A: the moon is flat
B: I dispute your premise.
A: You're quite wrong, all crows are stripy
B: I dispute your premise.
A: You're quite wrong, all llamas are stripy
B: It is not evident that all llamas are stripy .
A: Since you disagree with me, I can only assume you don't know enough about the subject. Go read a book, and don't talk about the subject any more until you agree with my views on it.
MoonShadow/FlameWar