Metaethics is the philosophical sub-discipline that does not study normative issues (such as which actions are right, what makes a life go better, etc.) but rather second-order questions, questions about (not within) morality. These include the semantics, metaphysics, epistemology, and psychology of morality (and perhaps of other normative discourse). Modern metaethics is said to have emerged at the beginning of the 20th century (perhaps with Moore's Principia Ethica), and dominated the philosophical interest in morality until the 1960s when philosophical study of first-order, normative issues became more popular and influential. But the last decade or so has witnessed a tremendous rise in the philosophical interest in metaethics.

Though not often found in the interdisciplinary literature -- metaethics (in the analytic tradition) is a fairly abstract, professional-philosophical debate -- metaethics is easily characterizable as intersubdisciplinary: one cannot seriously study the metaphysics of morals without possessing at least a good overall grasp of metaphysics; one cannot seriously study moral epistemology without at least a good overall understanding of epistemology; and similarly, it is impossible to me a metaethicist without a good grasp of major theories and arguments in the philosophy of language, mind, and action, and perhaps in aesthetics as well.

Indeed, the metaethical debate has recently become even wider in scope, for it is now widely noted that just as morality is a particular instance of a largely normative discourse, metaethics is a particular instance of metanormativity. Normative discourse also includes, for example, the part of epistemic discourse that deals with obviously normative notions such as justification, entitlement, and reasons for belief. There is a close link between the philosophical problems surrounding moral discourse and those surrounding epistemic discourse. And a comprehensive metanormative theory will need to be general enough to be applied to different kinds of normative discourses (such as morality, the normative part of epistemology, some parts of aesthetic discourse), but also to accomodate the differences between them.