There are two parties, P1 and P2.

There are two behaviors B1 and B2, which both parties agree are ethically undesirable or at least questionable.

P1 consciously refrains from B1, but not from B2, may it be from a lack of awareness, a lack of ability or a lack of integrity. P2 involves in both B1 and B2, also because of a lack of awareness, a lack of ability or a lack of integrity.

P1 argues that refraining from B1 is ethically superior to not doing so, This makes P2 aware of B1 and shows that refraining from B1 is possible. So, now P2 involves in B1 due to a lack of integrity. A lack of integrity is uncomfortable, so P2 tries to justify by arguing that P1 is a hypocrite as she/he refrains from B1, but not B2. Therefore, involving in B1 is ethically equal to not refraining from B1.

Is there a name for this type of pseudo argument? In case it qualifies as a knockout argument, I am still looking for something more specific.


1 Answer 1


This is a tu quoque, or appeal to hypocrisy, a special case of an ad hominem fallacy. The behaviour and moral character of P1 is irrelevant to the truth of the statement "B1 is morally wrong". And if B1 is morally wrong, both P1 and P2 ought to refrain from doing it. Whether one or both does in fact refrain from it changes nothing about the truth of the statement.

A kind-of funny story/example (I can't remember the exact theory being discussed, but it's irrelevant for the example), I had a class where where the instructor was trying to flesh out the implications of some moral theory he believed in. Say one such implication was "one ought to do P". Several students took objection to what the instructor was saying, along the lines of "but you, instructor, don't actually do P!". The instructor joked: "Look, I'm a pathetic failure of a man, so I don't do P. But that doesn't mean that I shouldn't do P, and in fact I do believe that I should do P!". The instructor was, of course, correct that his behavior has nothing to do with the truth of whether one ought to do P or not. Another example might be murderers telling non-murderers that they shouldn't murder (which is, usually I think, true).

  • Thanks. This is a helpful answers, though I am reluctant to accept it as the correct answer, since it is not exactly the thing I am looking for. As I understand tu quoque, P1 would also involve in B1. But I think your answer helps me categorize my case at least as specific as logical fallacy -> argumentum ad hominem. Mar 26, 2019 at 17:49
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    @MarcoEckstein Is there any additional relation between B1 and B2? Or can they be any behaviors that satisfy your original scenario? If B2 can be any behavior, it sounds like what P2 is saying is because P1 engages in any kind of immoral behavior (B2), then P2 doesn't have to be moral (i.e. can do B1 and B2) if the argument to be moral is coming from P1. This would probably just be a regular ad hominem. (Mr. Thief tells me not to murder, but since Mr. Thief steals, I don't have to take his argument that I shouldn't murder seriously.) Am I understanding you correctly? Mar 26, 2019 at 17:58
  • Even though I did not state it, I was thinking of a concrete example where there are reasons R1, R2, ...Rn, one of which (Ri) implies that both B1 and B2 are immoral. Let's assume that P1 argues against B1 (also) because of Ri. Mar 26, 2019 at 18:19
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    @MarcoEckstein I see. I believe in a particular ethics. For this reason, I'm a vegetarian, but I still wear leather shoes, even though my ethical reasons for being a vegetarian probably also imply that I shouldn't wear leather shoes. Is it like that? Mar 26, 2019 at 18:40
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    In this case, I think Conifold's comment to your question is good. Anyways, if my reasons imply that I should be a a vegetarian, and not wear leather shoes, they still imply that I should be a vegetarian. In this case, I could either appeal to Conifold's comment, or simply say it is a moral failing on my part that I still wear leather shoes. This moral failing does not detract from the soundness of arguments I might have. Mar 26, 2019 at 18:41

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