"Empirical reasoning does not operate in absolutes."
Precisely, and so 'rule out' shouldn't be taken to imply an absolute ruling out of things. =)
Perhaps I should've said effectively ruled out. Life on the Moon has been 'effectively' ruled out (lack of liquid water, no atmosphere, full exposure to radiation and impactors, etc.) - but many years ago it wasn't extremely unreasonable to suppose that life might exist there. Now we know better - we'd have to reach for very convoluted scenarios to argue for the existence of life on the Moon. The same is not true for Mars (although it's not a picnic, obviously), which I would say is remarkable - there aren't many celestial bodies that have passed that test.
Precisely, and so 'rule out' shouldn't be taken to imply an absolute ruling out of things. =)
Perhaps I should've said effectively ruled out. Life on the Moon has been 'effectively' ruled out (lack of liquid water, no atmosphere, full exposure to radiation and impactors, etc.) - but many years ago it wasn't extremely unreasonable to suppose that life might exist there. Now we know better - we'd have to reach for very convoluted scenarios to argue for the existence of life on the Moon. The same is not true for Mars (although it's not a picnic, obviously), which I would say is remarkable - there aren't many celestial bodies that have passed that test.