fallacy

Tu quoque

Also called: Appeal to hypocrisy, You too

Tu quoque dismisses a criticism by pointing out that the critic is guilty of the same thing. Hypocrisy may say something about the critic, but it does not make the criticism false.

How it works

Turning the accusation back on the accuser changes the subject from the original conduct to the critic's consistency. It is closely related to whataboutism, which redirects to someone else's wrongdoing.

Examples

"You say I should stop smoking, but you smoked for twenty years."

The health risks of smoking are the same whoever points them out.

"Our rivals complain about our emissions, yet their factories pollute too."

The rivals' pollution does not answer whether our emissions are a problem.

How to spot it

The reply is "you do it too" or "look who's talking".
The original criticism is left unanswered.
Attention moves to the critic's past behaviour.

How to respond

Concede the inconsistency if it is real, then return to the original point.
Ask whether the criticism would be valid coming from someone consistent.
Treat both issues separately rather than letting one cancel the other.