Moral epistemology is the study of moral knowledge and related phenomena. The recorded history of work in the field extends (at least) 2,500 years to Socrates’s inquiries into whether virtue and expertise in governance can be taught. Every major moral theorist since then has advanced theses about the possibility of moral knowledge and those modes of thinking, feeling, and reasoning that are most conducive to improvements in moral outlook. Though the study of moral language and the metaphysics of morality received more attention by Western philosophers in the 20th century, interest in moral epistemology has grown in recent years as theorists have turned to advances in the scientific study of moral development and moral judgment—and their origins in biological and cultural evolution—in the hopes of shedding new light on the old questions. By further understanding the processes that give rise to our moral beliefs, and the critical evaluation and consequent evolution of moral frameworks, we hope to gain further insight into what distinguishes those rational, reasonable, or well-considered moral views that would seem to comprise moral knowledge from those irrational, false, or unduly biased judgments that fall short. This article begins by describing general overviews of moral epistemology, moves on to consider historically important accounts of moral knowledge, and then addresses contemporary scientific accounts of moral judgment, moral development, and the foundations of moral response in our evolved biology. With these elements in place, it moves on to moral skepticism and the question of whether we have any moral knowledge; moral nihilism, or the view that there are no moral truths to be known; and the extent and nature of fundamental moral disagreement: perhaps the most common route to skepticism about morality. The “special” topics that follow these core concerns demonstrate the breadth and richness of the field. We would seem to have “intuitions” of the morality of certain actions, people, or institutions. Some (non-skeptical) theorists liken these intuitions to perceptions of color or beauty. Others argue that desires provide non-inferential knowledge of value, that basic moral principles are self-evident, or that we can directly infer “ought” from “is.” Theorists discuss, among other things, the reliability of ordinary processes of moral judgment, the role of coherence and reflection in augmenting the rationality of folk moral views, the possibility of theoretical moral knowledge akin to scientific knowledge, and the rationality of basing one’s moral views on testimony.
