A Critique of Moral Realism: An Argument from Metaphysical and Epistemological Incoherence
Introduction
The proposition that certain actions are not merely disapproved of, but are objectively wrong, serves as a foundational assumption in much of our normative discourse. This position, known in metaethics as moral realism, holds that moral statements (e.g., “genocide is wrong”) are truth-apt propositions whose truth or falsity is determined by a mind-independent moral reality. The appeal of this view is undeniable; it provides a seemingly firm basis for condemning atrocities, advocating for universal human rights, and imbuing ethical claims with categorical force.
Despite its intuitive appeal and political utility, we contend that moral realism fails as a coherent philosophical position. The purpose of this essay is to articulate a two-pronged argument against it. Our critique is not aimed at the first-order normative content of ethics (e.g., that we ought not inflict gratuitous suffering), but at the second-order, metaethical claim about the status of such norms. We shall argue that moral realism is both metaphysically problematic and epistemologically unsubstantiated. We will proceed as follows: first, we will examine the ontological difficulties inherent in the concept of objective moral properties, drawing on what J.L. Mackie famously termed the “Argument from Queerness.” Second, we will deploy the “Argument from Disagreement” to show that the realist’s epistemic claims are weak. Finally, we will propose that rejecting realism does not lead to a normative void but rather reframes ethics as a constructive human enterprise.
I. The Ontological Objection: The Queerness of Moral Properties
The first, and perhaps most formidable, objection to moral realism is ontological. If there are objective moral facts, then there must be something in the world that makes our moral propositions true. The critical question is: what is the nature of these truth-makers? Unlike scientific propositions, which correspond to observable regularities and physical properties in the natural world (e.g., “water is H2O”), moral propositions appear to refer to nothing empirically detectable. There is no particle, force, or observable state of affairs that constitutes the property of “wrongness.”
This points to the central difficulty: moral properties, if they were to exist as objective features of reality, would be metaphysically queer. They would be unlike anything else in our ontology. To say that an action possesses the property of “wrongness” is not like saying it possesses the property of “being a cause of pain.” The latter is a descriptive, natural property. The former, however, is a normative one, purportedly containing an inherent “to-be-doneness” or “not-to-be-doneness.” As David Hume noted, one cannot logically derive an “ought” from an “is.” Moral realists who are also naturalists attempt to bridge this gap by identifying moral properties with complex natural properties (e.g., “that which maximizes well-being”). Yet these reductive accounts invariably face the open-question argument: one can always meaningfully ask, “But is maximizing well-being good?”
If moral properties are not natural, then they must be non-natural, existing in some Platonic or abstract realm. This, however, only deepens the mystery. A value detached from a valuer is a deeply strange concept. Values are inherently relational, indexed to the conscious states, intentions, and goals of sentient beings. To posit stance-independent values is to posit an ontological category for which we have no other precedent and no clear explanatory role. Simply asserting that an act is “just wrong” does not explain the ontological status of this wrongness; it merely restates a conviction without providing a metaphysical foundation.
II. The Epistemological Objection: The Argument from Disagreement
Let us, for the sake of argument, grant the existence of this queer realm of objective moral facts. A second, equally severe problem immediately arises: how would we come to know them? Moral realism requires a corresponding moral epistemology, a faculty or method for accessing these stance-independent truths. Yet, unlike in science or mathematics, there is no agreed-upon methodology for discovering moral facts.
Instead, the history of ethics is characterized by profound, persistent, and seemingly intractable disagreement on fundamental principles—not just their application. Deontologists, consequentialists, and virtue ethicists, for example, offer mutually exclusive foundational accounts of morality. This widespread disagreement, which persists even among well-informed and rational interlocutors, is a datum that requires explanation. The moral realist must posit that entire cultures or competing schools of thought are simply mistaken, failing to apprehend the moral truth through a defect in their moral intuition or reasoning.
An anti-realist explanation, however, is far more parsimonious. The diversity of moral beliefs is better explained not by positing a single, objective truth that many somehow fail to see, but by understanding moral codes as evolving social constructs. They are human inventions, shaped by evolutionary pressures, cultural inheritance, and psychological dispositions, designed to solve problems of cooperation and social cohesion. On this view, moral disagreement is not a sign of widespread epistemic failure but the natural result of different communities developing different solutions to shared human problems.
III. A Parity Argument: The Analogy with Aesthetics
To further clarify the anti-realist position, it is useful to draw an analogy with the domain of aesthetic judgment. We do not typically claim that the proposition “chocolate is superior to vanilla” is an objective, stance-independent truth. We recognize that aesthetic preferences are contingent upon a subject’s sensory apparatus, cultural background, and personal history. A claim about taste is only rendered truth-apt when indexed to a particular agent or standard (e.g., “Chocolate is preferable to me”).
The anti-realist argues that moral claims function in a similar manner. They arise from subjective evaluative stances that reflect how actions relate to beings with preferences, values, and goals. To claim that a moral proposition is “objectively true” in a stance-independent sense is to make a category error analogous to claiming that vanilla is objectively inferior. It posits an ontological category—objective value—that behaves unlike any other truth-bearing domain we know.
IV. Ethics After Realism: From Discovery to Construction
A common rejoinder to the anti-realist position is that its acceptance leads inevitably to nihilism or a corrosive relativism where “anything goes.” This objection, however, rests on a false dilemma: either morality is objective in the realist’s sense, or it is entirely arbitrary. We contend that there is a third way: moral constructivism.
Rejecting moral realism does not mean abandoning ethics; it means recognizing ethics as a human project. It frees us from the illusion of moral certainty and compels us to justify our values based on their consequences for human flourishing, their coherence with our considered judgments, and their capacity to win assent in reasoned dialogue. Ethics, on this view, is not a process of discovering pre-existing truths but of creating, negotiating, and revising normative frameworks to govern our shared lives. The foundations of this project are not metaphysical absolutes but shared human needs, empathy, and the pragmatic demands of social cooperation. This understanding makes ethics more flexible, collaborative, and accountable—precisely the features needed for it to adapt to an evolving world.
Conclusion
We have argued that moral realism, despite its intuitive appeal, fails to provide a coherent metaethical account. It succumbs to two decisive objections: the ontological problem of accounting for the nature of moral properties, and the epistemological problem of explaining our access to them in the face of widespread disagreement. The rejection of moral realism, however, is not a loss but a gain for the ethical project. It relieves us of the burden of grounding our ethics in a dubious metaphysics and allows us to focus on the tangible work of building ethical systems grounded in human experience, dialogue, and reason. The absence of an objective moral order is not a void to be feared, but a canvas upon which we have both the freedom and the responsibility to construct a more humane world together.