Ad hominem

I just read this good point in passing on Bad Astronomy and felt like adding my own additional commentary to the concept of the ad hominem fallacy.

A lot of people think that using an ad hominem — an argument that attacks the person and not the issue –is a logical fallacy. That’s not necessarily the case. For example, if someone on the street walks up to me and say, “Aliens speaking with the voice of Glenn Beck are sitting on my shoulders and forcing me to eat brussel sprouts, and Obama’s health care plan will set up death panels,” then there is some merit in questioning the person’s sanity before wondering if what they say about the health care plan is true.

A person can be crazy and right, crazy and wrong, or crazy and partially right/wrong. If they are wrong, it’s because what they are saying is false. They aren’t wrong because they are crazy. They might be saying wrong things because they are crazy, but they aren’t wrong because of it. They’re wrong because the facts simply don’t agree with their statements.

So when I say someone is a stupid hypocritical affectionless bitch, I say that because I’m insulting her and her argument is wrong. So that is not an ad hominem fallacy (an “attack”, yes, but not a fallacy). If I said she’s a stupid hypocritical affectionless bitch therefore she is wrong, then I would be committing an ad hominem fallacy. Being stupid/crazy does provide context though, like Phil said. It doesn’t make them wrong automatically, but it gives you an idea of whether or not you’ll have to spend some time on Google later feeling superior. For example, the links there are for PETA and the Illinois Family Institute – the known crazy of these organizations provides context for what they’re “arguing”.

I only bring this up because people on blogs and forums often confuse this logical fallacy with people just being dicks. If someone calls you a moron and then proceeds to factually dismember your argument, that is NOT an ad hominem fallacy. It’s just being a dick. If they are trying to discredit what you are saying on the sole basis of past situations where you may not have come off that well, that is “poisoning the well” which is a kind of ad hominem fallacy. Or “don’t listen to this guy, he’s an idiot” with no presentation of an argument whatsoever – that is an ad hominem fallacy. Etc.

[The More You Know music]


2 responses to “Ad hominem

  1. “The more you know” music… hee!

    Thank you for this. I sort of kind of knew it but having it laid out makes it so much better in terms of understanding it.

    I think that the next thing though is that smart people can be wrong too… (your Penn and Teller pie post springs to mind). When I was a kid I thought my dad was super smart and always right. Now I know… he is very smart, but often wrong.

    • Ah yes, the infamous argument from authority. So-called TrueSkeptic (over at Skepchick a while back) was a fan of that one — “I went to this or that college and know so-and-so and have X degree, etc.” Similarly, while this provides context for what the person is saying, it’s not a good enough reason to take them at their word. As always, the evidence is what matters. Smart people can most definitely be dumb.