Can two wrongs make a right, or can two wrongs not make a right? If John Hammer and John Stewart both did wrong, does it make both instances OK?

Two wrongs make a right is a logical fallacy that occurs when it is assumed
that if one wrong is committed, another wrong will cancel it out.


Like many fallacies, it typically appears as the hidden major premise in an enthymeme
—an unstated assumption which must be true for the premises to lead to the conclusion.

This is an example of an informal fallacy:

Speaker A: You shouldn't embezzle from your employer. It's against the law.

Speaker B: My employer cheats on their taxes. That's against the law, too!

The unstated premise is that breaking the law (the wrong) is justified,
as long as the other party also does so.


It is often used as a red herring, or an attempt to change or distract from the issue.

For example:

Speaker A: President Williams lied in his testimony to Congress. He should not do that.

Speaker B: But you are ignoring the fact that President Roberts lied in his Congressional testimony!

Even if President Roberts lied in his Congressional testimony,
that does not make it acceptable for President Williams to do so as well.
(At best, it means Williams is no worse than Roberts.)


By invoking the fallacy, the contested issue of "lying" is ignored.

The tu quoque fallacy is a specific type of "two wrongs make a right".

Accusing another person of not practicing what they preach,

while appropriate in some situations, does not in itself invalidate an action

or statement that is perceived as contradictory.

Two wrongs don't make a right


Two wrongs don't make a right is the proverb that contradicts this logical fallacy.


It means that a wrongful action is not a morally appropriate way
to correct or cancel a previous wrongful action.


Wiki

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The fallacy is commonly used to justify actions,

perhaps most noticeably in conflicts between countries and ethnic groups.

Palestinians and Jews alike can point to perceived injustices committed by the other side,

in some cases stretching in to the distant past.

This same pattern can be seen in arguments over The Crusades

in which Muslims and Christians attempt to attribute blame

by citing slights committed by the other side.

Eddie Murphy provided an example of this during a comedy stand-up performance

when he told a joke about wandering up to a white man and saying

"I just lost my job today, to a white man, looks just like you!"

He went on to explain that he was going to beat up some white guys to redeem himself.

Color may or may not be relevant,

but assuming that the loss of his job was wrong,

it is certainly the two wrongs make a right fallacy being committed,

since there's no other justification provided for the threatened assault.