How Moral Relativism Challenges the Idea of Universal Ethics

The Anthropologist Who Made Philosophers Uncomfortable

In 1906, William Graham Sumner published Folkways, a systematic anthropological study documenting the radical diversity of moral practices across human cultures. Practices condemned as atrocities in one society were honored as religious duties in another. Infanticide, human sacrifice, cannibalism, polygamy, and torture all appeared in Sumner's catalogue as morally sanctioned practices within specific cultural contexts. His conclusion was direct: "the notion of right is in the folkways. It is not outside of them, of independent origin, and brought to test them." Morality was a cultural product, not a universal standard. The right is whatever the group defines as right.

Sumner's position—subsequently labeled descriptive moral relativism—was largely uncontroversial as an empirical claim: cultures do, in fact, differ substantially in their moral codes. The philosophically loaded move is normative moral relativism: not merely that cultures differ, but that no cross-cultural moral judgments are warranted, that there is no standpoint outside cultural frameworks from which practices can be evaluated as objectively right or wrong. This position has genuine philosophical defenders and genuine philosophical problems, and the debate between relativists and universalists remains one of the most practically significant in contemporary ethics.

Three Forms of Moral Relativism

Moral relativism is not a single position but a family of related claims that differ in scope and strength.

The progression from descriptive to meta-ethical to normative relativism involves increasingly strong philosophical commitments. Gilbert Harman's defense of moral relativism in his 1975 paper "Moral Relativism Defended" in Philosophical Review focused on inter-personal and inter-group moral claims: moral judgments, he argued, are implicit agreements or conventions, and their truth is relative to the relevant agreement framework. This is a form of contractualism about moral truth, not a claim that anything goes—moral requirements exist within frameworks, even if no framework has universal standing.

The Argument from Cultural Diversity

The most common argument for moral relativism begins with the empirical diversity of moral practices and concludes that there are no objective moral truths. If there were objective moral truths, the argument runs, we would expect greater cross-cultural agreement, similar to the agreement we observe in empirical matters like mathematical calculations or basic physics. The persistence of fundamental moral disagreement across cultures suggests that moral "facts" do not exist independently of cultural frameworks.

• Critics note that descriptive diversity does not entail meta-ethical relativism—disagreement about a question does not imply there is no correct answer
• Ethical disagreements may often reflect differing factual beliefs rather than truly different ultimate values—cultures that practice human sacrifice to appease deities share the value of community welfare; they differ on the empirical question of what the gods require
• James Rachels argued in his 1986 essay "The Challenge of Cultural Relativism" that the argument from diversity is formally invalid: moral diversity proves only that people disagree, not that they are all equally right
• Recent cross-cultural psychology research has documented striking moral universals across populations that had no historical contact—suggesting some moral intuitions may be species-wide rather than culturally constructed

Moral Universalism: The Case for Cross-Cultural Standards

The principal alternatives to moral relativism are forms of moral universalism: the view that at least some moral claims are true or false independently of cultural endorsement. Moral realism holds that objective moral facts exist, analogous to physical facts, and that moral progress—like the abolition of slavery—is genuine discovery rather than mere cultural change.

J.L. Mackie's error theory, presented in Ethics: Inventing Right and Wrong (1977), agreed with relativists that there are no objective moral facts but rejected relativism: rather than holding that moral claims are true relative to cultural frameworks, Mackie held that all moral claims are false because they purport to be about objective features of the world that do not exist. This position—moral nihilism or moral skepticism—is more radical than relativism and more challenging for everyday moral practice.

The Tolerance Paradox and Self-Refutation

Normative moral relativism faces a well-known internal tension. If moral judgments are valid only within cultural frameworks, then the claim "one ought to tolerate other cultures' practices" must itself be relative. It has no universal validity. But normative relativists typically present tolerance as a universal requirement, applicable across cultures. This creates a self-refuting structure: to assert that everyone ought to be tolerant of cultural differences is to make a cross-cultural moral claim, which is precisely what normative relativism disallows.

Martha Nussbaum's capabilities approach, developed with Amartya Sen, attempted to establish a minimal set of universal human goods—including bodily health, emotional development, practical reason, and affiliation—that transcend cultural relativism without imposing a single thick conception of the good life. The approach argues that practices which systematically damage human capabilities can be evaluated critically across cultural contexts, because the capabilities they damage are universally important regardless of cultural endorsement.

• Nussbaum applied the capabilities approach specifically to women's welfare, arguing that cultural relativism has been used to shield gender-based oppression from external critique
• Research by Jonathan Haidt and colleagues identifies five to six moral "foundations" that appear cross-culturally—care, fairness, loyalty, authority, sanctity, and liberty—though cultures weight them differently
• The fact that cross-cultural moral criticism is logically coherent does not imply that it is always epistemically reliable—critics of other cultures frequently project their own framework's assumptions onto practices they observe only superficially

The most defensible contemporary position is neither pure universalism nor full relativism. Moral universalism need not claim certainty about a complete moral code—it claims only that some moral judgments can be warranted across cultural boundaries and that the abolition of chattel slavery, for example, was genuine moral progress rather than mere cultural preference change. Relativism contributes the crucial reminder that cultural particularity shapes moral perception in ways that demand epistemic humility. Both insights are required for honest ethical reasoning in a pluralistic world.