Ad hominem, for lack of a better word, is good
The logical fallacy is rational triage
Like how begging the question no longer colloquially refers to the fallacy of reasoning it once did, the definition of ad hominem seems to have expanded to include any criticism whatsoever — even useful criticism that points to sources of bias or conflicts of interest. It’s true that while argumentum ad hominem is not a valid argument in formal logic, it is a valid argument in science, politics, and general rational discourse. That’s because these arguments have a separate properties aside from being formally logical — they can be useful.
Formal logic is a severely restricted subset of the methods for drawing conclusions about this world that leaves out issues of empirical evidence, human nature, or limited bandwidth. In science, we rely on Hume’s “uniformity of nature” a lot. You can’t prove in formal logic that the sun will come up tomorrow based on a series of observations that it has come up in the past. It’s not a logical argument, but it is a useful one.
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An ad hominem argument is a kind of “uniformity of human nature” argument. Sure, it’s not formal logic — but information about people who were biased, used motivated reasoning, or cherry-picked evidence in the past is extremely relevant to dismissing their latest foray.
If Prof. X has published a string of 10 papers that are discovered to be in error and retracted, it is ad hominem to use this fact to discount the 11th paper. But science as an institution would do it — possibly waiting until someone else publishes a paper on the same subject before engaging with it again. Everyone sees papers from think tanks in economics that make zero effort to show how they mitigate bias towards the interests of their wealthy donors, nor explain why they always seem to come up with negative effects of raising the minimum wage. It’s ad hominem, but it’s valid.
Richard Feynman's entire “Cargo Cult Science” commencement address could be considered an ad hominem argument against bad science. For example, we can safely ignore the claims of “scientists” who fail to ‘lean over backwards’ to counter their bias towards their own ideas. The speech is entirely about how you should conduct yourself so you aren’t subject to ad hominem dismissal — which he is entirely in favor of if you haven’t done the work. And while I’d agree that an unsupported ad hominem argument isn’t particularly useful (“u r dum lol”), a blanket dismissal of ad hominem arguments renders the discourse vulnerable to known fabulists and corporate tools.
So in the same way the uniformity of nature is useful, despite not being formal logic, argumentum ad hominem (the uniformity of human nature) can be equally useful if properly deployed.
The thing is — we use it all the time with credentials and platforms. I do find it entertaining when I see the same person decry ad hominem arguments, but turn around and play up their (or their defendant’s) affiliation, degree, financial status, or social relationships1. We focus on negative ad hominem, but positive ad hominem (“PhD from Harvard” or “he’s a billionaire” or “it was printed in the New York Times”) isn’t formal logic either. We dismiss people all the time because they lack credentials on the subject which they are pontificating — and this is fine2.
This gets to why ad hominem is useful — limited bandwidth. There are only so many voices that can be heard at scale for more than a single tweet. Attention is a limited resource. Like another scenario where there is a limited resource — a hospital emergency room or first responders at an accident — we have to prioritize. Ad hominem functions as rational triage.
Without rational triage — dismissal due to bias & credibility, financial or political motivation — you get inundated with garbage. If instead of saying “this guy previously published papers with lots of fatal errors” I have to go and find all the errors in his latest paper to criticize it, you’ve increased the workload for people trying to do science and decreased the barrier to producing BS. If instead of saying “this guy is funded by oil companies so we don't have to listen to what he says” I have to go and reproduce his research to prove that I understood it, you've increased the workload for people trying to do science and decreased the barrier to propaganda. “Oh, they didn't disclose the fact that their study was funded by Amazon? Well, maybe we should ignore what they have to say about labor markets.” Ad hominem, sure. But also, addressing bias.
And when I say workload, I mean workload. Genuinely refuting a paper without resorting to ad hominem3 takes a long time (e.g. here). You have to carefully read the paper, check the data, read the citations, and otherwise engage in a mini-research project.
It’s pretty easy for me to deal with the mountains of garbage race science because none of those people ever wrestle with the remarkable coincidence that they happen to be a White person finding that White people have higher IQ in their papers — or a male author of a statistical study finding men are better at math. I mean if I wrote a paper quantifying the myriad ways in which Jason Smith is awesome4, you’d think you might laugh instead of engaging with it. But there are actually people out there who read “White research group finds White people have higher IQ” and link to it on Twitter. Ad hominem is the right tool for this job.
The uniformity of nature reduces the workload in empirical science in recognition of the limited bandwidth — we can’t watch the sun an infinite number of times to prove that it will come up every morning5. The uniformity of human nature, that people respond to incentives and hold biases, reduces the workload in rational discourse in recognition of limited bandwidth — we can’t engage with every argument from everyone. Neither are logical deductions, but logic is only a small part of the way we rationally face the world.
Side note: you know what an excellent shortcut in rational discourse is? Anyone who refers to the criticism they are receiving as ad hominem attacks. Almost certainly this means their critics are worth a listen.
I’m also on the record of being in favor of elite cancellation for any reason whatsoever simply due to the discourse-distorting effects of elite representation bias.
In fact, we don’t do it enough. I mean Matt Yglesias has only an undergrad philosophy degree. This isn’t to say you can’t build credentials. But you do that through doing good work, leaning over backwards, and otherwise not being wrong over and over again.
But also building a case for future ad hominem dismissal when you encounter the same issues over and over.
I’m actually pretty miserable, personally.
I mean, it won’t. Eventually.