For a refresher, the Kalam cosmological argument (KCA) is as follows:
- Whatever begins to exist had a cause.
- The universe began to exist.
- Therefore, the universe had a cause.
Now most people do not deny (2) (although it is the case that assuredly many do). Instead they opt to deny (1). A particular way of doing so is to posit the multiverse. They reason, “Since the causal principle is based on induction of what we have seen in our universe, perhaps it is the case that there is a multiverse. Whether the causal principle holds in the multiverse, then, cannot be told--for we have not seen any other part of it than our own. Hence, we cannot claim the causal principle as true.” Now, aside from the fact that, all too often, this kind of move is done as a desperate ploy to avoid a First Cause as much as anything else, we may say something else about it.
The main criticism I have is that it is simply not true that the causal principle is based on induction. It is certainly confirmed by our inductive experiences, but there are arguments to be had from the KCA supporting it. Namely, if the causal principle is false, then it remains unclear what, precisely, prevents just anything from popping into existence uncaused. In order to overcome the causal principle, then, someone must deal with this argument.
It is sometimes counter-argued that this line of reasoning is a mistake; it need not be the case, they say, that if the causal principle in the KCA is false, just anything could pop into existence uncaused. The causal principle could still hold for the overwhelming majority of things. But this too is a mistake. For the argument is not, “if the causal principle is false, then everything can pop into existence uncaused.” Rather, the argument is, “if the causal principle is false, it’s unclear what prevents things from popping into being uncaused.” The distinction is crucial. We cannot claim it is some physical law, for that law, as a descriptor of the function of the universe, will describe some process of causation, which is ex hypothesi not what we want. We know, after all, that birds come from eggs that are hatched, and that this is governed by physical processes. But why is it that a bird cannot just appear in my bedroom, uncaused? It would not be a normal bird, sure, but that certainly does not matter. We cannot offer some metaphysical truth, for then we have simply stated some other version of the causal principle (or, worse, an ad hoc version like “everything but the universe comes into existence by a cause”).
Now, if this argument that supports the causal principle stands (or any such argument), which I think it does, then the objector who claims the multiverse as backup simply is barking up the wrong tree. The multiverse will not avoid a causal principle unless good reason to reject the causal principle is presented on metaphysical grounds. However, in that case, it will be just such a metaphysical argument that is at work, and not the multiverse.