A: all crows are black
B: I don't know of a better way to put it: you're wrong.
A: You're wrong.
B: It is clearly not true that all crows are black .
A: You're wrong.
B: It is not evident that all crows are black .
A: The evidence clearly shows that all crows are black .
B: You're quite wrong, the earth is flat
A: Isn't that a non sequitur?
B: the earth is self-evidently not flat .
A: The evidence clearly shows that the earth is flat .
B: It is clearly not true that the earth is flat .
A: Sir, you are a buffoon.
B: It should be obvious to anyone with half a brain that calling people names is unacceptable .
MoonShadow/FlameWar