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Moral realism claims that moral facts exist objectively and independently of individual beliefs, cultures, or minds. Antirealism denies this: moral facts (if they exist at all) depend on minds, cultures, or conventions. This is the fundamental metaethical divide: it shapes how we understand moral language, epistemology, and disagreement. Realists must explain what moral facts are and how we know them; antirealists must explain why moral discourse seems assertive if not fact-stating.
Examine a seemingly objective moral claim ('slavery is wrong') and ask: would this be true even if all minds disagreed? Could we be systematically mistaken about it? Different answers align with realism or antirealism. Survey specific realist and antirealist positions to see how each addresses the core challenges.
Equating realism with dogmatism or antirealism with nihilism. Assuming realism requires certainty or infallibility in moral knowledge. Treating the divide as purely binary when positions like constructivism occupy middle ground.
From your study of metaethics, you know that metaethics asks not "what should I do?" but "what kind of thing are moral claims?" The realism/antirealism debate is the deepest divide within metaethics — it concerns whether moral reality exists independently of the minds that think about it. A moral realist holds that when someone says "slavery is wrong," they are stating a fact that is true (or false) regardless of whether any person, culture, or society believes it. The wrongness is out there in the world, not projected onto it. An antirealist denies this: moral claims are not objective facts, but expressions of attitude, social agreement, cultural convention, or something else mind-dependent.
The best way to feel the pull of both sides is through a single test case. Ask: "Would torturing children for fun be wrong even if every human being on earth approved of it?" Most people's intuition is: yes, obviously — approval doesn't make it right. That intuition is the realist instinct. Now ask: "What exactly is this moral fact — where does it live, how do we detect it, and why should we trust our moral intuitions as trackers of it?" Those questions make realism hard to defend. The antirealist says: there is no such spooky fact; moral claims express attitudes, enforce norms, or coordinate behavior — and they work perfectly well without positing independent moral facts.
Antirealism comes in several varieties that respond differently to this challenge. Error theory (J.L. Mackie) accepts that moral claims purport to state facts, but argues all such claims are false because the facts they require don't exist — moral discourse is a systematic error. Non-cognitivism (including expressivism) denies that moral claims purport to state facts at all; "Torture is wrong" expresses disapproval rather than describing the world, so it can't be true or false. Relativism holds that moral facts do exist, but only relative to a culture or individual — so slavery can be "wrong for us" and "not wrong for them" simultaneously.
The debate has two major pressure points. Realists must answer the ontological question: what kind of entity is a moral fact, and does it fit with a naturalistic picture of the world? They must also answer the epistemological question: how do we come to know moral facts, given that we can't observe them the way we observe physical objects? Antirealists, on the other hand, must explain why moral discourse *looks* like fact-stating — we argue about morality, revise our views, and call each other wrong — if it's not actually tracking facts. This is the Frege-Geach problem: if "murder is wrong" just expresses disapproval, what does "if murder is wrong, then hiring a murderer is wrong" express? Logical connectives seem to require that moral sentences have truth conditions.
Neither side has a clean victory, which is why the debate remains live. A useful framing: realism and antirealism are not just abstract positions — they shape how you read moral arguments. A realist thinks moral progress is genuinely discovering more of morality's structure (like discovering facts about physics). An antirealist thinks moral progress is something else — attitude refinement, social negotiation, expanding empathy — without any pre-existing map to discover. Both framings illuminate real features of moral practice, which is why even after settling the metaethical question, something important about morality is left to explain.
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