Prime Matter as Persisting

 As I mentioned in my last post, I do not think that parcels of prime matter persist for longer than an instant. How then can prime matter fulfill its traditional role (from Physics, Book II) of being the enduring substrate for substantial change: that is, being the persisting subject that is successively informed by one substantial form and then by another? In my view, it is not prime matter as such that persists, but there is a derived entity, which we can call "persisting matter" that does do so. Persisting matter is an example of what Roderick Chisholm called an 'ens successivum'. That is, a gob of persisting matter is fundamentally a series of packets of instantaneous prime matter that are tied together by a series of causal connections. These causal connections constitute what Hans Reichenbach termed a 'genidentity' relation between pairs of packets of prime matter. Two packets of prime matter count as successive versions or temporal parts of persisting matter when they are linked together by an appropriate causal relation.
 
When one substance is corrupted and another generated in its place, there is always a third entity involved: the agent of the corruption/generation. This third entity must be disjoint from the other two--neither generated nor corrupted at the moment of substantial change, but persisting through it. The agent acts upon the prime-matter packet that constitutes the corrupting substance, replacing it with a new prime-matter packet that constitutes the new, generated substance. This causal relation ties the two packets together into a single stream of "persisting matter". In the natural order, corruption and generation cannot occur unless both the old and new substance contain prime matter, and some external agent causes the replacement of the old matter by the new.
 
Let's consider a less drastic case of substantial change: substance A grows by incorporating part of substance B (which shrinks as a result). In this case, there are just two substances involved, since A can be the agent of its own growth, acting on part of the prime matter of B, causing it to be replaced by new prime matter that constitutes the new part of A. Again, this causal connection will tie together the old packet of prime matter and the new. We don't need a fundamentally persisting entity at the level of prime matter.