10.3 Proving That the World Is Not Eternal (SCG 2,38)
10.3 Proving That the World Is Not Eternal (SCG 2,38)
Aquinas concludes SCG 2,37 by summarizing his findings concerning the thesis that the world has always existed. He writes: “In the light of all this, then, it is clear that nothing stands in the way of one’s holding that the world has not always existed—a truth which the Catholic faith affirms.”19 Yet how should we respond to the claim that it can be proved that the world is not eternal? In SCG 2,38 Aquinas notes six arguments in defense of this claim, though he finds none of them persuasive.20
The arguments noted by Aquinas run thus.
1. If God causes all things, he must precede in duration the things that he produces.
2. If all being is created by God, it cannot be made from something and must be made from nothing. So it must have being after not being.
3. “An infinite number of things cannot be traversed.”21 But if the world has always existed, an infinite number of things would have been traversed by now.
4. One cannot add to the infinite. However, on the supposition that the world has always existed, infinity would seem to be added to daily as one event or process follows another.
5. If the world has always existed, there can be an infinite series of efficient causes. But there cannot be such a series.
6. If the world has always existed, there would exist an infinite number of immortal souls of people who died in the past. But there cannot be such a number of souls.
Aquinas rejects argument 1 here by saying that an agent need not necessarily precede the effect that results from its operation. He agrees that there is such preceding when it comes to agents that bring things about by a process of change having a beginning and end initiated by an agent that exists as the process of change starts. But, he adds, things can also act instantly so as to bring about an effect that does not follow from a process of change in that on which they are acting.
In response to the second argument, Aquinas has this to say:
If the proposition (a) something is made from something is not admitted, then the contradictory of it which must be given is: (b) something is not made from something, and not (c) something is made from nothing, except in the sense of proposition (b). And from this it cannot be concluded that something is made after not-being.22
In other words, so Aquinas is arguing, while God may creatively make all beings from nothing, all that this means is that God makes creatures, but not out of anything.
Aquinas deals with argument 3 by saying that, although the infinite does not exist all at once, it can exist successively, meaning that, in a certain sense, any infinite is finite. For example, any given revolution of the earth around the sun is finite, even if there are or have been an infinite number of such revolutions.23 And such finite revolutions can be over and done with regardless of how many of them have occurred. Here Aquinas seems to be saying that an infinite number of past and distinct processes can, taken individually, each be completed, even if the world never had a beginning, and even if one cannot, accordingly, speak of a first process resulting in a final one.
Concerning argument 4, Aquinas’s line is that “there is no reason why an addition should not be made to the infinite on that side of it which is finite.”24 Here Aquinas seems to mean that, even if the world never began to exist (if nothing in it was ever first), it does not follow that there cannot have occurred successive comings-to-be in the world of finite things. He writes: “From the supposition of the eternity of time it follows that time is infinite in relation to the prior but finite in relation to the posterior; for the present is the terminal point of the past.”25
With respect to the fifth argument, based on the idea that there cannot be an endless series of efficient causes, Aquinas draws on the distinction I noted in chapter 3 between a causal series per accidens (in which things act in succession as merely preceding each other in time), and one per se (in which there is a single cause running through the whole series). He agrees that there cannot be an infinite series of efficient causes insofar as the causes in the series act as instruments of a single cause. But he sees no reason why there cannot be an endless series of causes each of which depends only on the action of something prior to it in time, as, say, people who are born depend on their parents having copulated. Or, as Aquinas writes: “It is accidental to Socrates’ father whether he is another man’s son or not. But it is not accidental to the stick, in moving the stone, that it be moved by the hand; for the stick moves just so far as it is moved.”26 According to Aquinas, there cannot be an infinite regression when it comes to causes that are all instruments of some primary cause and whose causing depends on the activity of something other than them. Yet there can be an infinite regression when it comes to causes that are not, in this sense, instruments through which something is working that enables or empowers them to cause as they do.
When it comes to argument 6, Aquinas admits that it is not easy to refute. However, he goes on to say, that is because it depends on how we think of human souls and their survival after death. After all, Aquinas reasons, the argument is not going to work if we suppose that human souls do not survive at all, or do not survive intact, when people perish. Nor is it going to work if we suppose that human souls return to inhabit bodies. In short, thinks Aquinas, argument 6 is hardly a knockdown one since it takes many things for granted. Here, I take him to be saying that the argument is too vague to be considered as a demonstration.