I have been asking, in effect, on what grounds Aristotle in Met. L holds that the Prime Mover is an intellect. Does he argue for this directly, e.g. on the grounds that the Prime Mover lacks potentiality, or does he do so through an analogy with the human mind--so that here metaphysics depends upon psychology (a branch of physics)?
Aquinas in his commentary has a surprising answer to this question. I'll explain it to you.
He attributes to Aristotle the following argument:
- The Prime Mover moves without being moved.
- But something can move without itself being moved, only through its being an object of intelligence and will.
- Thus, the Prime Mover moves through being on object of intelligence and will.
- The First Heaven is the first thing moved by the Prime Mover.
- But what is moved by something as being an object of intelligence and will, has intelligence and will.
- Thus the First heaven has intelligence and will.
And its course of life is like the best which we enjoy for a short time; for it is always in that state, though this is impossible for us. For its operation is also pleasure. (That is why being awake, sensing, and understanding are most pleasant, and hopes and memories are pleasant because of them.) Now undersanding in itself has to do with what is best in itself, and the highest type of understanding has to do with what is best to the highest degree. ...According to Aquinas, after Aristotle thus establishes results about the intellectual life of the First Heaven, he then arrives at similar results about the Prime Mover through a fortiori arguments. Indeed, Aquinas thinks that Aristotle does not begin talking about the Prime Mover's intellectual activity (as opposed to that of the First Heaven) until the mention of 'God' at 1072b25:
Therefore, if God is in that pleasurable state in which we sometimes are, this is wondrous; and if He is in that state in a higher degree, this is even more wondrous; and He is in that state.Aquinas understands this as: It would be wondrous if God were in the same state as the First Heaven, but in fact, since he is the cause of the First Heaven, he is in an even more pleasurable state, which is even more wondrous.
So Aquinas attributes a bootstrapping argument to Aristotle: argue first that the Prime Mover is an object of intelligence and will; then argue that the First Heaven must have intelligence and will; then use human psychology to fill out, by analogical reasoning, our account of the intellectual life of the First Heaven; then use a fortiori arguments to reach proportionate conclusions about the Prime Mover. Very clever.