Aquinas on Powers - One Interpretation (2)

In the last post, I mentioned that part of me thinks Aquinas's arguments about powers really boil down to a simple argument from identity: if A and B are identical, then anything true of the one must be true of the other, but since this is not the case with my soul and its powers (I always have soul, for instance, but I am not always thinking), it follows that my powers that are based on my soul must be different from my soul itself.

But one could buttress this argument even further. For we might point out that one of the characteristics of powers is that they can only be exercised in particular circumstances. For instance, wine glasses can be broken when they are dropped on a hard floor (in a world consisting only of soft cushiony floors, wine glasses would not break when dropped). Wine glasses might also be broken when they are struck with a swinging baseball bat. And so on.

We might then point out that each power of my soul is no different. Each power of my soul requires a different set of circumstances for its exercise too. For example, compare my power of sight with my power to remember things I have already seen. According to Aquinas, both of these are powers of my soul. However, it would seem that the former power can only be exercised in one set of circumstances (I must have my eyes open, there must be sufficient light, and so forth), whereas the latter power requires an entirely different set of circumstances (e.g., that what I saw before was adequately stored in my memory banks, and so forth).

Consequently, we might make the following inference: since each power of my soul requires a different set of circumstances for its exercise, it follows that each power of my soul must be distinct from every other power of my soul, and from my soul itself. Otherwise, I could not exercise one of my soul’s powers without exercising all of them at the same time. So, one might say, surely it follows that my soul and each of its powers must be distinct from each other.