ABSTRACT
Some of the divergences we find between different seventeenthcentury philosophers’ conceptions of substance are traceable to different emphases they place on various features of the original Aristotelian doctrine of substance. In one of his important early works, the Categories, Aristotle introduces the notion of a ‘primary’ substance, by which he means, roughly speaking, a concrete, individual, persisting thing-such as a tree, a rock, a house or a man. (It is important, then, to see that this use of the term ‘substance’ is considerably removed from its most common present-day use, to denote a kind of stuff, such as water or potassium chloride-though we shall see some connections emerge in due course.) Aristotle calls such things ‘primary’ substances in order to distinguish them from what he calls ‘secondary’ substances, by which he understands the general kinds (or species or genera) to which those things belong. Thus the kind man is the ‘secondary’ substance to which the individual man Socrates belongs, and Socrates himself is a ‘primary’ substance.
