Moral Realism

What moral realism asserts

The position is built from three theses, and you must accept all three to be a realist.

1. Cognitivism. Moral sentences such as "slavery is unjust" express beliefs and have truth-values. They are not disguised commands ("don't enslave!"), expressions of feeling ("ugh, slavery"), or coordination signals.
2. Some are true. At least some positive moral claims really are true — slavery really is unjust. (Error theorists accept cognitivism but deny truth: every moral claim presupposes objective values that don't exist, so all are false.)
3. Mind-independence. What makes moral claims true is not constituted by the attitudes of any individual or group. Slavery would be unjust even if every person came to approve of it.

Each thesis carves out a different rival. Drop cognitivism and you get Ayer's emotivism or Blackburn's expressivism. Keep cognitivism but drop truth and you get Mackie. Keep truth but drop mind-independence and you get a relativist or response-dependent view (an act is right if my culture says so, or if my idealized self would approve).

Varieties of realism

Variant	What moral facts are	Lead defenders	Signature problem
Non-naturalism	Sui generis, irreducible properties — like mathematical objects	G. E. Moore (Principia Ethica, 1903); Derek Parfit (On What Matters, 2011); David Enoch (Taking Morality Seriously, 2011)	Epistemic access — how do we get in touch with non-physical properties?
Cornell naturalism	Natural properties (well-being, flourishing, harm) — discoverable by something like science	Richard Boyd, Peter Railton, Nicholas Sturgeon (1980s–90s)	Moore's open-question argument: any proposed natural definition leaves "but is it really good?" intelligible
Kantian constructivism	Truths produced by what every rational agent must commit to	Christine Korsgaard (The Sources of Normativity, 1996); John Rawls	Whether "constructed" facts are mind-independent enough to count as realism
Ideal observer theory	What a fully informed, impartial, sympathetic observer would approve	Roderick Firth (1952); Adam Smith's "impartial spectator"	Smuggling: the "ideal" specification appears to do the moral work covertly
Divine command realism	Whatever God commands	Robert Adams; Philip Quinn	The Euthyphro dilemma (covered in our Divine Command Theory article)
Quasi-realism	Surface realist talk built atop expressivist foundations	Simon Blackburn (Spreading the Word, 1984; Ruling Passions, 1998)	Whether "earning the right" to realist talk is enough to be a realist

Worked example: the open-question argument

G. E. Moore's Principia Ethica (1903) launched 20th-century meta-ethics with a single test. Suppose a naturalist proposes that "good" just means "what maximizes pleasure." Then "is what maximizes pleasure good?" should be a closed question — as trivial as "is a vixen a female fox?" But it isn't trivial. A reasonable person, fully understanding both terms, can ask whether maximizing pleasure is good and reach a tentative "no." So "good" cannot mean "what maximizes pleasure." Run the argument against any other natural definition and you get the same result. Moore concluded "good" is a sui generis non-natural property — irreducible, simple, recognized by intuition.

The argument has been pressed back hard. Naturalists distinguish meaning from reference (water means "the clear stuff in lakes" but refers to H₂O); a moral term might similarly refer to a natural property without the identity being analytically obvious. The Cornell realists made this move explicit, treating moral property identifications as a posteriori like scientific kinds. Whether the move works is one of the live debates in meta-ethics; it is the hinge on which the naturalism/non-naturalism battle still turns.

Worked example: Mackie's argument from queerness

J. L. Mackie's Ethics: Inventing Right and Wrong (1977) is the most influential anti-realist book of the past century. He grants the realist the entire surface grammar of morality and then argues no objective values could exist.

His "argument from queerness" has two prongs.

• Metaphysical queerness. Objective moral values would be entities of a very strange sort: built into states of the world, but with an action-guiding magnetism that ordinary natural properties lack. Knowing a wall is brick doesn't motivate; knowing an act is wrong, on the realist picture, intrinsically counts against doing it. No other property in our ontology behaves this way.
• Epistemological queerness. If such properties existed, we would need a faculty to detect them — moral intuition. But the realist has not provided a credible account of how that faculty works, what it tracks, or why we should trust it. By contrast, perception, memory, and inference all have well-understood causal stories.

Realist replies. Non-naturalists like Enoch accept the queerness but argue it's tolerable: mathematical and modal facts are also non-natural, and we are willing to accept them because they earn their keep. The cost of realism is a few queer entities; the cost of denying realism is losing the literal truth of "Hitler did wrong." The cost-benefit favors realism. Naturalists deny the queerness from the start: moral properties are perfectly ordinary natural properties, detected by ordinary cognition.

Worked example: Sharon Street's debunking dilemma

In A Darwinian Dilemma for Realist Theories of Value (2006), Sharon Street offers what she calls "the most serious challenge moral realism has ever faced." Her argument starts from a concession every realist must make: our moral beliefs were shaped by evolutionary pressures favoring kin-selection, reciprocal altruism, and group cohesion. Now ask whether those pressures track mind-independent moral truths.

• Suppose yes. Then we need an explanation of why fitness-enhancing beliefs would also be true beliefs about a free-floating moral reality. Evolution selects for survival, not truth; the realist owes us a story of why those two coincided.
• Suppose no. Then our moral beliefs are off-track distortions of any actual moral reality. We have no reason to think slavery really is wrong; that judgment is just what evolution happened to deliver.

Either branch costs the realist. Enoch's reply, the "third-factor explanation," argues that some property — say, well-being — is both fitness-enhancing and morally good. Selection promoting beliefs about it tracks a moral fact even though selection didn't aim at the moral fact. Whether this rescue is enough is one of the most active disputes in current meta-ethics.

Counterarguments and replies

The argument from disagreement. Cultures across history have endorsed slavery, infanticide, religious persecution, and human sacrifice. If moral facts are real, why is convergence so weak? Realist reply: physics had two thousand years of bad cosmology before convergence; moral disagreement is often surface deep, hiding a shared core (don't kill the innocent; protect the weak) plus disputed empirical premises (who counts as innocent; whether slaves are persons).

The motivation puzzle (internalism). Sincere moral judgments seem to motivate intrinsically; beliefs about facts don't. So moral judgments aren't beliefs about facts. Realist reply: motivational internalism is plausible only if we add stipulations the data don't support — depressed and akratic agents make sincere moral judgments without being moved by them.

Queerness, again. Even granting that mathematical platonism is acceptable, moral facts have to do extra work — they bind agents to act. Realist reply: that extra work is just what makes them moral rather than mathematical; demanding they look like ordinary natural facts misses the point.

Quasi-realism. Simon Blackburn argues you can have all the surface conveniences of realism — truth-talk, embedding in conditionals, moral progress — on an expressivist foundation. So realism's distinctive metaphysics is doing no real work. Realist reply: if quasi-realism succeeds in earning every realist conclusion, perhaps it has just become a complicated way of being a realist.

Common confusions

• Realism is not absolutism. A realist can think moral truths are highly context-sensitive — "lying is wrong here, in this context, given these stakes" — and still hold that the contextual truth is mind-independent.
• Realism is not religious. Most professional realists are secular. Divine command theory is one realist option among many; non-naturalists like Parfit are explicitly atheistic.
• Realism does not require infallibility. Realists can hold our current moral beliefs are riddled with error, just as our physics was riddled with error before relativity. The view is that moral beliefs aim at facts, not that they hit them reliably.
• "Subjective" vs "objective" is a distraction. The realist debate is about mind-independence (does the truth depend on what people think?) not about certainty or scope. A subjective experience like a headache is mind-dependent; a fact about the headache (that it began at 3pm) is mind-independent.
• Disagreement isn't evidence against realism by itself. Persistent disagreement among inquirers exposed to the same data does erode confidence; surface disagreement hiding deeper convergence does not.

Why it matters

• Moral progress. Realism gives a clean reading of "we used to think slavery was permissible, but we were wrong." Anti-realists must redescribe progress as preference change.
• Cross-cultural criticism. If moral facts are real, foreign practices (genital cutting, caste systems) can be wrong even if locally endorsed.
• Practical force. Realism explains why "but is it really wrong?" is not a category mistake — it's a question the realist takes literally.
• Foundations for normative ethics. Utilitarianism, Kantian deontology, and virtue ethics are typically presented as realist projects; their truth conditions presuppose moral facts to discover.
• Connection to philosophy of language. The realism debate is the moral parallel of debates over scientific realism, mathematical platonism, and modal realism — meta-ethics tracks general questions about what counts as a fact.