Much of what David Hume said about a wide range of subjects remains of great importance today. In the first volume of his first work, A Treatise of Human Nature, a work in which he articulated a new “science of human nature,” Hume focused on an interrelated set of issues in theory of knowledge, metaphysics, and philosophical psychology. More particularly, he explained how it is that we form such important conceptions as space and time, cause and effect, external objects, and personal identity. At the same time, he offered an equally important account of how or why we believe in the objects of these conceptions - an account of why we believe that causes are necessarily connected to effects, that there are enduring external objects, and that there are enduring selves - even though the human mind is unable to provide a satisfactory proof that these phenomena exist. In the second volume of the Treatise Hume expanded his account of human psychology, focusing on the origin and role of the passions and the nature of human freedom. In the third and final volume of this work he explored the origins and nature of morality. In later works he returned to many of these philosophical issues, but he also made substantial contributions to our understanding of political theory, aesthetics, economics, and philosophy of religion. In addition, he wrote an influential, six-volume History of England, a work published in over 175 editions in the eighteenth and nineteenth centuries, and still in print.

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?).

A KIND OF HISTORY OF MY LIFE

Sir

[1] Not being acquainted with this hand-writing, you will probably look to the bottom to find the Subscription, & not finding any, will certainly wonder at this strange method of addressing to you. I must here in the beginning beg you to excuse it, & to perswade you to read what follows with some Attention, [and] must tell you, that this gives you an Opportunity to do a very good-natur’d Action, which I believe is the most powerful Argument I can use. I need not tell you, that I am your Countryman, a Scotchman; for without any such tye, I dare rely upon your Humanity, even to a perfect Stranger, such as I am.

Sir

Not being acquainted with this hand-writing, you will probably look to the bottom to find the Subscription, & not finding any, will certainly wonder at this strange method of addressing to you. I must here in the beginning beg you to excuse it, & to perswade you to read what follows with some Attention, [and] must tell you, that this gives you an Opportunity to do a very good-natur'd Action, which I believe is the most powerful Argument I can use. I need not tell you, that I am your Countryman, a Scotchman; for without any such tye, I dare rely upon your Humanity, even to a perfect Stranger, such as I am. The Favour I beg of you is your Advice, & the reason why I address myself in particular to you need not be told. As one must be a skilful Physician, a man of Letters, of Wit, of Good Sense, & of great Humanity, to give me a satisfying Answer, I wish Fame had pointed out to me more Persons, in whom these Qualities are united, in order to have kept me some time in Suspense.

David Hume (1711-76) may be best understood as the first postsceptical philosopher of the early modern period. Many of Hume's immediate predecessors, particularly the Cartesians, had attempted to refute philosophical scepticism. In contrast to these predecessors, Hume was a self-proclaimed sceptic who consciously developed a philosophical position that is at one and the same time fundamentally sceptical and fundamentally constructive. His position is sceptical in so far as he shows that knowledge has nothing like the firm, reliable foundation the Cartesians or other rationalists had claimed to give it; his position is constructive in so far as he undertook to articulate a new science of human nature that would provide for all the sciences, including morals and politics, a unique and defensible foundation. For nearly two centuries the positive side of Hume's thought was routinely overlooked - in part as a reaction to his thoroughgoing religious scepticism - but in recent decades commentators, even those who emphasize the sceptical aspects of his thought, have recognized and begun to reconstruct Hume's positive philosophical positions.

Of “late years” there has been, Hume wrote in his Treatise of Human Nature, a controversy that has “so much excited the curiosity of the publick, whether these moral distinctions be founded on natural and original principles, or arise from interest and education” Those who adopted the second of these views-those who traced the alleged distinction between virtue and vice to self-interest and education - had claimed, as Hume puts it, that morality itself has "no foundation in nature" but is, rather, founded merely on the pain or pleasure that arises from considerations of self-interest. In contrast, those who ranged themselves on the other side of this issue - those who said that moral distinctions are founded on natural and original principles - claimed that "morality is something real, essential, and founded on nature" (T 2.1.7, 295-6).