Abstract

In contemporary philosophical circles, there has been recent debate concerning the nature of natural kinds. Natural kinds are the species and genera into which we place individuals and by means of which we identify and individual as being of a kind. On the one hand, it appears that these kinds are merely the products of convention; that the distinctions between cats, dogs, and diamonds are due to pragmatic groupings of individuals in accordance with our scientific models, the structure of our language, thought patterns, sensory make-up, etc. On the other hand, it would seem that the distinction between dogs and diamonds is irrevocably real and embedded in nature itself, that such distinctions are no more arbitrary or contingent upon our sensory make-up than is the distinction between the living and the dead. ;It is my contention that in The Categories, Aristotle addresses many of these problems with an encouraging theory of natural kinds based on his account of predication and inherence, and his concept of contrary opposites. The dissertation breaks down into two parts. In the first part, Chapters One through Four, I critically examine Aristotle's technical notions of 'said of' and 'in' a subject and thereby show that Aristotle draws a distinction between two types of kinds with two corresponding types of individual exemplifications. I argue that with these two types of kinds and individuals, Aristotle provides us with an exhaustive treatment of universals as kinds and all particulars as exemplifications of a kind. ;In the second part, Chapters Five through Six, I demonstrate that because Aristotle's theory of kinds entails his account contrary opposites, his theory constitutes a form of scientific realism. I argue that 'contraries' can only be described as logical disjunctions of mutually exclusive predicates that, as disjunctions, are predicated of kinds and not individuals. I show that the relation of 'contraries' to one another and to the subjects of which they are predicated is synthetic and empirical for Aristotle. I argue that Aristotle's claim that substance is unique and alone in being able to 'receive contraries' constitutes the logical prolegomena for an account of kinds in terms of a nomological principle of identity through change that Aristotle articulates more fully in the Physics