If you actually look at Aristotle’s arguments against an infinite regress of motion in section one of book seven of the Physics he really only makes one argument. First he points out that in the sequence of A being moved by B being moved by C etc… the time it takes for A to move is finite, but the motion of the entire series is infinite, and you can’t have an infinite motion in a finite amount of time.
The problem with this kind of argument is that it only works if the motions are simultaneous. If B occurs before A and C occurs before B etc… then although you do have an infinite, because each part of it occurs at a different time it is only a potential infinite rather than an actual infinite.
Here is the way Thomas answers in the Summa Contra Gentiles, Book 1, Ch 13:
[11] The second proposition, namely, that there is no procession to infinity among movers and things moved, Aristotle proves in three ways.
[12] The first is as follows [VII, 1]. If among movers and things moved we proceed to infinity, all these infinite beings must be bodies. For whatever is moved is divisible and a body, as is proved in the Physics [VI, 4]. But every body that moves some thing moved is itself moved while moving it. Therefore, all these infinites are moved together while one of them is moved. But one of them, being finite, is moved in a finite time. Therefore, all those infinites are moved in a finite time. This, however, is impossible. It is, therefore, impossible that among movers and things moved one can proceed to infinity.
[13] Furthermore, that it is impossible for the abovementioned infinites to be moved in a finite time Aristotle proves as follows. The mover and the thing moved must exist simultaneously. This Aristotle proves by induction in the various species of motion. But bodies cannot be simultaneous except through continuity or contiguity. Now, since, as has been proved, all the aforementioned movers and. things moved are bodies, they must constitute by continuity or contiguity a sort of single mobile. In this way, one infinite is moved in a finite time. This is impossible, as is proved in the Physics [VII, 1].
[14] The second argument proving the same conclusion is the following. In an ordered series of movers and things moved (this is a series in which one is moved by another according to an order), it is necessarily the fact that, when the first mover is removed or ceases to move, no other mover will move or be moved. For the first mover is the cause of motion for all the others. But, if there are movers and things moved following an order to infinity, there will be no first mover, but all would be as intermediate movers. Therefore, none of the others will be able to be moved, and thus nothing in the world will be moved.
[15] The third proof comes to the same conclusion, except that, by beginning with the superior, it has a reversed order. It is as follows. That which moves as an instrumental cause cannot move unless there be a principal moving cause. But, if we proceed to infinity among movers and things moved, all movers will be as instrumental causes, because they will be moved movers and there will be nothing as a principal mover. Therefore, nothing will be moved. "
I like 14 and 15 better because they are easier to understand. So it is clear that there can be no infinite regress and there has to be an Unmoved Mover that is Pure Act ( as Aristotle himself implies, since an Unmoved and Unmovible Intelligence, must be Pure Act). If there is no Unmoved Mover, then there is nothing else either, which is clearly false.
Even in terms of the power of the cause being passed down there is no actual infinity with an infinite causal chain.
Aristotle and Thomas just proved that an infinite regress is impossible. How is your statement here any different? I don’t see the difference.
Allow me to demonstrate this first by means of a finite causal sequence. Suppose A is moved by B which is moved by C. The causal power of C moves B and is expended, and the causal power of B in turn moves A. Or alternatively one could say that the causal power of C is converted into the causal power of B which then moves A. The essential point here is that A doesn’t receive an inherited effect of everything in the causal chain but is only moved by the causal power of B.
Yes, but C intends to exsert only that particular power to achieve the desired, particular effect. This is not to deny that the intervening instruments may have other powers which have not been exsrted. I see no problem here…
In the case of an infinite sequence that is not simultaneous we have A being moved by B being moved by C etc… Because the causal power of each term in the sequence is expended (or converted if you prefer) A will not be moved by an actually infinite inherited causal power of B+C+D+… but is instead only moved by the causal power of B, even in the case of an infinite sequence, and so Aristotle’s argument fails.
I don’t see how you can have such an infinite sequence. I think Aristotle proved that any such infinites series would consist of movers and moved moving simultaneorsly as one motion.
I think I am running out of space. Will continue on another post.
Linus2nd