ABSTRACT
One of the greatest metaphysical insights that Aristotle contributed to the history of philosophy is that objects may be partitioned in two ways: into parts and into abstracta. The latter kind of division has not received due attention among contemporary extensional mereologists (who advocate division into parts only), and even in neo-Aristotelian quarters. In addition to clarifying which type of part is relevant for understanding Aristotle’s hylomorphism, I urge that we need to critically re-examine certain assumptions we make in our study of Aristotle’s theory of substance. Among the questions I raise in this chapter are these: Is there a primary matter-to-form ‘relation’ in a substance? Is the ‘relation’ between matter and form in a substance analogous to that of potentiality to actuality? Does Aristotle’s theory of substance deliver a sound account of substantial unity? I will argue that it doesn’t, and supply an account, which derives from principles within Aristotle’s metaphysics, but differs from the account given to us by Aristotle. I will argue that Aristotle came very close to having a full account of the oneness of a substance, but fell short of it. He unified matter and form in a substance definitionally, but did not explain and justify the oneness of the definition.
