Moral relativism

Moral relativism is the view that moral judgments are not universally valid but are relative to cultural, social, or individual frameworks. In its strongest form, it denies the existence of objective moral truths altogether, holding that when two cultures or individuals disagree about a moral question, neither is objectively right or wrong — each is simply applying a different standard, and there is no neutral standpoint from which to adjudicate between them. The position has been a persistent presence in Western philosophy since at least Protagoras in the fifth century BCE, but it gained its greatest intellectual momentum in the twentieth century through the development of cultural anthropology and the growing awareness of deep moral diversity across human societies.^{1, 14}

Moral relativism is not a single thesis but a family of related positions that differ in scope and philosophical ambition. Understanding the debate requires distinguishing carefully among them, because the arguments for and against each variety are substantially different. The descriptive claim that moral beliefs vary across cultures is far less controversial than the metaethical claim that there are no culture-independent moral truths, and conflating the two has been a persistent source of confusion in both popular and philosophical discussions.^{1, 17}

Varieties of moral relativism

Philosophers standardly distinguish three forms of moral relativism: descriptive, metaethical, and normative. Descriptive moral relativism is the empirical observation that different cultures hold different moral beliefs. This is a claim in anthropology and moral psychology, not in philosophy, and it is largely uncontroversial. Societies differ on questions ranging from the permissibility of polygamy and infanticide to the relative weight of individual rights versus communal obligations. The existence of such variation is well documented and not seriously disputed.^{1, 5}

Metaethical moral relativism makes the stronger philosophical claim that the truth or falsity of moral judgments is not absolute but relative to the moral framework of the person or culture making the judgment. On this view, the statement "infanticide is wrong" is not true or false simpliciter; it is true relative to some moral frameworks and false relative to others, and there is no framework-independent fact of the matter. This is a claim about the nature of moral truth itself, and it is the version of relativism that generates the most substantive philosophical debate. Gilbert Harman has been the most prominent defender of this position in contemporary analytic philosophy, arguing that moral judgments are implicitly relational — they express a relation between an act and a set of moral standards, much as the claim that "X is to the left of Y" is implicitly relational and has no truth value unless the frame of reference is specified.^{2, 3}

Normative moral relativism is the prescriptive claim that one ought not to impose one's own moral standards on members of other cultures. This is the version most commonly encountered in popular discourse and introductory ethics courses, and it is also the most philosophically problematic, because it appears to presuppose the very kind of universal moral principle (a duty of tolerance) that relativism is supposed to deny. Bernard Williams called this the "vulgar" form of relativism and argued that it is incoherent: the injunction to tolerate other cultures' moral practices is itself a substantive moral claim that purports to be universally binding.^{1, 17}

Historical roots

The philosophical roots of moral relativism extend to the pre-Socratic period. Protagoras of Abdera (c. 490–420 BCE) is reported by Plato to have held that "man is the measure of all things, of the things that are that they are, and of the things that are not that they are not." Plato interprets this as a relativist thesis in the Theaetetus, arguing that if Protagoras is right, then every person's judgment is equally true, which would make the very concept of expertise meaningless and undermine the possibility of rational disagreement. Whether Protagoras himself intended his doctrine to extend to moral judgments or only to perceptual ones is debated, but the relativistic reading became the standard interpretation in the history of philosophy.¹⁴

Michel de Montaigne (1533–1592) gave the relativist impulse its most influential early modern expression. In his essay "Of Cannibals" (1580), Montaigne described the customs of the Tupí people of Brazil and argued that European judgments of their practices as "barbarous" reflected nothing more than the power of cultural habituation. "Each man calls barbarism whatever is not his own practice," Montaigne wrote, "for indeed it seems we have no other test of truth and reason than the example and pattern of the opinions and customs of the country we live in." Montaigne did not develop a systematic metaethical theory, but his essays became a touchstone for later thinkers who sought to challenge the assumption that European moral standards were universally valid.¹⁵

The Finnish philosopher and anthropologist Edward Westermarck (1862–1939) produced the first systematic philosophical defence of moral relativism in the modern sense. In The Origin and Development of the Moral Ideas (1906–1908) and Ethical Relativity (1932), Westermarck argued that moral judgments are expressions of emotional attitudes rather than statements of objective fact, and that the diversity of moral beliefs across cultures reflects genuine differences in moral sentiment rather than varying degrees of insight into a single moral reality. Westermarck combined empirical anthropological evidence with a philosophical analysis of moral language, anticipating the emotivist theories of A. J. Ayer and C. L. Stevenson by several decades.^{4, 1}

Cultural relativism in anthropology

Moral relativism received its most powerful institutional support from the development of cultural anthropology in the early and mid-twentieth century. Franz Boas (1858–1942), the founder of American cultural anthropology, argued against the prevailing evolutionary paradigm that ranked cultures on a scale from "primitive" to "civilised." Boas insisted that each culture must be understood on its own terms, and that the attempt to evaluate other cultures by the standards of Western civilisation was both scientifically invalid and ethically suspect. Although Boas was primarily a methodological relativist — he advocated cultural relativism as a research stance rather than a metaethical thesis — his influence encouraged the broader adoption of relativistic attitudes in the social sciences.^{5, 1}

Melville Herskovits (1895–1963), a student of Boas, made the transition from methodological to normative relativism explicit. In his 1947 statement to the United Nations Commission on Human Rights, Herskovits argued that the proposed Universal Declaration of Human Rights was an expression of Western cultural values and could not claim universal validity. "Standards and values are relative to the culture from which they derive," Herskovits wrote, "so that any attempt to formulate postulates that grow out of the beliefs or moral codes of one culture must to that extent detract from the applicability of any Declaration of Human Rights to mankind as a whole." The statement was widely discussed and widely criticised, but it crystallised the tension between cultural relativism and the universalist assumptions underlying international human rights law.⁵

Harman’s moral relativism

Gilbert Harman’s metaethical relativism, developed primarily in The Nature of Morality (1977) and Moral Relativism and Moral Objectivity (1996, co-authored with Judith Jarvis Thomson), is the most rigorously argued philosophical defence of moral relativism in the analytic tradition. Harman argues that moral judgments are best understood as implicitly relational: when we say that an action is wrong, we mean that it is wrong relative to a particular set of moral standards, even if the relativisation is not explicitly stated. The analogy is to claims about motion: to say that an object is moving is incomplete unless we specify a frame of reference, because motion is inherently relational. Similarly, Harman contends, moral wrongness is relational — it obtains only relative to a framework of moral agreements.^{2, 3}

Harman’s argument rests in part on an appeal to moral explanations. He argues that moral facts are never needed to explain our observations. When we observe someone pouring gasoline on a cat and setting it on fire, our moral disapproval is fully explained by our psychological dispositions and the moral norms of our society; we do not need to posit an objective moral fact — that the act is really, mind-independently wrong — to account for our reaction. This "argument from the explanatory impotence of moral facts" is meant to show that there is no empirical evidence for the existence of objective moral truths, and that the most parsimonious account of our moral experience does not require them.³

Judith Jarvis Thomson replies to Harman in the same volume, defending a form of moral objectivism. Thomson argues that Harman’s analogy between moral judgments and claims about motion is flawed: while "X is moving" is genuinely incomplete without a reference frame, "torturing children for fun is wrong" does not seem to require implicit relativisation in the same way. Thomson contends that Harman’s position ultimately reduces moral disagreement to mere difference in taste — a consequence that, she argues, does not do justice to the phenomenology of moral conviction.²

The moral argument for God’s existence

The relationship between moral relativism and theism has been a central theme in the philosophy of religion. A number of theistic philosophers have argued that objective moral values and duties exist, that their existence requires a transcendent ground, and that this ground is best identified with God. On this view, if moral relativism is false and moral realism is true, this constitutes evidence for theism — because the existence of objective moral truths would be unexplained (or at least deeply puzzling) in a purely naturalistic universe.¹⁶

C. S. Lewis advanced a version of this argument in Mere Christianity (1952), contending that the existence of a universal "moral law" that all humans recognise, despite their cultural differences, points to a moral Lawgiver. Lewis argued that cross-cultural moral agreement on basic principles (prohibitions against murder, theft, and lying) is best explained by the existence of an objective moral standard implanted in human nature by God. The argument depends on the claim that moral relativism is false — that there are genuine cross-cultural moral universals that require explanation.¹⁶

The moral argument faces challenges from both directions. Moral relativists deny the premise that objective moral values exist, and therefore reject the argument at its first step. Secular moral realists accept that objective moral values exist but deny that they require a theistic ground, arguing instead that moral facts are sui generis — brute facts about the nature of value that do not need to be explained by anything external to themselves. The debate between these positions is one of the most active areas of contemporary philosophy of religion.^{8, 1}

Critiques of moral relativism

Moral relativism has faced a battery of philosophical objections, several of which have proved difficult for relativists to answer satisfactorily. The most frequently cited is the self-refutation objection. If the relativist claims that "no moral judgment is universally true," this claim itself appears to be a universal moral (or metaethical) judgment. If it is true, then at least one universal claim is true, which contradicts the relativist thesis. Relativists have responded by distinguishing between first-order moral claims (which are relative) and second-order metaethical claims (which can be universal without inconsistency), but critics contend that this distinction is difficult to maintain in practice, since the normative implications of relativism (particularly the tolerance principle) inevitably involve first-order commitments.^{1, 17}

A second major objection concerns moral progress. If moral judgments are true only relative to a cultural framework, then it is unclear how we can speak of moral progress — the abolition of slavery, the extension of civil rights to women and minorities, the prohibition of torture. These changes appear to represent genuine improvements, not merely changes in cultural preferences. But on a strictly relativist account, the slaveholder’s moral framework was true for his society at the time, and our current framework is true for ours; neither is objectively better than the other. This consequence strikes many philosophers as a reductio ad absurdum of the relativist position.^{1, 13}

The tolerance paradox, closely related to the self-refutation objection, poses a further difficulty. Normative relativism enjoins tolerance of other cultures' moral practices, but tolerance is itself a substantive moral value. If a culture practices intolerance — if, for example, it endorses the persecution of religious minorities or the subjugation of women — the relativist faces a dilemma: to condemn the intolerant culture is to impose an external moral standard, violating the relativist principle; but to tolerate the intolerance is to endorse moral practices that the relativist presumably finds abhorrent. Karl Popper identified this as the "paradox of tolerance" in The Open Society and Its Enemies (1945), and it remains one of the most trenchant objections to normative relativism.¹

Alasdair MacIntyre has offered a distinct critique from the standpoint of virtue ethics. In After Virtue (1981), MacIntyre argues that moral relativism is not a coherent philosophical position but a symptom of the collapse of the Enlightenment project of grounding morality in universal reason. On MacIntyre’s view, the apparent intractability of modern moral disagreement reflects the fact that contemporary moral discourse draws on fragments of incompatible moral traditions, each of which possesses its own internal logic but none of which can claim universal rational authority. The solution, MacIntyre argues, is not relativism but a return to tradition-constituted inquiry — the recognition that moral reasoning is always conducted from within a particular tradition, while insisting that traditions can be rationally evaluated and compared.¹¹

Moral realism as alternative

The principal philosophical alternative to moral relativism is moral realism: the view that there are objective moral truths that hold independently of what any individual or culture believes. Moral realism comes in both naturalist and non-naturalist varieties. Naturalist moral realists, such as Peter Railton and Richard Boyd, argue that moral facts are a species of natural fact — facts about human flourishing, well-being, or evolutionary fitness — and are in principle discoverable by empirical investigation. Non-naturalist moral realists, such as Russ Shafer-Landau, hold that moral facts are sui generis: they are real and objective but not reducible to natural facts.⁸

Shafer-Landau’s Moral Realism: A Defence (2003) presents the most comprehensive case for non-naturalist moral realism in recent analytic philosophy. Shafer-Landau argues that moral truths are necessary truths, analogous to mathematical truths: just as the truth of "2 + 2 = 4" does not depend on anyone believing it, the wrongness of gratuitous cruelty does not depend on any culture's moral framework. He responds to Harman's explanatory impotence argument by contending that moral facts do play an explanatory role — for example, the injustice of apartheid helps explain why it generated resistance — and that the failure to observe moral facts empirically is no more damaging to moral realism than the failure to observe mathematical objects empirically is to mathematical realism.⁸

J. L. Mackie occupies an interesting intermediate position. In Ethics: Inventing Right and Wrong (1977), Mackie argues that moral realism is false — there are no objective moral values — but does so on metaphysical grounds (the "argument from queerness," which holds that objective moral properties would be metaphysically strange entities unlike anything else in the natural world) rather than on relativist grounds. Mackie’s position is moral error theory: ordinary moral discourse presupposes objective moral facts, but this presupposition is false. This shows that one can reject moral realism without embracing relativism; error theory and relativism are distinct anti-realist positions with different implications.⁹

Empirical evidence from cross-cultural moral psychology

The empirical debate over moral relativism has been transformed in recent decades by work in cross-cultural moral psychology. Jonathan Haidt’s moral foundations theory, developed through extensive cross-cultural research and presented in The Righteous Mind (2012), identifies at least five (later six) psychological foundations underlying moral judgment: care/harm, fairness/cheating, loyalty/betrayal, authority/subversion, sanctity/degradation, and liberty/oppression. Haidt argues that all cultures draw on these foundations, but they weight them differently: Western, educated, industrialised, rich, democratic (WEIRD) populations tend to emphasise care and fairness while downplaying loyalty, authority, and sanctity, whereas many non-Western populations weight all five or six foundations more equally.^{6, 12}

This finding is ambiguous for the relativism debate. On one hand, the existence of universal moral foundations suggests that human moral psychology is not a blank slate shaped entirely by culture, which counts against strong relativism. On the other hand, the dramatic variation in how these foundations are weighted and applied across cultures suggests that the specific moral judgments people reach are heavily culturally conditioned, which lends support to at least descriptive relativism. Haidt himself does not endorse metaethical relativism, but his work has been cited by both sides of the debate.⁶

Joseph Henrich’s critique of the WEIRD problem has added a further dimension. In The WEIRDest People in the World (2020), Henrich documents the extent to which the populations used in most psychological research — Western, educated, industrialised, rich, and democratic — are statistical outliers on a wide range of psychological measures, including moral intuitions. Henrich argues that WEIRD populations are psychologically unusual in their emphasis on individual rights, impartial fairness, and universalist moral principles, and that these commitments are historically contingent products of specific institutional and cultural developments (particularly the Catholic Church's dissolution of kin-based social structures in medieval Europe). If Henrich is right, then even the moral intuitions that seem most self-evident to Western philosophers — such as the wrongness of nepotism or the priority of individual rights over communal obligations — are culturally particular rather than universally shared.⁷

Joshua Greene’s work in Moral Tribes (2013) offers a complementary perspective. Greene argues, on the basis of neuroscientific and behavioural evidence, that human moral cognition operates through two systems: a fast, automatic, emotion-driven system that generates moral intuitions, and a slow, deliberate, reasoning-based system that can override those intuitions. Greene contends that the intuitive system is calibrated by cultural learning and varies across societies, while the deliberative system is capable of reaching conclusions that transcend cultural boundaries. This dual-process model suggests that both relativists and universalists are partially right: moral intuitions are culturally relative, but moral reasoning can in principle aspire to culture-transcendent conclusions.¹⁸

Contemporary status of the debate

Moral relativism remains a minority position among professional philosophers. The 2020 PhilPapers survey of anglophone philosophers found that roughly 56% endorsed or leaned toward moral realism, while only about 28% endorsed or leaned toward moral anti-realism (a category that includes relativism, error theory, and non-cognitivism). Among metaethicists specifically, the proportion favouring realism is higher. Nevertheless, relativism continues to exert significant influence in anthropology, cultural studies, and popular moral discourse, where the intuition that "who am I to judge another culture?" retains strong appeal.¹

The most productive contemporary work on moral relativism has moved beyond the simple question of whether relativism is true or false and toward more nuanced investigations of how moral frameworks interact, how moral disagreement should be handled in pluralistic societies, and what the empirical evidence from moral psychology and cross-cultural research actually shows about the depth and significance of moral variation. The debate has been enriched by the recognition that the choice is not simply between naive relativism and dogmatic universalism, but involves a spectrum of positions — including Harman’s sophisticated metaethical relativism, MacIntyre’s tradition-constituted inquiry, and the various forms of moral constructivism — each of which attempts to take seriously both the fact of moral diversity and the apparent demands of moral objectivity.^{1, 2, 11}