Thomas Nagel on the Cosmological Argument"Why Is There Anything?" in Secular Philosophy and the Religious Temperament (Oxford University Press: 2009), P. 28.
The existence of our universe might be explained by scientific cosmology, but such an explanation would still have to refer to features of some larger reality that contained or gave rise to it. A scientific explanation of the Big Bang would not be an explanation of why there was something rather than nothing, because it would have to refer to something from which that event arose. This something, or anything else cited in a further scientific explanation of it, would then have to be included in the universe whose existence we are looking for an explanation of when we ask why there is anything at all. This is a question that remains after all possible scientific questions have been answered.