- Everything that begins to exist has a cause.
- The universe began to exist.
- Therefore, the universe has a cause.
This argument sounds so smooth and plausble, unless you've ever taught physics at the undergraduate level or below. It turns out that whenever one applies everyday intuitions to the universe as a whole, you get pretty much everything wrong, and so it is in this case.
Think about what you really mean by "everything that begins to exist has a cause." Consider a rock, a tree, or the internet. The rock formed when molten magma cooled and hardened, and then broke up into little pieces over time. The tree grew up from an acorn by taking in vast amounts of energy and nutrients over many years. The internet was formed over decades by the dedicated labor of thousands of scientists, technicians, engineers, programmers, and the like. All of these things began to exist because of the rearrangement of preexistent matter and energy into new forms within space over a period of time. The causes which brought these new things into being are those particular events and processes that contributed to their formation, working their effects within space and time according to natural law.
Nowhere else in the English language do we ever use the word "cause" to mean anything remotely akin to "an immaterial entity acting outside of space/time to produce new matter/energy out of nothing" and as a sophisticated professor of philosophy, Dr. Craig surely knows this. Yet, he sees fit to slide this slippery equivocation into his leading argument for the existence of a god, and never bothers to mention the difficulties inherent in doing so. Presumably, he is waiting for his opponent to raise the issue on rebuttal, although (oddly enough) that almost never happens.
This is not logical deduction, this is smooth-talking equivocation of the highest order, the sort that should make even Bill Clinton or Bill Kristol blush. Freethinkers who encounter this argument from theistic apologists would do well to point this out.