Proving the Existence of God: St. Thomas Aquinas’ “Five Ways” Examined (Part 2)

Arguments 1-3: Hey Look! Stuff! Where'd It Come From?

At the end of the introduction, I mentioned that St. Thomas bases his arguments upon facts of the world around us—facts that are undisputed by modern science. There are a number of websites out there that try to dispute with Thomas claiming that his Five Ways are mired in an Aristotelian concept of the universe, and therefore aren't valid because of the advances of modern science. However, the very genius of Thomas' arguments are their very simplicity. The principles espoused in them are not dependent upon a particular understanding of the universe, be it Aristotelian, Cartesian, Newtonian, or that of contemporary physics. Things still move and change, they still cause effects, they still depend on other things, they still vary in degrees of perfection, and they still act toward definite ends. Our understanding of how these things occur may be more developed and nuanced, but the philosophical conclusions that result from them are just as inescapable.

The first three arguments, or ways that St. Thomas puts forward, are the argument from motion or change, the argument from causation, and the argument from contingency. Their formulation is very similar, so that they are often viewed as being the same argument phrased differently. This isn't entirely accurate, because each one begins with a different starting point. They do dovetail, however, and so we will treat them together.

The arguments run essentially thus:

1) When we look at the world around us, we see that things a) move or change, b) have a cause, and c) are contingent, that is, not inherently necessary.

2) Something else must be responsible for the effects listed in #1.
i) There must be a) a reason for a change, b) a cause for an effect, and c) something necessary to be contingent upon.
ii) A thing cannot a) move itself, b) cause itself, or c) be contingent upon itself.
iii) There cannot be an infinite regress of a) movers, b) causes, or c) necessary things.

3) There must be therefore a) an unmoved mover, b) an uncaused cause, and c) a truly necessary being. This we call God.

Clear as mud?

Let's look at it a little more closely—specifically the notion of motion (or change). What do we mean when we say that a thing doesn't move itself? I moved myself to type this up, didn't I? Well, no, not exactly. Typing this article is the result of a long process of different things acting upon me, and my acting in response. I could hardly detail the myriad chain of events that lies between my fingers pressing keys and the letters instantaneously appearing on the screen. And my fingers move because of the muscles that pull them, which are linked to my nervous system, which receives signals from my brain in response to my mind telling it to type as I try to find ways to express St. Thomas' arguments in a convincing and compelling way. This act of thinking came about because I realised I had a lot to write and a deadline to have it written by. This deadline was imposed by the fine owners of Catholic Chapter House, namely Theresa, after a series of conversations about when best to run the series, which was prompted by my proposal to write such a series, which was prompted by my reading a couple of good books on the subject, such as, for example, Fr. Thomas Crean, OP's God Is No Delusion. I read that book because I bought it from Catholic Chapter House the day I volunteered with David selling books at a local parish. I was prompted to buy and read that book because of conversations with my brother and a good friend of mine, both of whom are atheists. And on and on the chain of causality goes. Every action, every movement, every change requires an explanation. It requires a cause, a mover. Something prompted me to talk to my friend about why he doesn't believe in God. Something prompted him to stop believing in God. Every change is precipitated by another change. Every effect is precipitated by a cause, which is itself an effect of another cause. Every thing in this universe is somehow dependent upon something else for its existence. If we had the time, the ability, and the attention span, we could trace each cause back to the ones before. In doing so, there are two possibilities: 1) the chain of causality would go on forever into eternity past; or 2) we would come at last to a First Cause, an Unmoved Mover, and a Truly Necessary Being.

When reading rebuttals of St. Thomas' Five Ways in preparation for this article, the most common was simply, "Why can't we have an infinite regression?" Apparently, many suppose that the denial of infinite regression is predicated upon our inability to comprehend infinity, and therefore we, and St. Thomas, concluded that it must not be true. This objection is baseless for two reasons: First, St. Thomas (and all Christians) are advocating for an infinite God, so clearly our issue isn't with the concept of infinity. Second, it's not about our inability to comprehend infinity. The problem with an infinite regression is simply that nothing would actually happen. For an infinite regression to work, a thing would have to cause itself. In fact, everything would have had to cause itself and everything else caused by it, all the way down the chain of events. In technical terms, a thing would have to be both potential and actual at the same time. Consider the case of the acorn and the oak tree. The acorn will grow up to be a mighty oak, but while it is but an acorn, it is only potentially an oak tree. It is actually an acorn. Only when it is an oak tree will it actually be an oak tree, but then it will no longer be an acorn. That's what change is. If infinite regression is posited, it is the same as saying that the acorn is the oak tree, that it essentially causes itself to be the oak tree—that there is no distinction between the potential and the actual. This is manifestly absurd. In the chain of cause and effect, there must be a cause that was itself not caused, a mover that was itself not moved, a truly Necessary Being.

This is why, in part 1, I stressed that God is not a thing like every other thing. The Unmoved Mover, the Uncaused Cause, the Necessary Being, is unlike every other thing in that there is no potentiality in God. He is entirely and eternally Actual, and is, indeed, pure Act. He does not change, because He is always acting, always moving, always causing, always Necessary. This is why the flippant question, "What caused God?" has no meaning, because God has no potentiality. Nothing caused God. God is. As we saw last time, He is the very ground of existence. He is existence itself. He is not simply the beginning of a long line of cause and effect, either, but is immediately and unchangingly the efficient cause of every effect. He is the One Necessity upon which every contingent thing depends.


(Category: Theology Proper: God in general.)