Aristotle's Theory of Substance: The Categories and Metaphysics Zeta (review)

Michael Wedin has written the equivalent for Aristotle of what biblical scholars would call a "harmony of the gospels." It is a wonderfully rich and argumentatively dense reconstruction of Aristotle's two most important treatises on substance, the Categories and Metaphysics Zeta, works that many of our most able Aristotle scholars have declared irreconcilable.

The first chapter, on "the plan" of the Categories, includes a sensible account of the role in that work of the "onymies," as Wedin calls homonymy, synonymy, and paronymy. The second chapter, which focuses on "nonsubstantial individuals" in the Categories, gives the most philosophically sophisticated reconstruction known to me of how Aristotle might have conceived this white in Socrates to be a nonrecurrent particular. Having myself contributed to the glut of recent scholarship on nonsubstantial individuals in the Categories, I have personal, as well as professional, reasons to praise the rigor and insight of this chapter.

In Chapter 3 Wedin tries to pin down the ontological commitment of Aristotle's Categories. Since, if there were no primary substances there would not be anything else, the fundamental ontological commitment of the Categories is a commitment to primary substances. Individual nonsubstances exist just in case there are primary substances in which they inhere. As for species and genera of substances and species and genera of the nonsubstantial individuals that inhere in them, Wedin finds Aristotle curiously indifferent to their existence.

Chapter 4, a transitional chapter, takes up a range of possible views on the relation between the Categories and Metaphysics Zeta. Incompatibilism is argued against, yet the arguments for compatibilism in recent commentaries are found to be insufficient. In the next chapter Wedin moves on to his own statement of, and justification for, compatibilism.

The key to Wedin's compatibilist interpretation is the distinction he draws between being a substance and being the "substance-of" something. Zeta can then be seen to be supplementing, rather than revising, let alone contradicting, the Categories, if Zeta can be understood to be about the substance-of the primary substances of the Categories (157-8).

Aristotle proposes in Z3 three candidates for what the substance of, say, Socrates, is, namely, his matter, his form, and the compound of the two. Aristotle settles on form and discusses form as essence in Z4 and Z5, which discussion Wedin takes up in his own Chapter 6. Then in Chapter 7 Wedin takes on the enigmatic claim of Z6, "In the case of things that are primary and spoken of per se, it is clear that the thing and the essence of the thing are the same" (1032a4-6).

Wedin makes Chapter 8, which is primarily a treatment of Z10 and Z11, a discussion of Aristotle on "compositional plasticity," that is, on whether, say, the form of human being might be realized in something other than flesh and bones. "[O]ne could grant," Wedin writes,

that to be a human being is just to be a member of a determinate biological species and so to have a very specific material nature, and yet insist that the form of such creatures be realizable in quite different sorts of matter. Creatures so constituted would not be human beings but they would be entities with similar functional capacities and states . . . From the point of view of philosophy of mind, for example, what matters are the psychological capacities, functions, and states characteristic of persons. Just what these are is determined by a form—the form that happens to be realized in human matter. (340-41)

In Chapter 9 Wedin turns to Z13, which, as he acknowledges, has often been thought to be the most confounding chapter in Zeta. Wedin draws on Z16 to help resolve the aporia with which Z13 ends (roughly this...