Recently, a colleague of mine felt stung by something I said in an argument. He complained that I was making an “ad hominem” argument. I want to clarify this issue, because it’s a common mistake: what I was making was a personal attack, not an ad hominem argument.
A personal attack is when someone criticizes you as a person. They may argue that you are a bad person, and that you ought to mend your ways. Their argument may be logically valid. For instance, consider this statement: “I think you are behaving unethically by stating or implying, in your advertising literature, that ISTQB certification represents an industry-wide consensus about what excellent testing is or should be, when there is widely documented controversy over this among serious, experienced, and respected thinkers in the field. In fact, you have personally experienced and acknowledged that controversy over a period of years, in conversations with, among other people, me, and I have the email records to prove it.”
The argument here is that it is unethical to make a claim that one knows to be false, or that can easily be taken to mean something that it doesn’t mean. This is a general argument. I could be more specific and argue that it violates clauses 3, 6, 7, and 9 of the IEEE Code of Ethics, but specificity can vary in a natural language argument without committing fallacy.
This may or may not be a compelling argument. There may be a valid counterargument. But this argument has a valid logical form. To utter this statement would be a personal attack, I think, because it is a complaint about personal behavior. But it would not be an ad hominem attack.
A personal attack is not a good idea if you want to maintain a high quality personal relationship, but that’s a whole other issue. I hate burning my bridges with people, but sometimes I don’t see any other option that preserves integrity.
An ad hominem argument is a fallacy of reasoning whereby someone justifies a criticism of your idea by arguing that you are a bad person. It’s a variation of the non sequitor argument (e.g. “The sky is blue because I like pie.”)
An example of an ad hominem attack is “Mr. Attila the Hun, I realize that you think you have at long last proven Goldbach’s conjecture– that any even number greater than two can be expressed as the sum of two prime numbers– but I’m sure you must be wrong, since you are, after all, just a murderous Hun. Now go! And take that Horde with you.”
See the difference?
The rhetorical effect of claiming that an argument is ad hominem is to release the claimant from having to answer the personal attack. It’s a common tactic, but that tactic may itself be logically invalid. The retort “Your argument is ad hominem because it is directed against me as a person” is a non sequitor.
I wish I never had to be in the position of speaking out against what looks to me like bad behavior. I wish I never had occasion to make an attack against a person. Perhaps someday I’ll give up and let other people stand up for what seems right. For now, I don’t see an acceptable alternative. Someone, somewhere, someday, is going to be killed by software that is tested by well-meaning people who got negligent advice about how to test. I feel like I should do something.
As always, I ask my friends and enemies alike to help me identify and correct any of my own bad behavior. Communities must police themselves. Hence, I accept the IEEE Code of Ethics.