Originally Posted by
RChung
Back when I was a grad student, the then-chair of the department, a member of the NAS, used to remind us, "Argumentum ad hominem is, 'Your argument is trash because you're a dick,' it's not 'Your argument is trash because of these following reasons, and by the way, you're a dick.'" This is an example of something else entirely: "your argument is okay but you're a dick."
I don't really think the argument is okay. There's a "motte and bailey" thing going on where the carnivore diet folks say "Eating nothing but meat is the healthiest thing in the world" and then, when pressed for evidence beyond anecdotes and fallacious evolutionary arguments, they retreat to the defensible, but qualitatively different, position: "Saturated fats aren't so bad and meat and full-fat dairy might be better for you than some other crap in the modern Western diet." Berry's being a dick is more than incidental to his argument and his obvious conflict of interest.