Let's say that some being A is changed to being B (example: lion burned to ashes, cold metal turned to hot metal, etc.).
Thesis. It is impossible that being A is changed to being B.
- Suppose that being A is changed to being B.
- That means that the last moment of existence of being A is the first moment of the existence of being B.
- But this gives us a contradiction, because in the last moment A is A, but also, because that moment is the first moment of existence of being B, A is also B, and that is impossible.
- One may say that when A becomes B, that the last moment of existence of A is not the first moment of existence of B.But this also is impossible. The reason is that if those two moments do not coincide, then there is some time between them. From that would follow that what really happens is that A becomes non-being and that then from non-being B arises. But there would be no sufficient reason for why from non-being would then B arise and not some other being.
Question. What is wrong with the argument?
I am primarily interested in the response from the viewpoint of Aristotelian - Thomistic philosophy, but if someone has any good points to make he is welcome to answer. I was motivated to pose this argument by looking at Aquinas De Potentia Dei q.3.a.1.obj.10. However, I am unable to answer my question from his replay to objection.
Edit 1 (It would seem that admitting division of being in being in act and being in potency does not solve the problem.)
Let us say I admit division of being in potency and being in act. How does that resolve my problem? I can form my argument like this:
1) A is being in act and B is being in potency.
2) That means that there is a subject S which has (at least) two ways of existing (A and B) of which A is actual and B potential.
3) Let us say that S changes its way of existing, ie. it goes from A to B.
4) Either the last moment of actual A is the same as the first moment of actual B or it is not.
5) If it is, then the subject S is A in act and B in act; and that gives us a contradiction.
6) If it is not, then there exists some time in between during which S exists in pure potency or in some other actual way C.
7) But if S is pure potency, then S is not distinguished from non-being. In this case, the change to B is impossible because it would require that non-being becomes being.
8) But if S is not pure potency, but exists in some way, then we have a change from S existing in A actually to S existing in C actually (ie. transition from existing in A way to C way). But this does not solve a problem, but only pushes it back one step further, because now the question is: how we have change from A to C?
So it seems that admitting being in act, being in potency and matter which changes does not solve the problem (or at least I, unfortunately, do not see how it solves the problem). Also, it seems that the agent affecting the change is not relevant for the problem (or at least I do not see how he is); for even if I admit him, I do not see what changes in the argument.