He gets his jollies from peeking into the girls' locker room.
Notice that the suggested rationale for the above coextensivity claim is not given by a broadly behaviourist account of belief, but an interpretationist account of mental states.
In actual fact, it is hard to see how anyone could defend the prescriptive approach. In any other field of enquiry, it would be seen as patently absurd. What would we say of the social anthropologist who, instead of describing the way a given society is, sets about prescribing the way he thinks it ought to be? (We'd probably suggest he ought to give up Anthropology and take up Politics!) …
An Amorous Pædant at the same Time whips And makes Adresses to the School Boys hipes[…]