An Introduction to the Five Ways of St. Thomas Aquinas, Part 9

The Third Way: The Argument from Contingent Beings

1. In the created order, we see that there are contingent beings – that is, beings that come into existence and go out of existence.
2. If it’s possible for something not to exist, then there would have been at time when it didn’t exist.
3. Given such, then there could have been a time when nothing existed.
4. But, if this were true, then even now nothing would exist, because everything that comes into existence requires a cause. Nothing comes from nothing.
5. There must, therefore, be a Being whose existence is necessary and not dependent on the existence of anything. This Being all people call God.

We know from experience that there are things that come into existence and go out of existence. These are called contingent beings. This simply means that they didn’t have to be. Their existence is dependent on something else that already exists. Everything that comes into existence requires a cause, something that already exists that bestows the gift of existence on the being that previously didn’t exist. If every being were contingent, however, then there would have been a time when nothing existed, for given an infinite amount of time, all possibilities become reality at some point. The possibility of all contingent beings not existing at the same time would then be a reality at some point. But, if this were true, then nothing would ever have come into existence, since nothing comes from nothing. Since we see that some things are in existence, and that there can’t then be an infinite regression of contingent beings. There must be a Being Whose existence is not contingent, a Being Whose existence is necessary, in order to get the ball of existence rolling. This Being is God.

Some will argue that, just because it’s possible for a thing not to exist doesn’t mean that there must be a time when it didn’t exist. Thomas would reject this argument as based on a misunderstanding of contingency. If something is truly contingent, that is, it is possible for it not to exist, than part and parcel of its essence is the option of non-existence. It is, therefore, a being that at some time must not exist. Otherwise, if its existence were essentially guaranteed, it wouldn’t be contingent at all, but necessary. If all contingent beings, by their nature, must not exist at some time, then there could be a time when none of them existed at all. And, if we’re talking about an infinite amount of time then, again, there must be a time when no contingent beings existed. Thomas allows for the existence of other necessary (ie: permanent) beings that are not God, such as angels, but these receive their necessity from another. As well, there can’t be an infinite regression of necessary beings for the reasons made clear in the Second Way. There must, then, be a Being that possesses necessary existence in and of itself, as essential to itself. That Being we call God.

Objections to the Argument from Contingent Beings

Just because it’s possible for something to go out of existence doesn’t mean it will.

This critique would be well founded, if what Thomas meant by “beings that come into existence and go out of existence” meant beings that come and go in all possible worlds, or beings that were logically possible. But, this isn’t what Thomas means at all. Thomas isn’t speaking of what’s possible to exist or could exist logically. He’s talking about what actually exists, according to our experience. Thomas, remember, is starting from the point of what we experience about the world and moving back to the first mover, the first cause, the necessary being. If we look around our world, we certainly experience beings that have built into them the processes of growth and decline. We regularly see things come and go. If, then, something has within its nature the process of decline to the point of no longer existing, it must at some point cease to exist. Otherwise, existing would be necessary to its nature, and it wouldn’t be a contingent being at all. At the other end of the spectrum, these things that come and go can’t bring themselves into existence, for then they would be the cause of their own existence, which is absurd. Neither can there be an infinite regression of necessary beings for the same reason there can’t be an infinite regression of efficient causes. So, there must be a Being whose existence is necessary, a Being whose essence is existence, Who cannot not exist. Otherwise, nothing else would exist, including us, and we wouldn’t be here to argue from contingent beings for the existence of God!

Just because it’s possible, there was a time when no contingent beings existed, doesn’t mean there was actually a time when no contingent beings existed. There could be an infinite regression of contingent beings, where at least one contingent being was always in existence.

Given an infinite amount of time, all possibilities eventually become a reality. So, if it’s possible for there to be a time when no contingent beings existed, then at some time over the course of infinity, there would have to have been a time when there were no contingent beings in existence. Whenever that time occurred, were there no necessary Being to get the ball of existence rolling, it would then require that nothing come into existence out of that void, since nothing can be the cause of its own existence. Nothing comes from nothing.

Why can’t the universe, or some other material being, be the necessary Being?

What Thomas means by “necessary being” is simply one that is everlasting or permanent. As such, there’s nothing in Thomas’ argument to suggest that material beings can’t be necessary. The question is whether or not their necessity is derived from another or of itself. Angels, for instance, are necessary beings, but their necessity is derived from another. Otherwise, we would have to accept the idea that there is an infinite regress of necessary beings, which is impossible.

Recall the discussion on the four causes in the Second Way. The material and formal causes are what give anything its matter and form. Without matter or form, a thing can’t exist in reality. “Pure” matter, that is, matter without form, can’t exist. It’s pure potentiality and never actuality. So, it’s clear that matter, even if necessary, can’t possess its necessity of itself. It must derive its necessity from another, because it can’t give itself form, because it can’t give itself what it doesn’t have. A material being, even an everlasting material being, like the universe or what J. L. Mackie calls the “permanent stock of matter,” (The Miracle of Theism, Oxford: Clarendon, 1982) would still require the existence of a necessary Being that did not derive its necessity from another, or we suffer the incoherence of an infinite regression of necessary beings. The only way to avoid this is to recognize the existence of a necessary Being, Whose being is derived of itself. This Being is God.

Be Christ for all. Bring Christ to all. See Christ in all.