Tuesday, February 09, 2016

Are tu quoque arguments fallacious?

Some pop internet sources classify the tu quoque argument as a fallacy, but that's erroneous:

I am using ad hominem in the way Peter Geach uses it on pp. 26-27 of his Reason and Argument (Basil Blackwell 1976):
This Latin term indicates that these are arguments addressed to a particular man -- in fact, the other fellow you are disputing with. You start from something he believes as a premise, and infer a conclusion he won't admit to be true. If you have not been cheating in your reasoning, you will have shown that your opponent's present body of beliefs is inconsistent and it's up to him to modify it somewhere.
As Geach points out, there is nothing fallacious about such an argumentative  procedure. If A succeeds in showing B that his doxastic system harbors a contradiction, then not everything that B believes can be true.  


  1. I'm glad someone is standing up for tu quoque arguments. I see a lot of Catholic and EO apologists making the charge of fallacy when they get pressed with a tu quoque argument. But what it really does is expose a false premise in their objection.

    Have you expanded on this elsewhere? Or has someone else come out in defense of tu quoque arguments that is worth reading?

  2. To me, a tu quote argument is an argument from (or by) analogy.

    Suppose someone says: "You should vote for Hillary because she's a woman. That would make history. That would advance the cause of women."

    Suppose I respond: "In that event, you should vote for Rubio because he's Latino. That would make history. That would advance the cause of Latino minorities."

    That's a tu quote argument. And it's an argument from analogy. But it's hard to see how that's fallacious. You're responding to the person on their own grounds by creating a parallel argument.

    It's a way of forcing them to be consistent. If they invoke a general principle to justify a particular action, you invoke the same principle (for the sake of argument), to justify a related action–which is contrary to their position.

    That puts pressure on them to relieve their inconsistency by surrendering the principle, if they can't apply their principle consistency.

    We could also view it as a reductio ad absurdum of their position. We take their premise to a logical extreme, which has unacceptable consequences for their overall position.

    Now, in the aforesaid case, I might not support Rubio for president. Maybe I prefer Cruz or Jindal or Rand Paul. But that's irrelevant to the force of the argument, since I'm arguing from assumptions provided by my opponent.