Another view, advanced by Richard Dawkins, is that the existence of God is an empirical question, on the grounds that "a universe with a god would be a completely different kind of universe from one without, and it would be a scientific difference." Carl Sagan argued that the doctrine of a Creator of the Universe was difficult to prove or disprove and that the only conceivable scientific discovery that could disprove the existence of a Creator would be the discovery that the universe is infinitely old.