Craig’s second argument in Reasonable Faith, is probably the one he’s most famous for, the Kalam cosmological argument. He begins by arguing:
- Whatever begins to exist has a cause.
- The universe began to exist.
- Therefore, the universe has a cause.
Obviously, Craig needs further arguments that if the universe has a cause, the cause must be God. He never does more than briefly sketch those arguments, which should be a red flag, since without those arguments the rest doesn’t amount to much. But hold off on that until later.
Craig claims premise (1) is obviously true. Many people don’t think it is, including myself and philosopher of religion Keith Parsons, but I don’t think this is anywhere close to being the worst problem with Craig’s argument, nor do I see much point in arguing over what’s obvious, so I’d be happy to grant Craig (1) for the sake of argument.
I really want to focus on (2). Craig gives two types of arguments for (2), scientific arguments and philosophical arguments. I’ll deal with the scientific arguments first.
One argument Craig uses appeals to the second law of thermodynamics. The second law of thermodynamics says that the entropy in a closed system will steadily increase until it’s at its maximum (or, put another way, that a closed system will tend towards equilibrium). Because the universe’s entropy isn’t at its maximum, isn’t in a state of equilibrium (which is good for us, or else life would be impossible), the universe can’t be infinitely old.
Here’s one problem with using this as an argument for God: what if there’s an undiscovered exception to the laws of thermodynamics? Craig can reply that there’s no evidence that such an exception exists, and that the laws of thermodynamics have always been found to hold throughout countless observations. But Craig’s own view involves postulating a massive exception to the laws of thermodynamics—namely God.
In other words, Craig’s strategy requires first dismissing the possibility of some physical exception to the laws of physics based on lack of evidence, and then arguing to God. But it would make just as much sense to first dismiss the possibility of God based on lack of evidence, and then argue to a physical exception to the laws of thermodynamics.
The Big Bang theory describes how, over the last 13.5 billion years, the universe expanded from something that was originally very small into the unimaginably large universe we have today. It is often assumed this means the universe began 13.5 billion years ago, but to many scientists, the idea that the Big Bang theory is a theory of how the universe began (as opposed to how it developed) is a misconception.
Craig spends a lot of time trying to shoot down theories which, while consistent with what the Big Bang says about the expansion of the universe over billions of years, do not say that the universe began to exist. The problem with this is similar to the problem with trying to use the laws of thermodynamics to prove God.
While it may be hard to say exactly what makes something “science” or “good science,” it’s safe to say that when scientists frame their theories, they’re at least supposed to be constrained by the evidence. When Craig tries to shoot down particular scientific theories about the history of the universe in Reasonable Faith, he’s attacking theories framed under that constraint.
However, if you don’t care about the standards normally applied to scientific theories, it’s ridiculously easy to come up with a story about how the past could be infinite. After all, maybe God decided to make it look finite in spite of being infinite. So Craig needs those normal standards.
His God hypothesis, however, doesn’t meet them. As with the thermodynamics argument, there’s no evidence for it except that (allegedly) we’re forced to it once the alternatives have been ruled out. And in the Kalam argument, Craig keeps his God too vague to test against the evidence.
Craig may protest that “God is a better hypothesis than the alternatives” is not a claim he makes at any step in his argument. True. However, the fact that Craig never explicitly makes this claim is no excuse for rejecting other people’s views using one set of standards, and then refusing to apply those same standards to his own beliefs.