Hume's Rejection of Metaphysics in Light of ... Human Nature?
Section 1 of Hume's Enquiry recently struck me as having an odd relationship to all of the other things he's so famous for within philosophy. We get his preparatory remarks about his epistemological project, the flourishes about two types of philosophy (topped off with the comment about anatomy's relationship to art), and then--WABAM--we get a theory of human nature. Humans are reasonable, social, and active, and the good life is one where all of these elements intermix in even proportions. While Hume's basically telling his readers how a careful consideration of epistemology will show that human reason is not capable of making justified metaphysical claims, he insinuates that this constitutes a genuine service on the part of epistemology only because of what it means for human ethical life. In bringing a close to metaphysics, epistemology eliminates a force alleged to be generally hostile--the abstruse philosophy whose superstitions bring about such negative consequences for our more sociable and practical affairs, "overwhelm[ing]" the mind "with religious fears and prejudices." Hume’s assault on metaphysics is motivated by a desire to eliminate error and superstition, but this is because metaphysics means the elevation of philosophy at the expense of genuine human good.

Apparently he just wasn't in much of an is-ought gap mood. It looks to me like we're starting with a fact about ourselves (whether metaphysical or something else) and then moving to nothing less than a condemnation of metaphysics and a plan for its burial--all in the spirit of British modesty, of course.