Let's also stipulate (this happens to be true) that Isaac Newton had bouts of "crazy" behavior later in life — probably due to his incautious handling of mercury during his experiments.
If we thus conclude Isaac Newton was a "kook," does this make it safe to step off the balcony of a high-rise building, confident that Newton's characterization of the laws of gravity don't accurately predict our subsequent tumble to our deaths?
No. The theory of gravity stands or falls based on how it explains observable phenomena in the real world, not on whether we approve of Isaac Newton's style of dress, whether he used the correct fork at dinner, or whether he occasionally crawled around on all fours chattering like a badger.
—Vin Suprynowicz, Tortoise breeding endangers Fish & Wildlife jobs
Jerry: You do know I'm right!
Jerry: You've resorted to abuse.
Tom: ...Shut up!
"When you have no basis for an argument, abuse the plaintiff."
"The thing I love about this is, on the internet, people make a big deal out of the distinction between calling someone names as a way of refuting their arguments, and calling someone names just as a kind of a hobby."
"Sure, he's an asshole. Sure he's dead. Sure, I'm just imagining that he's talking. That doesn't stop the bastard from being absolutely right."
— Dwight, Sin City: The Big Fat Kill
"Ad hominem is a notoriously weak logical argument. And is usually used to distract the focus of a discussion - to move it from an indefensible point and to attack the opponent."
— Lord Aquitainus Attis, Furies of Calderon