A: all crows are black
B: It is not evident that all crows are black .
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.
B: It should be obvious to anyone with half a brain that calling people names is unacceptable .
MoonShadow/FlameWar