I don't know why, but I have always been drawn to cosmological arguments. Even when I was not a committed Christian, I still believed in God based on these kinds of arguments. As a result, I'm always looking for ways to improve how we enunciate the argument. My last post covered Thomas' basic metaphysical proof of God's existence. The one I'll brielfy cover in this entry is perhaps the oldest of the cosmological arguments - the "argument from motion." There are two ways that come to mind that we might formalize the proof. They are as follows:
1. Everything in motion is moved by another.
2. The series of movers either proceeds to infinity, or has a first mover.
3. The series cannot proceed to infinity.
4. Therefore, there exists a first mover.
1a. Everything in motion is moved by another.
2a. The universe is in motion.
3a. Therefore, the universe is moved by another.
I won't go into great detail with this argument, since I have done so in past entries. Here is a succinct defense of each premise. (1) is supported inductively by our observations. Whenever something changes (re: "is in motion"), it passes from a state of potentiality to actuality by something that actualizes it. For example, a pot of water will contain boiling water if and only if it is heated. Once again, quantum fluctuations are not an exception to the rule, given that the fluctuations arise out of the energy already contained within the quantum vacuum.
(2) provides us with our two legitimate options. (3) claims that the series of movers moving something right now, or at any finite period of time, cannot be infinite. The reason for this is that it would require an infinite series of movers to move within a finite period of time. Yet, it would take infinite time for an infinite series to move anything at all. Hence, the series of movers must be finite, and must be ontologically preceded by a first mover. Therefore, the conclusion is justified in stating that a first mover exists.
Now, we know that everything that changes is composed of both actuality and potentiality. Yet, the first mover cannot itself be moved; otherwise, it wouldn't be first, which is a contradiction. As a result, the first mover cannot be composed of any potentiality, since only changing things are composed of potentiality. Therefore, the first mover is pure actuality. From this, all of the other God-attributes are inferred.
Let's move on now to the second form of the proof.
(1a) is identical to (1), so we'll focus our time on (2a). The common objection to the second premise is that it commits the fallacy of composition. I've already touched on this before, but I'll reiterate that there are two types of compositions: incidental compositions and essential compositions. The former are fallacious, whereas the latter are sound. It seems unambigious to me that (2) falls into the category of an essential composition, since everything within the universe is connected in some sense. For instance, every part of the universe is changing, but is still intelligible.
Now, how do we infer that the mover of the universe is like the first mover above? The solution is fairly simple. Everything that changes is composed of potentiality; and, only bodies contain composition. Whatever moves the universe must be transcendent with respect to the universe, so it is simple, rather than composite. On these grounds, the mover of the universe must be purely actual, and therefore, immutable.
Moreover, why should one accept the idea that everything within the universe is moved by another, but that this is not true of the universe as a whole? This appears to me, given the weakness of the objection that this is a composition fallacy, that this objection commits the fallacy of special pleading. Why should we make such a grandiose exception for the universe as a whole? Without any plausible alternatives, I don't see any way out of the conclusion that there is a first mover.
It is also important to keep in mind that this argument is consistent with an infinitely-old universe. Aristotle defended it, after all.