpretation of Aquinas’s sufficientia advanced by John Wippel and others, and attempts to develop a new interpretation. In chapter 2, he presents what he takes to be John Duns Scotus’s criticisms of Aquinas’s account. In chapter 3, he tries to defend Aquinas’s position as he understands it against these criticisms. In chapter 4, he jumps to the present day and the four-category ontology of Jonathan Lowe, and (somewhat surprisingly) argues that the method of identifying categories he attributes to Aquinas can also be used to identify precisely the four categories Lowe identifies, and that it is, in fact, superior to Lowe’s own method of identifying them. So while the book’s subtitle lists all three philosophers on an apparently equal footing, Aquinas is quite clearly its focus and philosophical hero.

Much here hangs on the interpretation presented in chapter one. Aquinas’s sufficientia occurs during his exposition of Metaphysics V.7, where Aristotle claims that “all those are said to be in their own right [secundum se] which signify the figures of predication” (1017a22–23). Aquinas first explains that since being is not a genus, and therefore cannot be divided into species by divisive differentiae, “it is necessary that being is contracted into the different genera in accordance with the different modes of predicating, which follow upon different modes of being” (889–90). “And,” he adds, “the items into which being is first divided are called categories [praedicamenta], precisely because they are distinguished according to the different modes of predicating [praedicandi]” (890). Symington’s interpretation basically consists in the claim that Aquinas is here referring to the modes of per se predication that Aristotle mentions in Posterior Analytics I.4 (a work Aquinas also commented on), and in showing or suggesting how these three (by Aquinas’s count) modes might yield the ten categories (in effect, Symington somewhat unsatisfactorily limits himself to the first four).

I must admit that I find the proposed interpretation implausible. It is quite clear that the Posterior Analytics modes are not what Aristotle means by figures of predication in Metaphysics V.7, and nothing in Aquinas’s comments suggests that he thought so. Here is what Thomas says: “Thus, since of items predicated some signify what [quid], i.e., substance, some of-what-quality [quale], some of-what-quantity [quantum], and so on, it is necessary that ‘to be’ signifies the same as each mode of predicating. For example, when one says ‘a man is an animal,’ ‘to be’ signifies substance; when one says ‘a man is white,’ it signifies quality; and so on” (890). Basically, one mode or figure of predicating is quidditative (the predicate expresses what the subject is), another mode is qualitative (the predicate expresses of what quality the subject is), a third mode is quantitative (the predicate expresses of what quantity the subject is), and so on. In the first mode the predicate signifies substance, in the second mode the predicate signifies quality, in the third mode the predicate signifies...