House: There's never any proof. Five different doctors come up with five different diagnoses based on the same evidence.
Cuddy: You don't have any evidence. And nobody knows anything, huh? How is it you always think you're right?
House: I don't. I just find it hard to operate on the opposite assumption.
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.