02 Moral Truth and Knowledge

The questions of metaethics

Metaethics asks what moral claims mean, whether they can be true, and how anyone could know them. The claim “It is wrong to punish an innocent person” could report an objective moral fact, express a speaker’s attitude, state a rule accepted by a community, or be a claim that cannot be known. These possibilities are related but distinct: an account of moral truth does not by itself explain how moral knowledge is gained.

Objectivity and realism

Moral objectivism holds that at least some moral judgments are true or false independently of what any particular person or group believes. On this view, a society can be mistaken about its treatment of people, just as it can be mistaken about facts in other areas. Objectivism does not require that people always agree, that moral questions are easy, or that one particular moral theory is correct.

Moral realism is closely related but more specific: moral claims purport to describe facts, and at least some such claims are true. Realists disagree about what makes moral claims true. Some regard moral facts as part of the natural world; others argue that moral facts are not reducible to ordinary scientific facts. The terms are often discussed together, though philosophical accounts distinguish them in different ways.

One argument for objectivity appeals to moral criticism and progress. Condemning a practice as unjust seems to mean more than “I dislike it” or “my group rejects it”: it suggests the practice can be wrong even when approved by those with power. Objectivists take this appearance seriously and hold that moral standards can be used to criticize both individuals and societies.

Disagreement and the challenge to objectivity

Moral disagreement is a major challenge for objectivism. People and cultures have disagreed deeply about punishment, equality, and duties to family. Critics argue that persistent disagreement casts doubt on whether moral inquiry reliably discovers universal truths.

Objectivists reply that disagreement alone does not show there is no fact of the matter; people also disagree in science and history. Moral disagreements may reflect conflicting nonmoral beliefs, self-interest, prejudice, different interpretations of shared principles, or genuine difficulty applying those principles. The strength of the disagreement argument depends on whether moral disagreement is unusually widespread or resistant to explanation.

Attitudes, frameworks, and moral truth

Moral subjectivism makes moral truth depend on attitudes or responses. In a simple individual version, “That act is wrong” might mean “I disapprove of that act.” A judgment is then true or false in relation to a person’s attitude, rather than independently of all attitudes. A difficulty for simple subjectivism is that ordinary moral disagreements often seem to involve more than reports of different feelings: people argue over which judgment is right and try to persuade one another.

Moral relativism broadly holds that the truth or justification of some moral judgments depends on a framework, such as a culture’s norms or a person’s commitments. A relativist might say an act is right according to one community’s moral code but wrong according to another’s. The observation that customs vary is a descriptive claim about cultural diversity; relativism adds a claim about how moral truth or justification works. Relativism also does not automatically entail tolerance: concluding that different practices should be tolerated requires an additional moral principle.

Subjectivism and relativism are related but distinct. Subjectivism typically locates moral standards in an individual’s attitudes, while cultural relativism locates them in a group’s standards. Both differ from objectivism by making moral truth or justification dependent on a perspective. Neither is identical to skepticism: a relativist may hold that moral judgments can be known to be true relative to a particular standard.

Skepticism and alternative theories

Moral skepticism questions or denies one or more claims: that moral truths exist, that moral beliefs can be justified, that moral knowledge is possible, or that people have moral reasons to act. It is not a single theory. A skeptic might accept that moral claims can be true or false but doubt that anyone can know which are true; another might deny that any moral claims are true.

Two further positions clarify the debate. Non-cognitivism holds that moral statements do not function primarily as factual claims: they may express attitudes, prescribe actions, or serve another practical role rather than describe facts that make them true or false. Error theory instead treats moral claims as attempts to describe objective moral facts, but says none are true because the required facts do not exist; J. L. Mackie is a prominent defender of this view.

These positions should not be collapsed into one another. Non-cognitivism challenges whether moral judgments are factual claims; error theory treats them as factual claims that systematically fail; relativism allows truth or justification relative to a framework; and skepticism raises doubts about moral truth, justification, knowledge, or reasons to act.

Possible methods of moral knowledge

Moral epistemology asks how moral knowledge could be possible. Even if some moral claims are true, a further question remains: how could we know them? Several possible sources and methods are considered.

• Reason and principles: Moral judgments can be tested for consistency, and the consequences of general principles can be examined. If someone says keeping promises is usually required but that a promise may be broken whenever doing so is convenient, one can ask whether the proposed exception undermines the principle.

• Experience and consequences: Learning about people’s needs, the effects of policies, and the circumstances of an action can change what someone is justified in believing. Empirical evidence may not settle a moral question by itself, but it can correct factual assumptions on which a judgment depends.

• Moral perception or intuition: Some philosophers argue that people can recognize certain moral truths directly, without deriving them from other beliefs. This proposal faces questions about bias, differences in intuition, and how to distinguish reliable judgment from unexamined reaction.

• Reflective equilibrium: Particular judgments can be compared with general principles and relevant facts, with any part of the set revised when it does not fit well. The aim is a coherent view that survives careful reflection, not merely a collection of first impressions.

Each approach has limits. Reasoning can begin from mistaken premises; experience can be incomplete; intuitions may reflect upbringing or prejudice; and a coherent set of beliefs could still be wrong. Moral inquiry therefore often combines evidence, argument, attention to affected people, and willingness to reconsider assumptions.

What remains contested

A central skeptical challenge is that moral facts may seem difficult to fit into a world described by science, and that moral judgments often motivate action in a way ordinary factual beliefs do not. Realists reply that these features do not by themselves prove moral knowledge impossible. They argue that facts can be known through methods combining evidence and reasoning, and that motivation may arise from how people respond to moral beliefs rather than from a special kind of fact. These replies remain contested.

The positions differ over whether moral claims describe objective facts, depend on a person or framework, or can be known at all. Cultural disagreement and the difficulty of explaining moral facts pose serious challenges, but neither alone settles whether moral truth or moral knowledge exists.