Yes, I wasn’t claiming that it’s good use of Bayes’ theorem. The “sort of” qualification is significant, although I don’t think that the use of the “worst case reference class” prevails in practice :-).
The claim that I intended to make is that “Bayes’ theorem implies that the presence of a feature of a member of a given reference class is evidence for the presence of the feature in other members of the reference class.” This is technically correct. It’s not good epistemology in full generality, for the reason that Qiaochu gives. I’ll modify my post to make what I was trying to say more clear.
Yes, I wasn’t claiming that it’s good use of Bayes’ theorem. The “sort of” qualification is significant, although I don’t think that the use of the “worst case reference class” prevails in practice :-).
I think most readers will read the phrase “This is just Bayes’ theorem” as “This is correct use of Bayes’ theorem.”
The claim that I intended to make is that “Bayes’ theorem implies that the presence of a feature of a member of a given reference class is evidence for the presence of the feature in other members of the reference class.” This is technically correct. It’s not good epistemology in full generality, for the reason that Qiaochu gives. I’ll modify my post to make what I was trying to say more clear.