Definition
Tu Quoque
Tu quoque is an informal fallacy that dismisses a criticism by accusing the critic of the same behaviour or holding the same position.
The Latin phrase means “you too”.
Why it Fails
Whether the critic is guilty of the same conduct has no bearing on the validity of the criticism itself. An argument must be evaluated on its own merits. Hypocrisy may undermine the critic’s credibility, but it does not refute the claim being made.
Relation to Ad Hominem
Tu quoque is a form of ad hominem. Instead of attacking the speaker’s character directly, it attacks the speaker’s consistency. The focus remains on the person rather than the argument.
Example
Example
“You cannot tell me to stop smoking; you smoked for twenty years.”
The speaker’s past smoking habit does not invalidate the health argument against smoking. The claim stands independently of who makes it.