Last week, we began a survey of red herrings, responses to an original argument that don’t address the original issue, with argumentum ad hominem, discrediting an argument by attacking the arguer.
Ad hominem tu quoque
Tu quoque (“you, too”) is a subset of ad hominem in which the character flaw used to discredit the arguer is that the arguer has been inconsistent or hypocritical on the same subject in the past. There are several subsets:
Person A criticizes behavior B.
Person A has been guilty of behavior B.
Therefore, person A’s opinion is invalid.
Although Person A has been a hypocrite, that doesn’t mean A is necessarily wrong. As François de La Rochefoucauld famously observed, “Hypocrisie est un hommage que la vice rend à la vertu.” (“Hypocrisy is the tribute vice pays to virtue”) A person can indeed be guilty of behavior and legitimately deplore it at the same time. In my own case, it’s fair to say:
Michael complains about ad hominem attacks.
Michael has committed ad hominem attacks in the past.
Therefore, Michael’s complaint about ad hominem is invalid.
It’s fallacious because our individual hypocrisies and failures of consistency don’t prove we’re wrong; sometimes they can even be evidence that our propositional ideal is more correct. Ad hominem attacks are a bad idea, whether or not I have been consistently able to refrain from them — in fact, the fallout from my own violations has tended to reinforce my belief that it’s a bad idea.
Another version of tu quoque is claiming inconsistency. In this version, the form is:
Person A makes claim C.
Person A has previously made claims that are inconsistent with C.
Therefore, claim C is false.
In 2008, Bill Gates said, “People everywhere love Windows.” In 1987, however, Bill Gates said, “I believe OS/2 is destined to be the most important operating system, and possibly program, of all time.” Although the first statement is arguable (he said as he types on his Macintosh), offering the second statement as a rebuttal to the first is a logical fallacy.
There are two legitimate uses of tu quoque arguments. The first is legal, the maxim that you cannot approach the courts of equity with unclean hands. If you fail to live up to your obligations under a contract, you may not be able to prosecute a claim that the other side has also failed, as long as their failure to perform is linked to your failure.
The other legitimate use of tu quoque is to discredit someone as a role model for a position. If Person A has built a political career on being a faithful marriage partner but turns out to be actively polyamorous, it’s perfectly legitimate to argue that Person A is no longer credible on the subject. That’s different from arguing that Person A’s infidelity proves that faithfulness in marriage is not a good idea.
The expression “pot calling the kettle black” can also describe some forms of tu quoque arguments. Another famous example can be in the punchline to the famous 1960s era Russian joke, “А у вас негров линчуют.” It goes like this. An American and a Soviet car salesman are arguing about which country makes better cars. The American asks, “How many decades does it take an average Soviet man to make enough money to buy a Soviet car?” The Soviet answer? “And you are lynching Negroes!”