Modern advocates of the argument, such as philosophers Stephen Davis and William Lane Craig, outline the argument somewhat like this:
- Any entity that exists must have an explanation for its existence, either in itself or in something else.
- The universe exists.
- Therefore, the universe has an explanation for its existence, either in itself or in something else (from 1 & 2).
- If the universe has an explanation, that explanation is God.
- Therefore, God exists (from 3 & 4).
Premise 2 is obviously true, but what about 1 and 4? In the remainder of this post we'll look at premise 1 and then consider premise 4 tomorrow.
What does premise 1 mean? It's simply an expression of what's called the Principle of Sufficient Reason. Existing entities have an explanation of their existence either in the necessity of their own nature or in some external cause.
To say that their explanation is in the necessity of their own nature is to say that it's impossible for the thing to not exist. It's not caused by anything else nor is its existence in any way dependent upon anything else. It has what philosophers call necessary being. Some mathematicians think that numbers and other mathematical "objects" exist in this way.
Almost everything in our experience, however, is explained by some cause outside of itself. These things - like trees, chairs, cars, and people - could possibly not exist and are referred to as contingent beings. They depend upon something outside of themselves for their existence.
So premise 1 is saying that every entity which exists is either a necessary being or a contingent being. This is clearly the case, so the universe, which is of course an existing entity, is either a necessary being or a contingent being. It's possible, however, that the universe not exist. Indeed, there was a state of affairs, apart from the Big Bang, in which it did not exist. Therefore, the universe is contingent, and its explanation must be found outside of itself.
Now, there's much more that could be said about premise 1. There are objections that have been raised, and answered, to the claim that the universe is contingent, but I think it fair to say here that the contingency of the universe is by far the consensus view among philosophers who attend to the matter. It's difficult to imagine that the universe is necessary, i.e. the sort of thing that could not not exist.
Thus we're left to defend premise 4 which certainly seems to commit the fallacy of begging the question. That is, it seems to be stating the very thing the argument strives to conclude. As we'll see the next time, though, so far from begging the question, premise 4 simply affirms what most atheists say all the time.