In the previous chapter, we said that the principal argument for God’s existence in the eyes of most philosophical theists is the cosmological argument, and we explained that the cosmological argument makes no claims with respect to the question of whether the cosmos had a temporal beginning. The cosmological argument concludes that the cosmos must be created because it cannot be the cause of its own existence. It claims, not that creation is something that happened long ago and was finished, but rather that creation is a continuous and ongoing event. At every moment that it exists, the world has had, does have, and will have a creator, at least according to the cosmological argument.
Nevertheless, some philosophically inclined theists have attempted to show that God exists by first showing that the cosmos had a beginning point in time. This argument was articulated early on within the context of Islam by those who were developing theological argumentation, known in Arabic as kalaam. As a result, it has become known even in modern times as the kalaam argument for God’s existence. The argument was taken over within the Christian world at various times; in the Middle Ages, its most famous advocate was Saint Bonaventure. The kalaam argument does not necessarily conflict with the cosmological argument; indeed, it is logically compatible with the cosmological argument. It is, however, distinct from the cosmological argument. The two arguments are quite separable and do not imply each other, even if they do reach similar conclusions about God’s existence.
A. The Basic Claims of the Kalaam Argument
In modern times, the most visible of the defenders of the kalaam argument is probably William Lane Craig, who has reconstructed the argument as follows:
1. Whatever begins to exist has a cause.
2. The universe began to exist.
Therefore, the universe has a cause.
From this simple reconstruction of the argument, we can see that the argument is based squarely on two premises or principles. Why do advocates of the kalaam argument accept these principles?
Let us consider the second premise first. In order to establish the truth of this premise, the advocates of the kalaam argument typically proceed in an indirect manner: they try to show that the contradiction of the premise must be false, and hence the premise itself must be true. This is a common argumentative strategy, but it may seem confusing at first. If any statement, say P, can be shown to be false, then the contradiction of that statement, not-P, must be true. So, if the contradiction of the second premise, “the universe began to exist”, can be shown to be false, then the second premise itself must be true. Now, the contradiction of “the universe began to exist” is clearly “the universe did not begin to exist” or “the universe had no temporal beginning.” But if the universe had no temporal beginning, then “the universe is infinite with respect to past time.” Can this statement be proven to be false?
In order to answer this question, it is first necessary to be clear regarding what sort of infinity we are talking about. In chapter 7 we applied the word “infinity” to space, saying that, with respect to God, spatial infinity means that God is simply “outside” the category of space. In chapter 7 we also used the word “eternal” to refer to temporal infinity and suggested that “eternal” with respect to God means that God is simply outside the category of time. We could, however, have said that God was “infinite with respect to time” and meant the same thing. The sort of infinity that we are talking about in this chapter, however, is quite different and not to be confused with the meaning of infinity in chapter 7.
What we are talking about now, though, still needs to be clarified by making a distinction between a potential and an actual infinity. A potential infinity was suggested by the use in chapter 7 of the term “everlastingness” and can be easily illustrated by the use of an example: when we were younger we probably, at one point in time, decided to attempt to count to infinity. We began with 1 and went to 2 and then 3, and then just kept going. Of course, we soon tired of trying to count to infinity and stopped, but we can imagine that we could have kept going for, say, an hour, and then passed the task on to someone else, who kept it up for an hour, and then to a third person, and so forth. Now, at no point would any of the people doing the counting actually reach infinity, but we can say that the exercise would never stop, and hence it would be infinite in that sense. We call this sort of infinity that describes a process that never reaches a limit as a potential infinity.
Does a potential infinity ever become an actual infinity, though? There are, to be sure, a great many grains of sand on all the seashores of the earth, but is there an infinity of grains of sand actually existing on these seashores? If we really could count them all, it would amount to a very, very large number, but that number would still definitely be finite. Indeed, it seems that an actual infinity of grains of sand cannot exist, for the earth is limited and an actual infinity is not.
We can imagine an actual infinity, of course, in mathematics; but it seems that such an infinity cannot actually exist, at least in our world. One famous example that shows this is the following: imagine that an actual infinity could exist, so that a library could contain an actual infinity of books with red and black covers. Let us say, though, that we decided to check out from the library all the books with red covers. How many books would be left? It would seem that an infinity of books would be left. In other words, an infinity minus an infinite subset of that infinity would still equal infinity. But, of course, we have absolutely no experience in our world of subtraction actually functioning in that way.
To be clear, then, we have distinguished three sorts of temporal infinities: one sort of infinity would apply to God alone, assuming that God exists. This is the sort of infinity according to which God transcends temporal categories completely. With respect to things subject to time, such as our universe, there are two more types of eternity or infinity—namely, potential and actual.
Now, let us return to the kalaam argument. It is quite clearly logically possible for future time to be potentially infinite, as our little example of endless counting demonstrates. That is, it is quite possible for today to be followed by tomorrow, and for tomorrow to be followed by the next day, and on and on and on. With respect to past time, though, according to the advocates of the kalaam argument, potential infinity is not a suitable category. Why? Because past time has already happened, it cannot be simply “potential” or “possible”. Past time, having occurred, must be actual. But is it possible for an actual infinity of anything such as past time to exist in our universe? According to the advocates of the argument, at least, the answer must be “no”.
But if the only kind of infinity that could apply to past time is an actual infinity, and if actual infinities cannot occur, then the statement “past time is infinite” must be false, which means that the statement “past time is finite” must be true. But if past time must be finite, then it must also have a boundary or a beginning. And hence, the second premise of the argument, the premise that “the universe began to exist”, is demonstrated to be true.
At the beginning of this section, we set the first premise of the kalaam argument aside and studied the second premise instead. This was because the first premise strikes most people as quite obviously in accord with common human experience and, indeed, uncontroversial. We all notice that things that have a beginning “come from” something else and can be said to be “caused” or “conditioned” by those temporally antecedent things. Most people, then, willingly grant the truth of the first premise and accept that “Whatever begins to exist has a cause.” But if the first premise is uncontroversially true and the second premise has been proven to be true, then the conclusion, “the universe has a cause”, would seem to be demonstrated. The advocates of the kalaam argument then conclude that the one doing the causing of the universe would be God, and so God must exist.
B. Objections to the Kalaam Argument
In considering objections to the cosmological argument in chapter 9, we indicated that some people think that the implications of contemporary physics work against the cosmological argument. Some people think that today’s physics also tells against the kalaam argument. The problem, the critics say, is that it is very hard to grasp what time would have been like at the beginning of the universe, if there were such a beginning. As we experience time now, it seems that it could be reasonably represented as a line with arrows indicating that the line extends into the future and into the past, rather like this:
The kalaam argument claims that the line cannot extend infinitely into the past, so it would claim that our “timeline” must be redrawn:
If, however, in an earlier phase of the universe’s existence, time was quite different from what we experience now, perhaps time is not the sort of thing that can be reasonably represented mathematically as a line at all. And if that should be the case, perhaps the advocates of the kalaam argument cannot be too sure that time is the sort of thing that has an edge or a beginning, either. We will examine the relationship between debates about time and the origins of the cosmos further in chapter 16, and we will see that there are many people who think that contemporary physics supports the kalaam argument rather than tells against it. The point to be made just now, however, is that it is not universally accepted that time has always had the qualities that the kalaam argument advocates claim that it has. If it should turn out to be the case that time is not the sort of thing that would make it impossible for an infinity of past time to exist, then the second premise of the argument—claiming that the universe had a beginning—might be in trouble.
A second kind of objection that has been raised against the kalaam argument is the claim that it has misunderstood the properties of infinity. Just as we can easily admit, the detractors of the argument say, that future time may turn out to be a potential infinity, so might past time, for one can always imagine a day before yesterday, and a day before that, and before that, and so on—just as one can imagine tomorrow, and a day after that, and after that, and so on. Indeed, no less a figure than Thomas Aquinas argued that there was no logical reason why past time might not be infinite. In responding to these critics, the kalaam advocates appeal especially to the mono-directionality of time. That is, they argue that “counting back” when it comes to time is different from “counting forward”, for the moments of the past cause the moments of the future, which implies an absolute or initial starting point. They suggest that Thomas and the kalaam critics overlook this point in their analysis. Also, modern kalaam supporters think that their side of the argument has been given a big boost from the mathematical writings of David Hilbert, who seemed to suggest that the discussion of infinite sets with respect to our world is of limited value. They think that Hilbert has shown that an absolute infinity cannot exist and that therefore any attempts to render the notion of an absolute infinity of past time intelligible are doomed to fail.
Thirdly, the first premise of the argument—claiming that whatever begins to exist has a cause—is a premise that has been criticized more than we might anticipate. We indicated in the previous subsection that many people find this premise uncontroversially true, but the premise is actually quite controversial. Why? Clearly, this premise of the kalaam argument assumes the notion of cause. If things begin to exist, the premise asserts, then there must need be a cause for their coming into existence. In treating the cosmological argument, though, we noted that some thinkers want to deny the notion that all events are caused. They want to reject the very principle of ex nihilo nihil fit, or “from nothing, nothing comes.” But if one could make a solid case for rejecting that principle, not only would the cosmological argument be in trouble, but the kalaam argument as well. While the two arguments in no way understand causality identically, they both surely do employ the principle of causality in making their claims. As a result, the sorts of criticisms of the principle of “from nothing, nothing comes” that were treated in the previous chapter are also relevant to thinking about this first premise of the kalaam argument, so readers might want to review them.
C. The Implications of the Kalaam Argument for the Question of Faith and Reason
Again, before going on, it seems valuable to stop and to consider the implications of this argument for our overarching question of the relationship between faith and reason.
Let us say, then, that we decided that the kalaam was sound. What would the argument prove? Well, it would show that at one point in time the universe suddenly began to exist and that its existence was caused by something outside of it. Most theists are pretty sure that we would have to say that this “something outside of the cosmos that caused the cosmos” was God, but so far the argument has not eliminated the possibility of a multiplicity of causes or a group of gods causing the universe. The argument would also prove that the world was created once a long time ago. It would not show, however, that God is continuously present to creation. In other words, the argument would seem to point toward deism just as much as it would point toward theism. Remember, of course, that deism is the view that God created the world once upon a time and then left the world to its own devices. The kalaam argument is consistent either with the claim that the world was created once and then left to itself or with the claim that not only was it created once but that it continues to be created at every instant.
In other words, while the cosmological argument seems to show that the world is created at every moment of its existence, the kalaam argument seems to show only that the world was created at one initial instant. On the other hand, the kalaam argument does claim to show that the world had a temporal beginning, which is something the cosmological does not claim to show.
Let us return yet again to our diagram from chapter 3:
We said at the end of chapter 9 that if the cosmological argument were accepted, then one would have to say that the propositions “God exists” and “God creates the world at every moment of the world’s existence” both belong to region 2 in the diagram—that is, they would be doctrines accepted because they were revealed to faith and because they had been demonstrated by reason. If the kalaam argument were to be accepted, the proposition “The world began to exist” would also belong to region 2, for the opening of Genesis tells us that there was a “beginning” to the world, and now the kalaam argument would offer a rational demonstration of that very event.
Many of our readers may be surprised to learn that Thomas Aquinas accepted the cosmological argument, or at least a form of it, but rejected the kalaam argument. In other words, Thomas did not agree that the proposition “The world had a beginning” belonged to region 2. He did, of course, believe that it was true that the world began to exist, but he believed that on the basis of his faith in the Church, which accepted the revelation of a temporal beginning to the universe as claimed by the Book of Genesis. In other words, Thomas thought the statement “The world had a beginning” belongs, not to region 2, but to region 1. Philosophy, he concluded, could offer us a sound argument that the world was created, but he did not think it could offer us a sound argument that the world had a temporal beginning. Stated still differently, he thought it was logically possible that the world existed from all eternity. In other words, he did not think the proposition “The universe is created and eternal” was inherently contradictory at all. In fact, Thomas agreed with the claim that the world began to exist, but he thought the only way to recognize that claim was by accepting it through faith.
Not every Christian philosopher of the thirteenth century agreed with Thomas; indeed, Bonaventure, another thinker who also eventually received the accolade of “Doctor of the Church”, did accept a version of the kalaam argument. Notice, however, that the argument between the two was not over what was in fact the case about God and the world. Both thinkers agreed that God existed, that God continually creates the universe, and that the universe began to exist in time. The difference was about why they recognized these truths. For philosophers, it is not just enough to agree; one has to agree for the right reason!