10.5 Some Comments on SCG 2,30–45
10.5 Some Comments on SCG 2,30–45
Ancient and medieval thinkers devoted a lot of time to discussing the question “Has the world existed for ever?”46 Aquinas was among their number, and what he says in SCG 2,31–38 is one of his more detailed discussions of the question. But is Aquinas right in what he argues here?
Like all of his Christian contemporaries, Aquinas believed that the universe began to exist. He did so on the basis of Genesis 1 and because of what the Catholic Church officially taught from the time of the Fourth Lateran Council.47 Yet Aquinas did not think it inconceivable that the universe might never have had a beginning, while some of his contemporaries thought it possible to prove that it had to have had a beginning. So do we have reason to think that the universe must have had a beginning? And does Aquinas say enough to show that the universe might not have had a beginning?
You may think that nothing Aquinas argues serves to show that the universe might never have had a beginning since it now seems to be scientifically established that it did. Here, of course, I am referring to the big bang theory, which is currently accepted by many scientific cosmologists.
Hence, for example, Richard Swinburne can say: “There is no doubt that the models best substantiated today are ones which show the Universe expanding from a ‘big bang’ some 14,000 million years ago. These models successfully predict not merely the density and rate of recession of the galaxies, but the ratio of the various chemical elements to each other and to radiation in the universe, and above all the background radiation.”48
Of course, even if we accept the big bang theory in some form, there presumably remains the possibility that the big bang did not amount to an absolute beginning of things and might in some way have followed what preexisted it materially. Defenders of the big bang theory would typically say that they have given us reason to suppose that we can trace the history of the universe to a certain point. Yet is that enough to warrant us supposing that there was, in no sense, a material “before” prior to that point with respect to which the big bang might be an effect or result? As far as I can gather, it is not at all uncommon for contemporary cosmologists to admit that they are ignorant concerning whether the beginning of the universe as we know it, considered as expanding and filled with matter that has cooled, marks an absolute physical beginning.49
On the other hand, though, the universe, as Aquinas conceived of it, does seem to have had a dateable beginning. Aquinas’s cosmology takes the earth always to have been at the center of a stable arrangement of things in which stars form a perimeter. So you may think that his claim that the universe cannot be shown to have had a beginning has been falsified by science since his day since it rests on a view of the universe that is now antiquated. Suppose, however, that we forget about scientific arguments concerning the start of the universe and focus on philosophical ones of the kind in which Aquinas engages in his discussion of the eternity of the world in SCG 2. Who wins when it comes to the question “Can it be proved that the universe had a beginning”?
As Aquinas notes, it has been argued that the universe must have had a beginning since if past time is infinite, an infinity of events would (impossibly) have to have elapsed or been traversed before today. Yet this argument, as J. L. Mackie observes, “just expresses a prejudice against an actual infinite.”50 As Mackie goes on to say: “It assumes that, even if past time were infinite, there would still have to have been a starting-point of time, but one infinitely remote, so that an actual infinity would have had to be traversed to reach the present from there. But to take the hypothesis of infinity seriously would be to suppose that there was no starting-point, not even an infinitely remote one, and that from any specific point in past time there is only a finite stretch that needs to be traversed to reach the present.”51
As you will realize, this is what Aquinas argues in response to the third argument he discusses in SCG 2,38. You might reject it by saying that there is something problematic with the claim that the universe never had a beginning since, if that were correct, then it would, in principle, be possible for someone truly to say “I have just finished counting backward from infinity.” Yet counting involves taking a starting number, while if the universe never began to exist there is no starting number from which to start counting backward.
You might say that an infinite number of past years cannot have occurred before the present since that would mean that infinity has an end. Yet an infinite number of past years might have elapsed if, in an infinite number of past years, there is no beginning or starting year. And if there is no beginning or starting year, then “we cannot imagine that the beginningless series of past years has been subjected to counting in any straightforward way, for it has no first member to match the first number used in counting.”52
You might say that what is infinite cannot have an end and that the past ended just now. But there is no reason to suppose that an infinite series cannot have one end. After all, the series of positive whole numbers has an end at zero.
You might say that, while there might be an infinity of future events with no end to them, there cannot have been an infinity of past events since an infinite future is potential while an infinite past must be completed by now. Yet to suppose an infinite number of past years is not to suppose that they have two termini, one of which is the present moment and one of which is way back in time. Past years do not start from now, even if our thoughts about past years do so; and if the universe had no beginning, then past years did not have a starting point and do not have a finishing point, meaning that today could have arrived after infinite past time and that there can be days or moments after today. If past time had a starting point, then it would be impossible for an infinite number of days to have been fitted in between then and now. But if there is no starting point to the history of the universe, there is nothing to be fitted in between a first point and today.
This is not a book on cosmology and infinity, but I would like to conclude this chapter by suggesting that it is not obvious that to suppose that the world never had a beginning leads to manifest absurdities and that a case can be made in defense of Aquinas’s SCG claim that it has not been proved that the world had a beginning.
As I have noted, however, Aquinas, unlike Aristotle and many ancient Greek philosophers, did think that the universe began to be.53 Contrary to people who assume that “Does God exist?” means “Was there a God who got the universe going some time in the past?” Aquinas thinks that God exists as making things to exist at any time, and whether or not the world began to be. So Aquinas’s natural theology in the SCG is not committed to theological claims to the effect that the universe had a beginning. In Aquinas we have a theologian who is taken by many Christians to be a highly orthodox thinker. It is not for nothing that he has been proclaimed by the Catholic Church to be a doctor of the faith. We might, therefore, wonder whether it is true, as some have said, that one cannot be a Christian if one thinks that the universe never had a beginning.
Once again, though, Aquinas did think that the universe began to exist. And he takes it to contain creatures of different kinds. Also, as I have shown, in SCG 2,5 Aquinas says that he intends in what follows to write (1) about the bringing forth of things into being, (2) about distinctions among things, and (3) about “the nature of these same things, brought forth and distinct from one another, so far as it is relevant to the truth of the faith.”54 In SCG 2 Aquinas deals with (1) and (2) in chapters 6–45. In SCG 2,46 Aquinas begins to follow up on his promise concerning (3). So let us now follow him as he does so.