Is there anything wrong with that logic? After all, we experience this process every day. I get into the bus, get to the college, and attend a lecture on the Cosmological Argument. If I had not got into the bus and stayed in bed instead, then there would have been no drive in the bus and no lecture. My difficult decision to get out of a warm bed and stumble into a cold car was undoubtedly the cause of my getting to the college to attend a lecture. However, getting into the bus was not the cause of everything else in the whole universe! It is not, therefore, the First Cause. If 'A' is the first cause, then 'B' must also be the first cause of 'C', and 'C' the first cause of 'D', and so on. Every cause would be the first cause! We are also faced with the obvious paradox here of, on the one hand, saying that everything has a cause and, on the other, saying that there is a cause of itself; something that was not caused by something else!
Aquinas rephrased the argument in terms of dependency: Doesn't dependency have to be grounded somewhere in non-dependency? Every creature is dependent (i.e. contingent) for its existence on something else, without which it would not have been. For example, if my mother had not met my father during World War Two then I would not now exist. In fact, I also have the war to thank for my existence today. But how can you have a chain of dependent beings without, at the end of the line, having a being that does not depend on something else? There must exist a non-dependent, self-existent, necessary being. The very fact that one being depends upon another being suggests that dependence must come to an end at some point; or can you have infinite dependency?
This argument is still causal, but plays on the term 'dependence' rather than 'cause'. However, as Bertrand Russell once pointed out, just because every human being had a mother it does not follow that the human race as a whole had a mother. In other words, it is wrong to argue from individual cases to a whole collective. Three people can have their own individual reasons for, say, going to see the same film, but it does not follow that there need be one collective reason why the group of three are in the cinema at the same time and sitting next to each other. We could also follow the path of David Hume who would argue that, as the creation of the universe is beyond our experience, there is simply no empirical evidence to satisfy our curiosity. John Stuart Mill ( in his article Theism, said: 'Our experience, instead of furnishing an argument for a first cause, is repugnant to it.'
Still, we can't help being curious. Nonetheless, Hume and Mill have a point: where does all this speculation leave us? Does it help us to believe in a First Cause or, for that matter, in the existence of God? A religious believer may well be able to say that God is 'special': to ask the question "What or who caused God?" misses the point entirely and is, in fact, irrelevant here. God just is: he is the eternal, uncaused, timeless, creator.
Equally, the atheist could use a similar argument in response to the question: "What caused the universe?" As Russell once said: "I should say that the universe is just there, and that is all." The universe just is: like the laws of nature, the universe is a brute fact; it's the way things are. Neither response is particularly helpful, it has to be said.