Meta-ethics investigates the foundations, status, and meaning of moral claims, asking whether moral statements express objective truths, subjective feelings, or something else entirely. One major position is moral realism, the view that there are objective moral facts that exist independently of human beliefs, attitudes, or conventions. The opposing view, moral nihilism or ethical nihilism, holds that nothing is morally right or wrong and that moral statements do not express truths. Between these extremes lie positions such as moral absolutism, which asserts that certain actions are intrinsically right or wrong regardless of context, and moral relativism, which holds that moral judgments are not universally valid but relative to cultural, societal, or individual standards.
Moral relativism takes several forms. Descriptive moral relativism observes that moral beliefs differ across cultures, while normative moral relativism claims that no culture's moral standards are objectively better than another's. Cultural relativism holds that moral standards are determined by cultural context with no universal yardstick. A major criticism of these views is that they risk moral tolerance of atrocities: if all cultural practices are equally valid, one seemingly cannot condemn practices like slavery or genocide in other cultures. Moral subjectivism pushes relativism further by holding that moral statements express personal attitudes or preferences, with truth or falsehood determined individually. Emotivism, associated with A.J. Ayer and C.L. Stevenson, captures this idea with the slogan that "stealing is wrong" simply means "boo to stealing," an emotional utterance rather than a factual claim.
Several famous challenges shape this terrain. G.E. Moore identified the naturalistic fallacy as the error of defining moral properties like "good" in terms of natural properties like pleasure, conflating what is the case with what ought to be the case. David Hume's is-ought problem states that one cannot derive moral conclusions solely from factual premises without an additional moral premise. The Euthyphro dilemma, drawn from Plato, asks whether an action is good because God commands it or whether God commands it because it is good, posing deep difficulties for divine command theory, which holds that moral obligations are determined by God's will. Moral particularism, advanced by Jonathan Dancy, challenges the existence of universal principles by arguing that moral judgments should be made case by case, while moral pluralism acknowledges that multiple irreducible moral values such as justice, care, and liberty may conflict, with no single principle always taking priority.