Faulty logic: Argument ad hominem

We’ll resume normal blogging after the Japanese break with the next in the series on logical fallacies. It’s time for...

Arguing ad hominem

From Latin for “to the man”, an ad hominem argument is one that attacks the speaker, rather than the issues. We all know this one; we see it all the time. We likely use it all the time ourselves, even though we try not to. “Oh, don’t listen to him; he’s a {kook | liberal | wing-nut | Nazi | moron | ...}.” C’mon: tell you’ve never said anything like that.

In a way, arguing ad hominem is the opposite of appeal to authority. In that, we’re asking the listener to accept someone’s argument because she’s especially deserving of attention. In this, we’re asking the listener to reject someone’s argument because she’s not worth our attention — but in both cases, we’re not addressing the content of the argument.

Colloquially, we’ve taken to generalizing the sense of ad hominem, pulling it out any time someone says something bad about her opponent. From the point of view of reasoned argument, though, we only hit the faulty logic when we use a personal aspect instead of addressing the substance of the arguments being made. I might or might not be bothered to have my interlocutor call me a crazy bastard, but questions about my sanity or parentage are irrelevant to whether or not I’m right.

Impolite, but logically sound: “He’s a crazy bastard! He’s wrong for the following reasons: (1) [...etc...]”

Impolite, and unsound, employing argument ad hominem: “He’s a crazy bastard! I don’t know why anyone bothers listening to him.”

Now, this fallacy brings us to a sticky point: if we say that ad hominem arguments are never valid, we’re pretty much saying that everyone is worth listening to and arguing with. If we can’t dismiss some people as “crazy bastards”, we leave ourselves open to denial-of-service attacks, having to fend off one opponent after another, each of whom should have been dismissed summarily, as Barney Frank did in August:

On what planet do you spend most of your time?

[...]

Ma’am, trying to have a conversation with you would be like trying to argue with a dining room table. I have no interest in doing it.

Ad hominem for sure, but... I agree with him, and I love the way he did that. What to do?

Sticking to the argument helps. It might seem that there’s little difference between “You’re an idiot, and you’re not worth responding to,” and “Your argument is so idiotic that it isn’t worth responding to,” but there really is quite a significant difference between them. But it’s still best to refute the arguments when you can.