A field guide to the ways reasoning breaks
Attacks on the source
Also called Attack on the person
Rejecting an argument by attacking the character or circumstances of the person making it.
His budget analysis is wrong because he failed math in school.
Restate the argument without naming its author and ask whether it still holds.
From the Latin 'argumentum ad hominem', 'argument to the person'. Named by philosophers to mark a rebuttal that answers the speaker rather than the speaking. It is as old as rhetoric itself.
Don't take her climate research seriously — she used to work in the oil industry.
Of course he supports the new tax code; he stands to profit from it, so his analysis must be wrong.
You can't trust his essay on food policy; I've heard he's a slob in person.
Her solution to the committee gridlock may be sound, but let's not forget she hasn't chaired anything yet.