Sean Carroll on the nature of science « Why Evolution Is True

I haven’t taken the time to read the whole thing (gotta finish a rabbit hutch) but this part was interesting:
The multiverse isn’t, by itself, a theory; it’s a prediction of a certain class of theories. If the idea were simply “Hey, we don’t know what happens outside our observable universe, so maybe all sorts of crazy things happen,” it would be laughably uninteresting. By scientific standards, it would fall woefully short. But the point is that various theoretical attempts to explain phenomena that we directly observe right in front of us — like gravity, and quantum field theory — lead us to predict that our universe should be one of many, and subsequently suggest that we take that situation seriously when we talk about the “naturalness” of various features of our local environment.
IOW, the idea that our universe is one of many isn’t some wild attempt to get around the Goldilocks idea that certain constants are “just right.” It is the natural conclusion of certain kinds of theories that explain our universe.