I have to look it up as well. I haven't read the whole of the five ways in ages. The simplest error is to take 'proof' as meaning 'demonstration' when it merely means 'test'. Aquinas is only trying to show that belief in a deity is reasonable, not conclusive.
Ed Yetman, III
"I will not be pushed, passed, isolated, blockaded, doubled, undoubled, or promoted!"--The Pawn.