“It goes without saying that our contention that beautiful people are more intelligent is purely scientific (logical and empirical); it is not a prescription for how to treat or judge others. To derive a behavioral prescription (what one ought to do) from a scientific conclusion (what is) would be an example of what Hume (1964/1739) calls the ‘‘naturalistic fallacy.’’”
How annoying it is to read stuff like this is the scientific literature. The phrase mentioned was introduced by GE Moore, not Hume. Hume didn’t even call it “fallacy”. Besides, Moore’s use of the phrase is different from what the author is talking about, which is inferring is from ought, i.e. is/ought fallacy. And lastly, since Hume was an ideal observer theorist, he would be inconsistent to claim that “ought” can never be deduced from “is”, since that is precisely what he is claiming that it can. Although from a special kind of “is”.