What are the Odds of Extraterrestrial Life?

INTERVIEWER: Do you believe in the existence of extraterrestrial life, and if so, what would you say is the greatest proof for it?

DR. CRAIG: Well, I don't believe in it, but on the other hand I don't disbelieve it either. I would take a position of just non-belief. I don't know whether there is extraterrestrial life. I know that evolutionary biologists do say that the evolution of intelligent life comparable to that on Earth is so enormously improbable that it's unlikely to exist anywhere else in the observable cosmos. We are likely alone in terms of intelligent life. Now that doesn't exclude there can be slime molds, or something on other planets elsewhere in the universe, but in the universe as we know it, it seems to be a consensus among evolutionary biologists that the evolution of carbon-based life capable of the information processing that we're able to do is just so improbable it wouldn't have arisen twice.