What Is Metaethics? Definition, Questions & Theories

Direct Answer

Metaethics is the branch of philosophy that studies the nature of morality itself. It does not ask which actions are right or wrong — that is the task of normative ethics, which produces theories such as utilitarianism, deontology, and virtue ethics. Instead, metaethics steps back and asks what is going on when we make moral judgments at all. Its questions fall into three broad families. The first is metaphysical: Do moral properties and moral facts exist, and if so, are they part of the natural world? The second is semantic: What do moral terms such as "good," "right," and "ought" mean, and are moral sentences the kind of thing that can be true or false? The third is epistemological and psychological: How could we come to know moral truths, and how do moral beliefs connect to motivation and action?

The standard map of answers divides along two axes. The first axis is realism versus anti-realism: realists hold that moral truths exist objectively and are independent of what anyone believes; anti-realists deny this, either because they think there are no moral truths at all (error theory and nihilism), or because they think moral truths are only true relative to a culture or individual (relativism), or because they think moral judgments are not truth-apt in the first place (non-cognitivism). The second axis is cognitivism versus non-cognitivism: cognitivists hold that moral judgments express beliefs that can be true or false; non-cognitivists hold that moral judgments primarily express emotions, prescriptions, or attitudes.

Historical Context

The word "metaethics" is twentieth-century, but the questions are ancient. Plato's Euthyphro asks whether the pious is loved by the gods because it is pious, or pious because it is loved — a question about the source and objectivity of moral value. Aristotle's ethics presupposes a teleological naturalism in which the good is grounded in human nature. The modern discussion takes its decisive shape from David Hume, who distinguished facts from values and argued that morality is grounded in sentiment rather than reason, and from Immanuel Kant, who insisted that morality is a matter of rational necessity. The discipline crystallized in 1903 with G.E. Moore's Principia Ethica, which separated the question "what things are good?" from "what does 'good' mean?" and argued that "good" names a simple, non-natural property. Moore's critique of naturalism and his open-question argument launched the modern metaethical debate, which in the twentieth century moved through emotivism, prescriptivism, and a revival of realism.

Key Arguments & Debates

The central debates of metaethics are interconnected. The semantic debate asks whether moral judgments can be true or false. Cognitivists say they can; non-cognitivists — such as the emotivists A.J. Ayer and C.L. Stevenson — say a sentence like "stealing is wrong" is closer to "boo to stealing" than to a factual claim. The ontological debate asks whether moral properties exist. Realists answer yes; error theorists such as J.L. Mackie argue that moral judgments systematically presuppose objective values that do not exist, so all positive moral claims are false. The is-ought problem presses on anyone who wants to ground morality in facts: Hume observed that moral arguments slide from descriptive "is" statements to normative "ought" statements without justification. The motivation debate asks how moral judgments relate to action: if moral judgment is a belief, how does it move us to act? If it is an attitude, how can we reason about it? Finally, moral epistemology asks how, if moral truths exist, we could come to know them — a challenge for both naturalists and non-naturalists.

Contemporary Relevance

Metaethics may seem abstract, but its questions surface constantly in public life. When people argue about whether moral disagreement across cultures proves that right and wrong are merely relative, they are rehearsing the anti-realist case. When ethicists ask whether facts about well-being can settle debates about animal welfare or AI ethics, they are taking a position on moral naturalism. When skeptics insist that moral claims are just expressions of feeling, they are embracing non-cognitivism. Debates about moral progress, moral disagreement, and the possibility of moral knowledge in an age of cultural fragmentation all presuppose metaethical answers. Understanding the framework allows you to see what is actually at stake in such disputes rather than talking past your opponent.

Related Concepts

Metaethics connects to the whole of the ethical domain. Moral realism and anti-realism names the great divide in metaethics. Moral naturalism holds that moral properties are natural properties; moral non-naturalism, defended by Moore, denies this. The is-ought problem challenges any attempt to derive values from facts, while the naturalistic fallacy names the mistake of identifying goodness with a natural property. Normative theories — utilitarianism, deontology, and virtue ethics — supply the content that metaethics analyzes, and the philosophy of ethics as a whole is organized around these levels of inquiry.

Further Learning

For a comprehensive introduction, consult the Stanford Encyclopedia of Philosophy entry on metaethics. The Internet Encyclopedia of Philosophy's overview of metaethics provides an accessible survey of the positions and their arguments. For the founding text of modern metaethics, read G.E. Moore's Principia Ethica (1903), and for a clear contemporary survey, see Alexander Miller's An Introduction to Contemporary Metaethics (Polity, 2003).