Hume makes some very important challenges to the Cosmological argument which some believe count decisively against it. One of the key areas he calls into question is the argument’s dependence upon what Leibniz termed the principle of sufficient reason. In this principle an adequate explanation must be a total explanation. The universe requires an explanation of itself as a whole. But many would say, as Russell later told Copleston: “Then I can only say that you’re looking for something which can’t be got, and which one ought not to expect to get.” If you have explained each individual element of a series any explanation of the series as a whole would seem to be superfluous, and besides he says that ‘the whole’ doesn’t really exist anyway – it is ‘an arbitrary act of mind’ that makes things into wholes. What we term the ‘whole universe’ in modern physics may be only a bubble in a larger reality that we have no way of grasping. Also if we are only entitled to talk about causes when we have had experience of them, then this argument would seem to be over-stretching itself in speculating upon what it cannot know. On the other hand, there is of course a problem with stopping at a certain point and saying that we should seek no further explanation, in that it is a basic presupposition of all scientific work. However, even though a principle of rationality is that we can find an explanation for things, it is not a logical requirement – there is no guarantee that there will be one. So, I think Hume significantly weakens forms of the argument that depend on the principle of sufficient reason. However, I think that Hume’s criticisms of a necessary being somewhat misunderstand what is meant by necessity in this case. Some have said that this argument arrives at a factually necessary being, not a logically necessary one, so that Hume’s point that any being may or may not exist is question-begging because the argument seems to arrive a posteriori at a being that has to exist. Hume has outlined some powerful problems with the argument, but they do not totally defeat it. I think we are at least entitled to ask the question of what caused the universe, as this is what modern physics does. The difficulty is in arriving at the Christian God as an answer to such a question. I think therefore that Hume was fairly but not completely successful in his criticisms of the argument.
