In Book 2 of the Treatise of Human Nature Hume reports that a question concerning the foundation of moral distinctions had “of late years” been of great public interest. The question is whether “moral distinctions” (distinctions between virtue and vice) are “founded on natural and original principles,” or arise “from interest and education.” He then suggests that those who traced the distinction between virtue and vice to “self-interest or the prejudices of education” supposed that morality has “no foundation in nature.” In contrast, those who said that moral distinctions are founded on natural and original principles supposed that “morality is something real, essential, and founded on nature” (T 2.1.7.2-3, 5). This debate, as we will see, raised both an ontological question (which features of the world, if any, do our moral judgments reflect?) and an epistemological question (which of our faculties, reason or sense, enables us to grasp moral distinctions?).