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Question 46. The beginning of the duration of creatures.” On the one hand, he answers in article 1, "It is not therefore necessary for the world to be always; and hence it cannot be proved by demonstration. " But in the second article he answers “By faith alone do we hold, and by no demonstration can it be proved, that the world did not always exist.”
So am I right in understanding that St. Thomas says that you cannot determine by reason whether the universe is eternal or not? But he also says that an infinite series of causes into the past is impossible, so doesn’t that prove that the universe is not eternal? If someone could summarize what he’s saying in these three articles I would much appreciate it.
This is an excellent question!
Yes, Aquinas very strongly holds to the view that the creation of the world, ex nihilo, is an article of faith alone. It cannot be proven by any reason whatsoever. And yes, at the same time he does prove the existence of God or a first mover by showing that a series of infinite causes is impossible. These two statements do not contradict each other. Let me try to explain.
All five of Aquinas’s proofs assume that the world actually
is eternal. He does not think it can be proven either way, whether the world began, or whether it always existed. You can read his commentary on Aristotle’s Metaphysics or Physics I can’t remember and see that he said that Aristotle’s proofs were not absolutely demonstrative, but only relatively so - i.e. he proved that it was impossible to conclude the world began, but never positively proved it had always existed. Now, the reason it is hard to understand how Aquinas could hold that the world is eternal and still claim his proofs were valid is because you’re thinking of the first cause as a
temporally prior cause. A temporal cause however could really stretch back infinitely, as Aquinas says here in the Summa and in Questions 44 and 45. But an infinite set of temporal causes still require a first cause, because if all temporal causes are caused by another, they are not by nature causes, but only effects. In other words, imagine an infinite set of dominos. The nature of each domino is to fall
after it has been hit. This captures perfectly the principle of causality Aquinas is employing - namely, that every effect must have a cause. Every falling domino must have a previous domino to hit it. Suppose you want to say “suppose it is just in the nature of the domino to fall?” Well then, it may be, but notice, you have proven a first cause: namely, whatever falling domino has in its nature causality. It cannot be, if a domino has, in its nature, causality, that it can get it from another, and therefore there could be no infinite set of dominos whose nature was necessarily falling or necessarily causal, since each domino in the set would not fall necessarily, but only insofar as it was hit by the previous domino. Now, as I say, an infinite amount of dominos can
actually be falling; this is true, and would be the case if the world was eternal. But the only way they can all fall - that is, the only way they can move from a *potentially *falling set to an *actual *falling set - is if they are caused to do so by some causally (not necessarily temporally) prior agent.
The key to understand Aquinas’s arguments is not to assume the first cause is a temporal cause, but rather a *logically *or *naturally *cause (an example would be, if you are sitting in a chair, the chair is causally prior to your ability to sit; it is not temporally prior in the present instant of your sitting, but, without the chair being there, you could not be sitting it in). A cause which, as its nature, has the necessity of causality. Aristotle described this cause like a beautiful painting which, in its very nature, draws all people to come see it. It is not caused or moved by anything itself. Rather it does all the moving.
That, then, is the nature of the first cause. The proof shows that it must necessarily be unmoved in itself. Otherwise, we must look elsewhere for what moved it. Eventually, since nothing moves itself, and all things in motion are moved by another preceding mover, we must come to a thing that only moves, and is not itself moved.
Hope that helps some.
