That's the question I had after watching Robert Wright interview atheist cosmologist Lawrence Krauss about his new book, A Universe from Nothing. Krauss's thesis is that scientists are now discovering how it is that the universe literally could have come from nothing (as opposed to simply positing that that is what happened, as in earlier accounts of Big Bang theory).
Except it turns out that Krauss's "nothing" doesn't actually mean no "thing." Under his model, even if all the mass and energy of the universe literally came into existence from nothing (a model, as I pointed out before, that is entirely compatible with the Christian doctrine of creatio ex nihilo), our universe would not exist as it does unless its physical laws were already in existence when the Big Bang occurred. In short, Krauss's "nothing" includes the universe's physical laws, which, of course, are things, making his "nothing" something.
When Wright points out that this definition of "nothing" is not what philosophers and theologians have in mind when they say God created the universe out of nothing (starting at the 23:00 mark), Krauss counters that medieval theologians had only a "vague and undefined sense of what nothing is." By this, he evidentally means to suggest that theology needed science to teach it what "nothing" actually means.
But that's nonsense. Granting that people in the Middle Ages knew less about the laws of the universe than we do today, they certainly knew something about them. They knew, for example, that gravity exists. Thus they did not intentionally jump off church towers for the same reason we don't intentionally jump off skyscrapers unless we're trying to commit suicide. Why? Because they knew they'd fall to the ground and probably to their death. I'll go even further and argue that the medieval understanding of gravity was actually quite sophisticated (certainly more sophistocated than the average college graduate's today). Had it not been, then medieval architects could never have invented the flying buttresses that allowed them to build church towers of such great height that jumping off them would have resulted in their death.
So our medieval ancestors clearly knew something about the physical laws of the universe. And when we read medieval theologians such as Thomas Aquinas (b. 1225), it is clear that they believed God was the creator of everything, including the universe's physical laws. As Aquinas explains it in Contra Gentiles, Book II, Ch. 16:
Now, what has been said makes it clear that God brought things into being from no pre-existing subject, as from matter. For, if a thing is an effect produced by God, either something exists before it, or not. If not, our assertion stands, namely, that God produces some effect from nothing preexisting. If something exists before it, however, we must either go on to infinity, which is impossible in natural causes, as Aristotle proves in Metaphysics II, or we must arrive at a first being which presupposes no other. And this being can be none other than God Himself. For we proved in Book I that God is not the matter of any thing; nor, as we have shown, can there be anything other than God which is not made to be by Him.
According to Aquinas, then, there cannot be anything that is not made by God. And this does not simply mean that God created matter itself. It means both that he created its "form" (i.e., its shape and its properties, such whether it exists as a solid or liquid and whether it has a certain color, texture, etc.) and that, as the First Mover, he set it all into "motion" (Ch. 17). And modern scientists, of course, would say that the form and motion of matter cannot be understood apart from the physical laws of the universe, such as gravity, that govern it.
All of which is to say: When Aquinas said God created ex nihilo, he meant exactly that. Why Krauss doesn't know this is surprising since one of his stated goals is to show that science has somehow undermined theological accounts of creation.
So my question is this: How can you undermine a theology that you don't even understand?