Aristotle on Substance and Unity

In this article I argue that in H 6 Aristotle's main concern is to explain both the unity of form and the unity of composite substance. Commentators have taken H 6 as concerned with either the unity of form or the unity of the composite substance, but not with both. But there is no exclusive "either/or". The correct position is "both/and". I argue that proper identification of the aim of the inquiry of H 6 indicates that Aristotle is concerned with both the unity of form and the unity of composite substance. On my interpretation, Aristotle's intention is to defend the theory of substance-as-cause by dealing with a possible problem. The possible problem arises from a combination of (a) speaking about the parts of form and the parts of composite substances and (b) the principle that parts of a whole need a unifying cause in order to be one and not many. Aristotle has (a') spoken about the parts of form and the parts of composite substance. He has also (b') claimed that the parts of a whole have to have a unifying cause in order to be one and not many. Do form and composite substance, then, have a unifying cause for their unity? Aristotle sees a possible problem arising from thinking that they do. If both form and composite particulars need a unifying cause, form cannot be substance, and composite substances, as composites of form and matter, cannot be unities, but must be mere heaps of matter. The problems of theunity of form and the unity of composite substance are similar, then; and the unity of each must be accounted for. Not surprisingly, the problems being similar, the solutions to those problems, the accounts of the unity of form and composite substance, are similar as well. The two are thus discussed together in H 6. It is there that Aristotle provides such accounts. H 6, then, concerns both the unity of form and the unity of composite substance