Moral Realism vs. Anti-Realism

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Journal connection: A recurring sequence contrasts objective and subjective morality, stance-independence, relativism, constructivism, intuition, and the question of whether moral claims can be true or false.
Source boundary: These pages are exploratory argument maps. Use them as routes back to your thinking, not as settled scholarship.
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Distilled Knowledge

Source contribution

Moral realism combines three claims: moral discourse is truth-apt, moral facts or truths are not merely products of an individual’s or culture’s attitudes, and at least some moral claims are true. Anti-realism rejects or revises at least one part of that package through error theory, subjectivism, relativism, or non-cognitivism.

• Ordinary moral discourse and the practice of criticizing entire societies provide realism with an appearance-based case.
• Disagreement, evolutionary genealogy, metaphysical “queerness,” and moral epistemology create serious explanatory burdens for realism.
• Anti-realism may fit a naturalistic ontology more easily but must explain moral error, inference, disagreement, and the authority speakers claim.
• Constructivist and response-dependent approaches complicate a simple objective/subjective binary.

Routes into permanent notes

• Moral Psychology Does Not Settle Metaethics shows why intuition, evolution, and disagreement constrain but do not decide the debate.
• Moral Judgment Argument Map remains usable across multiple metaethical positions.

Evidence boundary

The note is a broad synthesis with numbered claims but no fully visible source apparatus in every section. Check formulations against primary philosophers and current reference works before presenting the taxonomy or historical attributions as definitive.

I. Introduction: Setting the Stage in Metaethics

A. Defining Meta-ethics: The Philosophical Inquiry into Morality Itself

Meta-ethics stands as a fundamental branch of philosophical inquiry, distinguished by its focus not on what is moral, but rather on what morality itself is.1 It delves into the status, foundations, and scope of moral values, properties, and language, seeking to understand the very nature of ethical concepts.1 Unlike normative ethics, which proposes standards of right and wrong action (e.g., “Is euthanasia permissible?”), or applied ethics, which tackles specific moral dilemmas (e.g., “Should this particular patient be allowed to undergo euthanasia?”), metaethics operates at a higher level of abstraction.1 It poses foundational questions such as: What does it mean to say something is “good” or “wrong”? Do moral truths exist independently of human minds? If so, how can we come to know them? These inquiries can be broadly categorized into semantic questions (concerning the meaning of moral terms), ontological questions (concerning the nature and existence of moral properties and judgments), and epistemological questions (concerning the possibility and nature of moral knowledge and justification).2 For instance, a metaethicist might investigate whether the statement “Charity is good” describes an objective feature of the world or merely expresses the speaker’s approval of charity.

The roots of metaethical questioning extend deep into the history of philosophy. Ancient Greek thinkers laid much of the groundwork for these enduring debates. Plato, in dialogues such as the Euthyphro, explored the relationship between divinity and moral value, questioning whether actions are good because God commands them, or if God commands them because they are good—a query that directly probes the source and objectivity of morality.1 Characters in his dialogues, like Callicles in the Gorgias, articulate views akin to moral conventionalism, suggesting that moral distinctions are human inventions rather than natural facts.1 Aristotle, with his teleological ethics centered on eudaimonia (human flourishing), implicitly advanced a form of moral realism by grounding virtue in an objective account of human nature.1 These ancient discussions demonstrate that the core concerns of metaethics are not recent inventions but have been central to philosophical attempts to understand morality for millennia. Indeed, metaethical inquiry often flourishes during periods of significant cultural diversity and intellectual flux, as such times naturally prompt a re-examination of foundational moral beliefs and assumptions.1

The persistence of questions first articulated by ancient philosophers underscores the profound and enduring nature of metaethical concerns. The debates about the source of moral value—whether it resides in divine commands, human conventions, or an objective reality—and the nature of moral language continue to resonate. This stability suggests that the fundamental problems addressed by metaethics, particularly the central debate between moral realism and anti-realism, tap into deep-seated aspects of human moral experience, reasoning, and our attempts to make sense of our place in a world that includes normative dimensions. Consequently, these inquiries remain perennially relevant to the philosophical endeavor.

B. Moral Realism vs. Moral Anti-Realism: The Fundamental Divide

The distinction between moral realism and moral anti-realism represents the most fundamental cleavage within metaethics, addressing the very basis and nature of moral reasoning.6 These two broad positions offer contrasting answers to the core questions about the existence and nature of moral truth.

Moral Realism is the philosophical stance asserting that there are objective moral facts or truths that exist independently of human beliefs, attitudes, feelings, or cultural conventions.6 According to moral realists, when we make moral statements such as “Torture is inherently wrong,” we are attempting to describe a feature of reality. These statements are considered “truth-apt,” meaning they are capable of being objectively true or false.7 Furthermore, moral realists typically hold that at least some of these moral statements are, in fact, true because they accurately correspond to or represent these mind-independent moral realities.8 The wrongness of an act like genocide, for a realist, is not a matter of opinion but an objective moral fact.

Moral Anti-Realism, conversely, encompasses a diverse range of philosophical views united by their denial of the existence of such objective, mind-independent moral facts.6 Anti-realists generally maintain that moral values are, in some crucial sense, subjective, mind-dependent, or constructions of human thought and practice.6 The specific nature of this mind-dependence varies significantly among different anti-realist theories, leading to a wide spectrum of positions under this umbrella.

The dynamic of the debate between realism and anti-realism is significantly shaped by considerations of which stance aligns more closely with common intuitions or, alternatively, which offers a more philosophically parsimonious and defensible account. Moral realism often claims to have “common sense” and the surface grammar of moral language on its side.8 Our ordinary moral discourse frequently involves making claims that appear to assert objective facts (e.g., “It is a fact that kindness is a virtue”).7 This phenomenological appeal can lead realists to suggest that the burden of proof lies with anti-realists to demonstrate why these appearances are deceptive. Anti-realists, however, counter that the metaphysical and epistemological commitments entailed by moral realism are deeply problematic. J.L. Mackie, for instance, famously characterized objective moral properties as “queer” entities, unlike anything else in the universe, and questioned how we could possibly come to know them.14 From this perspective, realism itself bears a substantial explanatory burden to show how such objective values could fit into a naturalistic worldview and how we could gain epistemic access to them. This tension over the “default” position and the locus of the burden of proof fuels much of the ongoing metaethical dialogue.

II. Moral Realism: The Case for Objective Moral Truth

A. Core Tenets: Mind-Independent Moral Facts and Truth-Aptitude

Moral realism is defined by a set of core commitments regarding the nature of morality. These tenets distinguish it sharply from the various forms of anti-realism.

First, there is an ontological commitment: moral realism asserts the existence of moral facts.16 These are not to be understood as mere opinions, personal preferences, or cultural constructs. Instead, they are considered features of reality that exist objectively, meaning their existence and nature are independent of what any particular individual or society thinks, believes, or feels about them.7 For example, if “Lying for personal gain is wrong” is a moral truth, a realist would hold that this is an objective moral fact, akin in its objectivity (though not necessarily in its metaphysical nature) to scientific or mathematical facts.16

Second, there is a semantic commitment, specifically cognitivism: moral statements (e.g., “Stealing is wrong,” “Generosity is a virtue”) are understood as expressing beliefs about these moral facts.7 Because they express beliefs that purport to describe moral reality, these statements are considered “truth-apt”—that is, they are capable of being true or false.7 When an individual utters a moral sentence, the realist interprets this as an attempt to make a factual claim about the moral status of an action, character trait, or state of affairs.

Third, there is an alethic commitment: moral realists maintain that at least some of these truth-apt moral claims are actually true.8 This means that some moral statements successfully correspond to, or accurately represent, the objective moral facts. It is not enough for moral statements to be capable of truth; realism requires that some moral truths are indeed part of the fabric of reality.

These core tenets have significant implications. If moral realism is correct, it provides a solid foundation for objective moral standards by which actions and practices can be judged.7 It allows for the meaningful critique of different moral viewpoints, including those of other cultures or individuals, as potentially objectively mistaken.7 Furthermore, realism supports the idea that moral truths can, at least in principle, be discovered, which can aid in resolving moral dilemmas and disagreements.7 It also offers a robust basis for moral motivation, as individuals would be responding to objective moral requirements rather than arbitrary preferences, potentially imbuing morality with a special normative authority.7 Without such a realist foundation, morality might be seen as lacking a sufficiently strong metaphysical and epistemological footing to support its claims to authority and truth.7

The ontological, semantic, and alethic commitments of moral realism are deeply interconnected. For a moral claim to be objectively true (the alethic commitment), it must be the kind of claim that can be true or false in the first place (the semantic commitment of cognitivism), and there must be some objective moral reality for it to correspond to or describe (the ontological commitment). A successful challenge to any one of these tenets can unravel the entire realist project. For instance, if moral statements are shown not to be truth-apt, as non-cognitivists argue, then the question of their objective truth or correspondence to moral facts becomes moot. Similarly, if one accepts that moral statements are truth-apt but denies the existence of objective moral facts (as error theorists or some subjectivists/relativists do), then moral truth, if it exists at all, cannot be objective in the realist sense. Thus, the coherence and defensibility of moral realism depend on the plausibility of all these intertwined commitments.

B. Historical Trajectory of Moral Realism

The idea that morality is grounded in some form of objective reality has a long and distinguished history, evolving through various philosophical periods and thinkers.

1. Ancient Foundations

The search for an objective basis for ethics is evident in the earliest systematic philosophical inquiries.

• Plato (c. 428/427 – 348/347 BCE) is widely regarded as one of the earliest and most influential proponents of moral realism.1 His metaphysical theory of Forms posits a realm of perfect and eternal archetypes, with the Form of the Good standing as the ultimate, objective source of all reality, truth, and value.17 For Plato, moral knowledge is not derived from sensory experience or convention but is achieved through rational apprehension of these transcendent Forms. Ethics, therefore, is inextricably linked to metaphysics and is independent of, and indeed superior to, theological considerations; God or the gods are good because they align with the Form of the Good, not the other way around.17 The Form of the Good is described as an “unhypothetical first principle” which makes just things genuinely useful and beneficial and is the ultimate aim of human life and the key to eudaimonia (happiness or flourishing).18
  Plato’s grounding of morality in the transcendent Form of the Good provides a powerful account of moral objectivity, suggesting that moral truths are as real and unchanging as mathematical truths. However, this very transcendence introduces significant philosophical challenges. The metaphysical nature of these Forms—their existence separate from the sensible world—and the epistemological question of how human minds can access or gain knowledge of them have been persistent points of debate. These difficulties, in many ways, prefigure later objections to robust forms of moral realism, such as J.L. Mackie’s “argument from queerness,” which questions both the ontological status of objective values and our means of knowing them.14 Thus, while the Platonic vision offers a strong foundation for moral realism, its specific metaphysical commitments have led many subsequent realists to seek alternative, perhaps less ontologically demanding, groundings for moral objectivity.
• Aristotle (384–322 BCE), Plato’s student, is also generally interpreted as a moral realist, though his approach differs significantly.1 Aristotle’s virtue ethics, articulated most famously in the Nicomachean Ethics, grounds morality in an objective account of human nature and the concept of eudaimonia, or human flourishing.4 Virtues (e.g., courage, temperance, justice) are not arbitrary social constructs but are character traits that are objectively good for humans because they are essential for living a well-lived and flourishing human life. This flourishing is achieved by acting in accordance with reason, which is the distinctive function of human beings. Some scholars also identify a “constructivist” element in Aristotle’s ethics, suggesting that moral principles are justified through a deep inquiry into the nature of moral action itself.19 His realism is sometimes characterized as an “internal moral realism,” where moral reality is perceived and understood through phronesis, or practical wisdom—a nuanced intellectual virtue that enables one to discern the right course of action in particular circumstances.19
  The notion of an “internal” moral realism, where access to moral truth is mediated by a cultivated capacity like phronesis 19, presents its own set of complexities. If the perception of moral reality is dependent on possessing a specific, perhaps culturally influenced, perceptual and deliberative capacity, questions arise about the full extent of its objectivity. How does such a view differ from more sophisticated forms of subjectivism or intersubjectivism, where moral truths are only apparent to those individuals who possess the “correct” sensibilities or operate within a particular ethical tradition? This highlights a persistent challenge for moral realists: the need to articulate a plausible epistemology that can support objective moral knowledge without rendering that knowledge either inaccessible to ordinary moral agents or indistinguishable from deeply ingrained subjective or cultural perspectives.

2. Early Modern Rationalism

The 17th and 18th centuries saw the rise of rationalist moral philosophers who, like Plato, believed that moral truths were discoverable through reason and possessed an objective status.

• Samuel Clarke (1675–1729) was a key figure in English rationalism and a staunch defender of moral realism. In works like A Discourse Concerning the Unchangeable Obligations of Natural Religion, Clarke argued that moral obligations arise from the “eternal and necessary differences of things”.20 He maintained that there are inherent “fitnesses” or “unfitnesses” of actions to circumstances, which are discernible by reason, much like mathematical or logical truths.21 For example, given the nature of God as a superior being and humans as dependent creatures, it is inherently “fit” for humans to worship God. These moral relations are objective and self-evident to any rational mind that properly considers them. Crucially, Clarke asserted that these obligations are independent of divine will; God commands certain actions because they are intrinsically good and fit, not the other way around.20 This view of objective, reason-based moral demands was later cited by J.L. Mackie as an example of the kind of “objective prescriptions” that he found metaphysically “queer”.15
  Clarke’s emphasis on self-evident moral truths, apprehended by reason and existing independently of empirical observation or divine decree, establishes a clear intellectual lineage leading to later non-naturalist intuitionist theories, such as those proposed by G.E. Moore and W.D. Ross. Both traditions share a commitment to sui generis moral truths that are grasped through a distinct rational faculty, highlighting a historical continuity in the realist appeal to reason as capable of discerning objective moral principles that are not reducible to natural facts.
• Richard Price (1723–1791), a Welsh philosopher and contemporary of David Hume, was another prominent ethical rationalist and intuitionist.23 In his A Review of the Principal Questions in Morals, Price argued forcefully against empiricist and sentimentalist accounts of morality. He contended that fundamental moral concepts such as “right,” “wrong,” “good,” and “obligation” are simple, unanalyzable ideas grasped directly by the “understanding”—a faculty of reason—rather than being derived from sense experience or emotional responses.24 For Price, moral principles are necessary, eternal, and immutable truths, akin to axioms in geometry, and they become self-evident upon careful reflection.24 He employed “companions in guilt” arguments, suggesting that if one were to deny the possibility of intuitive knowledge of moral truths on empiricist grounds, one would also have to deny such knowledge for other indispensable concepts (like causality or substance) that are similarly not derivable from experience alone.24
  Price’s intuitionism, while robust in its assertion of objective moral truths known through reason, also incorporated a degree of epistemic nuance. He embraced a pluralism of basic duties (e.g., duties to God, self, and others, including beneficence, gratitude, veracity, and justice), acknowledging that these duties could conflict in particular situations.24 Importantly, Price recognized that when these distinct moral considerations are finely balanced, human beings might be unable to determine with absolute certainty what the overall moral truth or the correct course of action is in that specific instance.25 This introduces an element of epistemic humility within the rationalist intuitionist framework. It concedes that even if objective moral truths exist and are, in principle, knowable via reason, our practical access to specific, all-things-considered moral duties can be fallible and limited by the complexity of moral situations and the potential for conflicting obligations. This acknowledgment can be seen as a partial response to arguments from moral disagreement, as it allows for complexity and uncertainty in moral judgment without abandoning the core commitment to moral objectivity.

3. 20th Century and Contemporary Defenses

The 20th century witnessed a resurgence and diversification of moral realist theories, particularly in response to the rise of non-cognitivism and other anti-realist challenges.

• G.E. Moore (1873–1958) is a pivotal figure in the development of 20th-century analytic ethics and a key proponent of non-naturalist moral realism.1 In his seminal work, Principia Ethica (1903), Moore argued that “good” is a simple, unanalyzable, and non-natural property. He famously employed the “Open Question Argument” to demonstrate that “good” cannot be defined in terms of any natural properties (such as pleasure, happiness, or what is desired).8 For any proposed naturalistic definition N of “good” (e.g., “good is pleasure”), Moore contended that it always remains a significant, open question to ask, “Is N (pleasure) itself good?”. If “good” simply meant “pleasure,” this question would be trivial, like asking “Is pleasure pleasure?”. The fact that the question remains meaningful, Moore argued, shows that “good” refers to a distinct, non-natural property, knowledge of which is obtained through a form of rational intuition.27
• W.D. Ross (1877–1971), another influential British philosopher, built upon Moore’s non-naturalism and intuitionism but developed a distinct ethical system.8 In The Right and the Good (1930), Ross rejected Moore’s consequentialist view that right actions are those that maximize good outcomes. Instead, he proposed a pluralistic deontology centered on the concept of prima facie duties.27 These are fundamental, self-evident moral obligations—such as duties of fidelity (keeping promises), reparation (making amends for wrongs), gratitude, justice, beneficence (doing good to others), self-improvement, and non-maleficence (not harming others).28 Ross argued that these duties are “prima facie” in the sense that they are binding at first glance, but they can conflict in particular situations. Our actual duty in any given circumstance is determined by carefully weighing these potentially conflicting prima facie duties through considered judgment, rather than by applying a single, overarching principle.27
  The development from Moore to Ross within early 20th-century intuitionism marks an interesting internal evolution. Moore’s non-naturalism was primarily focused on the indefinable property of “good,” from which he initially derived the concept of “right” in a consequentialist manner.27 Ross, while also a non-naturalist intuitionist, shifted the primary focus of intuition from the property of “goodness” to the direct apprehension of “rightness” as embodied in a plurality of prima facie duties.27 This shift allowed Ross to construct a deontological system that many found more reflective of common-sense moral reasoning, which often involves a direct sense of various distinct obligations (like keeping a promise even if it doesn’t maximize overall good) rather than solely calculating good consequences. This move demonstrated an effort to refine non-naturalist realism to better account for the complexities of moral deliberation and the phenomenology of moral duties, moving away from Moore’s initial, more monistic and consequentialist framework.
• Cornell Realism, which emerged in the latter half of the 20th century, represents a significant movement of moral naturalism. Philosophers associated with this view, such as Richard Boyd, David Brink, Peter Railton, Nicholas Sturgeon, and Geoff Sayre-McCord, argue that moral properties are, in fact, natural properties.1 They contend that moral facts are identical to, or at least supervene upon, complex natural properties, often those studied by the social and biological sciences (e.g., properties related to human flourishing, psychological health, or stable social cooperation).1 Consequently, moral facts are held to be empirically discoverable, much like scientific facts. Cornell Realists often employ a coherentist epistemology, where moral beliefs are justified by their overall coherence with a broader system of beliefs, both moral and non-moral.8 Peter Railton, for instance, famously described his position as a form of “stark, raving Moral Realism,” grounding moral rightness in terms of what would be approved of from an objective, well-informed standpoint.10
• Russ Shafer-Landau is a prominent contemporary philosopher known for his vigorous defense of non-naturalist moral realism.8 He argues that moral facts are objective and irreducible to natural facts, and critically, that science is not the sole arbiter of what exists or what we can legitimately know. Shafer-Landau has also contributed significantly to the debate by offering influential responses to evolutionary debunking arguments against moral realism, which claim that the evolutionary origins of our moral beliefs undermine their claim to objectivity.29
• Other contemporary philosophers who have defended or contributed to moral realist positions include Derek Parfit, whose later work, particularly On What Matters, defended a form of non-naturalist realism focusing on objective reasons 8, and Thomas Scanlon, who advocates for a contractualist ethical theory (“what we owe to each other”) that possesses strong realist elements, grounding morality in principles that no one could reasonably reject.8
  The trajectory of moral realism in the 20th and 21st centuries reveals a dynamic interplay between non-naturalist and naturalist approaches. Following the mid-20th century, during which non-cognitivist theories held considerable sway, the emergence of Cornell Realism marked a powerful revival of moral naturalism. This resurgence was largely motivated by a desire to render moral realism compatible with a broadly scientific and naturalistic worldview, thereby addressing the persistent metaphysical and epistemological “queerness” objections by grounding moral facts firmly within the natural order.7 This trend illustrates the ongoing pressure on moral realism to align its ontological and epistemological commitments with prevailing scientific and metaphysical understandings. It also highlights the increasing diversification within realism itself, as both naturalist and non-naturalist strands continue to evolve, developing sophisticated arguments and responding to new challenges, ensuring that moral realism remains a vibrant and contested position in contemporary metaethics.

C. Varieties of Moral Realism

Moral realism, while united by its core tenets, branches into distinct varieties based on how it conceives the nature of moral facts and properties. The primary division is between moral naturalism and moral non-naturalism.

1. Moral Naturalism

Moral naturalism asserts that moral facts and properties are ultimately natural facts and properties.7 This means they are the kinds of facts and properties that can, in principle, be investigated empirically, similar to those studied in the natural or social sciences (e.g., physics, biology, psychology, sociology). For a moral naturalist, terms like “goodness” or “rightness” might be identified with, or reducible to, complex natural properties such as those that promote human flourishing, maximize happiness, satisfy rational desires, contribute to psychological health, or ensure stable social cooperation.7

The primary motivation for moral naturalism is to reconcile moral realism with a scientific, naturalistic ontology.8 By grounding moral facts in the natural world, naturalists aim to avoid the charge, famously leveled by J.L. Mackie, that objective moral values would be “queer” or metaphysically strange entities, unlike anything else in the universe.14 If moral properties are natural properties, then their existence and our ability to know them become, in principle, no more problematic than the existence and knowability of other natural phenomena. Key proponents of this view include the Cornell Realists, such as Richard Boyd, David Brink, and Peter Railton.1

2. Moral Non-Naturalism (including Intuitionism)

Moral non-naturalism, in contrast, maintains that moral facts and properties, while objective and real, are sui generis—that is, they are of a unique kind and are not reducible to natural (e.g., physical, psychological, biological, or social) facts or properties.7 According to non-naturalists, moral properties like “goodness” or “rightness” are fundamental and irreducible features of reality, distinct from any descriptive, natural properties.7

This view is often, though not exclusively, paired with intuitionism in moral epistemology. Intuitionism holds that fundamental moral truths are self-evident and can be known directly through rational intuition or a distinct moral sense, rather than through empirical observation or logical inference from non-moral premises.25 We apprehend these basic moral truths immediately. Prominent historical proponents of non-naturalist intuitionism include G.E. Moore and W.D. Ross in the 20th century 8, and earlier rationalists like Samuel Clarke and Richard Price, whose emphasis on reason apprehending non-empirical moral truths places them within this broad tradition.20 Contemporary defenders include Russ Shafer-Landau.8

The distinction between moral naturalism and non-naturalism represents a core fault line within the broader camp of moral realism. These two approaches reflect fundamentally different strategies for addressing the primary metaphysical and epistemological challenges that any realist theory must confront. Moral naturalists attempt to demystify moral properties by integrating them fully into the natural world, thereby aiming for compatibility with a scientific ontology and epistemology. This strategy, however, must contend with powerful arguments like G.E. Moore’s Open Question Argument, which questions the possibility of defining moral terms using natural ones 8, and the persistent philosophical puzzle of deriving an “ought” from an “is.” Moral non-naturalists, on the other hand, resolutely uphold the distinctiveness and irreducibility of moral properties. In doing so, they avoid the difficulties of naturalistic reduction but face more acute metaphysical and epistemological challenges, particularly Mackie’s “argument from queerness”.8 This argument presses non-naturalists to explain the nature of these unique, non-natural properties and, crucially, how human beings could possibly come to know them if they are not accessible through ordinary empirical means. Thus, the choice between a naturalist or non-naturalist framework significantly shapes the specific arguments a moral realist will deploy and the particular objections their view will be most vulnerable to. This internal diversity is a testament to the ongoing philosophical efforts to articulate a defensible and comprehensive realist account of morality.

D. Arguments Supporting Moral Realism

Proponents of moral realism advance several arguments to support the claim that objective moral truths exist and can be known.

• Appeals to Moral Experience and Ordinary Language: A significant argument for moral realism is its purported ability to best capture the phenomenology of our moral lives and the way we ordinarily speak and reason about morality.7 When people engage in moral deliberation or debate, they often behave as if there are correct answers to moral questions. Moral judgments frequently appear to express beliefs about objective matters of fact, rather than mere personal preferences or emotions (e.g., “It is true that genocide is wrong,” not just “I disapprove of genocide”).7 The intuitive sense that some actions are simply right or wrong, irrespective of anyone’s opinion, and the ease with which we engage in moral discourse assuming a shared understanding of moral terms, lend prima facie support to realism.16 Ordinary moral thought and talk seem to presuppose a realist framework, which anti-realism must then reject as mistaken or radically reinterpret.7

• Possibility of Moral Knowledge and Progress: Moral realism uniquely allows for the genuine discovery of objective moral truths and, consequently, for the possibility of moral progress.7 If moral truths are objective, then it is possible for individuals or societies to be mistaken about them and, through reflection, experience, or argument, to arrive at a more accurate understanding. This framework makes sense of historical changes, such as the abolition of slavery or the recognition of universal human rights, as instances of genuine moral improvement rather than mere shifts in cultural preference.7 Realism supports the idea that we can possess justified true moral beliefs, which amounts to moral knowledge.16

• Explaining Moral Disagreement: While often cited as an argument against realism, proponents contend that realism offers a better explanation for the nature of genuine moral disagreement.8 When individuals or groups disagree about a moral issue (e.g., the permissibility of capital punishment), they typically believe that the opposing view is mistaken, not simply different. This presupposes that there is a common, objective subject matter about which they are disagreeing and a truth to be found. If moral judgments were merely expressions of preference, as some anti-realists claim, then deep moral disagreements would be more akin to disagreements about taste (e.g., “Chocolate is better than vanilla”) where there is no expectation of one party being objectively correct.

• Explanatory Power (Explanationist Moral Realism): Some contemporary moral realists, particularly within the naturalist camp, argue for the existence of moral facts based on their explanatory power.16 They suggest that moral facts can play a genuine role in explaining various non-moral facts or events. For instance, the moral depravity of a particular regime might be part of the best explanation for its eventual collapse, or the injustice inherent in a social system might best explain widespread social unrest or rebellion. If moral properties can figure in such explanations, this provides an abductive argument for their reality.

• Analogy with Other Domains: Realists sometimes point out that challenges similar to those faced by moral claims—such as persistent disagreement, the difficulty of verification, or the gap between descriptive and prescriptive claims—also exist in other domains where we generally accept the possibility of objective truth, such as psychology, history, or even some areas of the physical sciences.8 The presence of such challenges in morality, therefore, should not automatically lead to the rejection of moral objectivity.

• Epistemological Frameworks: Moral realists have developed various epistemological frameworks to explain how moral knowledge is possible.

• Coherentism: This view, often favored by moral naturalists like David Brink, suggests that moral beliefs are justified if they cohere with a wider set of beliefs, both moral and non-moral, forming a mutually supportive and consistent system.8 Justification is not linear or foundational but holistic.

• Intuitionism/Foundationalism: This approach, characteristic of many non-naturalists like G.E. Moore, W.D. Ross, and Richard Price, holds that certain basic, fundamental moral truths are self-evident and can be known directly through rational intuition, without needing to be inferred from other propositions.8 These intuited truths then serve as the foundation for deriving other, more specific moral judgments.

A significant part of moral realism’s enduring appeal lies in its claim to accurately reflect the experience of making moral judgments and engaging in moral discourse.7 Morality often feels objective; individuals argue and deliberate as if there are right answers to moral questions, and they experience moral obligations as binding, regardless of their personal desires. This powerful and pervasive phenomenology of moral life presents a challenge to anti-realists, who must then bear the burden of explaining why this experience is misleading, illusory, or can be reinterpreted in non-objective terms. The debate, in part, becomes a contest over which metaethical framework offers the most compelling interpretation of our shared moral lives: are they a window onto an objective moral reality, or a complex system of human projections, social conventions, or perhaps useful fictions?

E. Key Challenges and Criticisms

Despite its intuitive appeal and sophisticated defenses, moral realism faces a number of significant challenges and criticisms that have fueled the anti-realist response.

• Moral Disagreement (The Argument from Relativity): One of the oldest and most persistent arguments against moral realism stems from the observation of widespread and often intractable moral disagreement across different cultures, historical periods, and even among individuals within the same society.8 If objective moral truths existed, critics argue, one might expect to see greater convergence in moral beliefs over time, similar to what is observed in the sciences. The persistence of deep moral divisions on issues like abortion, euthanasia, or economic justice is taken by some as evidence that morality is not a domain of objective fact but rather a reflection of differing cultural norms, personal values, or ways of life.15
  Realist Responses: Moral realists offer several counter-arguments. First, they point out that disagreement in a particular domain does not logically entail the absence of objective truth in that domain; for example, there is disagreement in science, history, and even mathematics, yet few would conclude that there are no objective truths in these areas.31 Second, moral disagreements might stem from non-moral factors, such as differing factual beliefs about the consequences of actions, misunderstandings of concepts, or irrationality, rather than fundamental differences in moral values themselves. Third, some apparent moral disagreements might mask underlying agreements on more fundamental moral principles, with differences arising in their application to complex situations.31 Finally, realists may argue that some moral truths are complex and difficult to discern, making disagreement unsurprising, or that some cultures or individuals may simply be mistaken in their moral beliefs.

• Metaphysical Worries (J.L. Mackie’s Argument from Queerness): This is arguably one of the most influential and formidable objections to moral realism, famously articulated by J.L. Mackie in his work Ethics: Inventing Right and Wrong.13 The argument has two prongs:

• Metaphysical Queerness: Mackie argued that if objective moral properties or values existed, they would be entities, qualities, or relations of a “very strange sort, utterly different from anything else in the universe”.13 What makes them “queer” is their supposed inherent prescriptivity or action-guiding nature. An objective good, for instance, would have to have a kind of “to-be-pursuedness” built into it, and an objective wrong would possess an intrinsic “not-to-be-doneness”.14 This contrasts sharply with ordinary natural properties (like shape, size, or mass), which are descriptively inert and do not, in themselves, tell us what to do.14 Mackie often used Plato’s Forms as a dramatic illustration of what such queer objective values might entail.14

• Epistemological Queerness: Correspondingly, Mackie argued that if such metaphysically queer moral properour ordinary ways of knowing everything else”.9 We cannot see, touch, or scientifically measure “wrongness” or “goodness” in the way we perceive physical properties.14 This raises the question of how we could reliably detect these non-natural, intrinsically prescriptive properties.

Realist Responses: Realists have responded to the argument from queerness in various ways.Non-naturalist realists, particularly intuitionists like Moore, Ross, and Price, may embrace the uniqueness of moral properties and argue for the existence of a distinct rational faculty (intuition) capable of apprehending them.27 They might contend that moral properties are indeed different from natural properties, but this distinctness does not make them objectionably “queer” or unknowable.Moral naturalists, on the other hand, attempt to “de-queer” moral properties by identifying them with, or reducing them to, complex natural properties that are metaphysically and epistemologically unproblematic.7 If moral properties are natural properties, then no special faculty is needed to know them; ordinary empirical methods and reasoning would suffice.Some realists argue that the charge of “queerness” is overstated or that other accepted domains of knowledge (e.g., mathematics, logic, consciousness) also involve entities or properties with unusual features, so morality is not uniquely problematic in this regard. They might also challenge Mackie’s assumption that objective values must be intrinsically and overridingly motivating in the way he describes.

• Compatibility with Naturalism (and the “Is-Ought” Problem / Naturalistic Fallacy): A persistent challenge for moral realism, especially for its non-naturalist variants, is its compatibility with a broadly naturalistic worldview, which tends to be skeptical of entities or properties that are not amenable to scientific investigation or part of the natural causal order.8

• G.E. Moore’s Open Question Argument (OQA): As discussed earlier, Moore used the OQA to argue that “good” cannot be defined in terms of any natural property, because for any proposed natural property N, it always remains a meaningful, open question to ask whether N is, in fact, good.8 This poses a direct challenge to moral naturalism’s attempt to reduce moral properties to natural ones.

• Hume’s “Is-Ought” Problem: David Hume famously observed that there appears to be a logical gap between descriptive statements about what is the case (facts) and prescriptive or normative statements about what ought to be the case (values or obligations).8 It seems impossible to validly deduce an “ought” conclusion from purely “is” premises. This challenges naturalist attempts to derive moral obligations directly from observations about the natural world.

Realist Responses:Non-naturalists often accept that moral facts are indeed non-natural and argue that a naturalistic worldview is overly restrictive; science is not the sole path to knowledge or the only arbiter of what is real.8 They might contend that “ought” statements are grounded in these distinct, non-natural moral facts, apprehended through reason or intuition.Naturalists, conversely, must try to bridge the “is-ought” gap. Some argue that moral properties are natural properties, or supervene on them in a way that grounds normativity. They might challenge the conclusiveness of Moore’s OQA, for example, by drawing analogies to scientific identities (like “water is H₂O”) which are true even if not semantically obvious from the concepts alone.8 Other naturalists might argue that certain natural facts (e.g., facts about human needs or flourishing) inherently possess normative implications, or that moral concepts themselves have a functional role that connects them to natural facts. Some realists also argue that certain moral facts inherently contain prescriptive elements, thus blurring the sharp “is-ought” distinction.16

• Psychological Concerns (Motivation): The relationship between moral judgment and motivation is another contentious area.8 The debate often revolves around motivational internalism (the view that there is a necessary, internal connection between making a moral judgment and being motivated to act accordingly) versus motivational externalism (the view that any connection is contingent and external, requiring a separate desire or disposition).

• Argument against Realism: If moral judgments are, as realists claim, beliefs about objective facts, and if beliefs (as some philosophers argue) are motivationally inert (i.e., they cannot by themselves move someone to act without being coupled with a desire), then how can moral judgments reliably motivate action? Non-cognitivists often leverage this point, arguing that the inherent motivational force of morality suggests that moral judgments are more akin to desires, emotions, or commitments (which are intrinsically motivating) rather than purely cognitive beliefs about facts.8

• Realist Responses: Realists offer several lines of reply. Some realists, known as moral judgment internalists, argue that moral beliefs can be intrinsically motivating, or that they necessarily entail certain motivations.8 They might point to other beliefs, like the belief that one is in pain, which also seem to carry inherent motivational force. Other realists adopt moral judgment externalism, denying a necessary connection between moral judgment and motivation.8 They can explain motivational failures by appealing to factors such as weakness of will (akrasia), depression, emotional interference, or even sheer perversity or evil, without this undermining the truth of the moral judgment itself or the sincerity of the agent’s belief. Some realists, like Michael Smith, propose a conceptual connection not directly to motivation, but between moral rightness and reasons for action, suggesting that if an action is morally right, there is necessarily a reason for any rational agent to perform it, even if that agent is not, in fact, motivated to do so.8

• Evolutionary Debunking Arguments (EDAs): In recent decades, EDAs have posed a significant challenge to moral realism.13 The core of these arguments is that our moral beliefs and faculties are primarily the product of evolutionary processes (natural selection) that have shaped us to hold beliefs and exhibit behaviors conducive to survival and reproduction, rather than to accurately track mind-independent moral truths.33 If our moral psychology can be largely or entirely explained by these evolutionary pressures without any need to posit the existence of objective moral facts that our beliefs correspond to, then our confidence in the objectivity of those moral beliefs is undermined. The argument often takes the form: (P1) Our moral beliefs are heavily influenced by evolutionary forces. (P2) Evolutionary forces aim at enhancing reproductive fitness, not at tracking objective truth (especially non-natural truth). (P3) Therefore, there is no good reason to think that our evolved moral beliefs reliably track objective moral truths, even if such truths were to exist. (C) Consequently, our moral beliefs lack justification if moral realism is true, or at least their justification is severely undercut.33
  Realist Responses (e.g., advanced by philosophers like Russ Shafer-Landau, David Enoch, Peter Singer, and others):
  One common response is the Third-Factor Reply or appeal to a Pre-established Harmony: Evolution might have selected for beliefs, dispositions, or behaviors (e.g., altruism towards kin, cooperation, fairness) that happen to align with or reliably track objective moral truths, precisely because those moral truths themselves concern matters like well-being, successful social living, or harm reduction, which are also relevant to reproductive fitness.
  Another line of defense argues for the Immunity of Certain Moral Beliefs or the Role of Rational Reflection: Some core moral beliefs, or our capacity for abstract rational moral reflection, might be less directly influenced by specific evolutionary pressures, or human reason might allow us to transcend, correct, or critically assess our more primitive, evolved moral intuitions.29 Our capacity for rationality, it is argued, extends far beyond its immediate evolutionary utility and can be applied to discern moral truths.36
  Some realists charge that EDAs commit the Genetic Fallacy: the fallacy of assuming that the origin of a belief determines its epistemic justification.33 Even if our moral beliefs have an evolutionary origin, their justification must be assessed based on the current evidence and reasons we have for holding them, not merely on how we came to have them.
  It has also been argued that EDAs might be Self-Defeating: if the evolutionary origins of our moral beliefs undermine their justification, then similar arguments might be constructed to undermine our belief in the theory of evolution itself, or the reliability of our other cognitive faculties (including those used to formulate EDAs), if they too are products of evolution.
  Non-Naturalist Defense: Some non-naturalist realists, like Derek Parfit and Peter Singer, argue that EDAs primarily target naturalistic forms of moral realism. They contend that our capacity for highly abstract moral reasoning (e.g., grasping complex utilitarian principles or universal rights) cannot be fully explained by evolutionary pressures geared towards immediate survival or kin selection, potentially strengthening the case for non-natural, rationally accessible moral truths.33

J.L. Mackie’s Argument from Queerness serves as a powerful and influential synthesis of many of the core challenges to moral realism.13 Its metaphysical prong directly questions the ontological status of objective moral facts, asking what kind of strange things these intrinsically prescriptive entities would be. This connects to broader concerns about naturalism, parsimony, and the compatibility of such entities with a scientific worldview. Its epistemological prong questions our cognitive access to these purported facts, asking how we could possibly come to know such queer things if they are not detectable by ordinary empirical means. This links to issues of persistent moral disagreement and the apparent need for special, perhaps mysterious, epistemic faculties. A significant portion of subsequent metaethical theorizing, from both realist and anti-realist perspectives, can be understood as attempting to respond to, accommodate, or build upon the profound challenges posed by Mackie’s “queerness” argument.

Evolutionary Debunking Arguments have also significantly shaped the contemporary metaethical landscape. Initially, EDAs posed a formidable threat to moral realism by suggesting that our moral intuitions are unreliable products of adaptive processes geared towards fitness rather than truth.33 However, realist responses have grown in sophistication, challenging various premises of the debunking arguments.29 These responses often question the directness and pervasiveness of evolutionary influence on all moral beliefs, highlight the crucial role of rational reflection in refining or even overriding evolved intuitions, or argue that evolution might have, perhaps coincidentally or through a third factor, led us towards moral truths. The debate now often centers on complex issues such as whether objective moral truth is a necessary part of the best explanation for the content of our moral beliefs, or whether purely naturalistic evolutionary explanations (which do not invoke moral truth) suffice. EDAs have compelled moral realists to develop more nuanced epistemologies that can account for the evolutionary origins of some aspects of our moral psychology while still defending the potential for our moral beliefs to be justified and to track objective moral truths. This has pushed the discussion beyond simplistic claims of unreliability to more intricate considerations of explanatory power, the scope of rational assessment, and the relationship between biology and normativity.

III. Moral Anti-Realism: Challenging Objective Morality

A. Core Tenets: The Rejection of Mind-Independent Moral Facts

Moral anti-realism stands in direct opposition to moral realism. Its fundamental characteristic is the denial of the central ontological claim of realism: that moral properties, facts, values, or relations exist objectively and independently of human minds, attitudes, beliefs, or social conventions.7 Anti-realism is not a single, monolithic doctrine but rather a broad family of diverse philosophical positions.13 These various views are united in what morality is not—namely, a domain of objective, mind-independent facts—but they differ significantly in their positive accounts of what morality is (e.g., expressions of emotion, disguised commands, social constructs, systematically false claims about a non-existent reality, or useful fictions).

The denial of objective moral facts, which is the hallmark of anti-realism, can manifest in two principal ways.13 First, some anti-realist theories deny that moral properties exist at all. This is the stance taken by non-cognitivist theories, which argue that moral language does not even attempt to describe reality, and by moral error theory, which argues that moral language does attempt to describe an objective moral reality, but that such a reality does not exist, rendering all such claims false. Second, other anti-realist theories accept that moral properties or truths can exist but assert that their existence is, in some crucial sense, mind-dependent or non-objective. This is the approach taken by various forms of moral subjectivism and moral relativism, where moral values are seen as contingent upon individual or cultural perspectives.13

The common thread uniting all forms of moral anti-realism is this rejection of the realist’s ontological thesis concerning mind-independent moral facts.10 Beyond this shared denial, anti-realist theories offer a wide array of positive accounts regarding the nature, function, and status of moral language, moral judgment, and moral practice. This internal diversity means that arguments which may be effective against one particular form of anti-realism (e.g., simple subjectivism) might not apply to, or be as potent against, other, more sophisticated versions (e.g., quasi-realism or certain forms of constructivism). Therefore, a thorough understanding of moral anti-realism requires careful attention to the specific claims, arguments, and nuances of its distinct sub-theories, rather than treating it as a single, undifferentiated opponent to moral realism.

B. Historical Trajectory of Moral Anti-Realism

Challenges to the idea of objective morality are as ancient as philosophy itself, with various thinkers across history expressing skeptical, relativistic, or subjectivist views.

1. Ancient Skepticism and Relativism

In ancient Greece, the Sophists were among the first to articulate views that can be interpreted as anti-realist. Protagoras’s famous dictum, “Man is the measure of all things,” is often cited as an early expression of relativistic or subjectivist ideas, suggesting that truth, including moral truth, might be relative to human perception or convention.31 Thrasymachus, as depicted in Plato’s Republic, notoriously argued that justice is nothing more than “the advantage of the stronger,” a position that can be seen as a form of moral nihilism (denying the existence of genuine moral values) or a cynical form of conventionalism where moral language is merely a tool of power.1 Beyond these specific doctrines, ancient Greek philosophy also saw currents of moral skepticism, which questioned the possibility of attaining certain moral knowledge, even if they did not always fully embrace relativism about moral truth itself.31 These early questionings laid the groundwork for later, more systematic anti-realist theories.

2. Early Modern Precursors

The early modern period saw further development of ideas that challenged objective moral realism, often by grounding morality in human nature, desires, or social agreements rather than transcendent principles.

• Thomas Hobbes (1588-1679), in his work Leviathan, argued that in the “state of nature”—a hypothetical condition without government or social rules—concepts like justice and injustice, right and wrong, have no place. For Hobbes, moral principles are essentially rules of prudence or “articles of peace” that rational individuals agree upon for their mutual advantage, primarily to escape the “war of all against all” and to achieve security and peaceful social co-existence.39 This implies that the basis of morality is utility and human agreement rather than objective, pre-social rightness or wrongness.
• Baruch Spinoza (1632-1677), in his Ethics, explicitly denied that things are good or bad in themselves, independently of human desires and beliefs.41 He argued that we judge something to be good because we desire it; we do not desire it because it is intrinsically good. Moral terms like “good” and “evil” are, for Spinoza, relative to human perspectives, needs, and utility, rather than indicating inherent properties of things in the world.41
• David Hume (1711–1776) is a pivotal figure whose moral philosophy, particularly his sentimentalism, laid crucial groundwork for many subsequent anti-realist theories.1 In A Treatise of Human Nature and An Enquiry Concerning the Principles of Morals, Hume famously argued that moral distinctions are not derived from reason but from sentiment or feeling.32 Specifically, moral judgments arise from feelings of approval (approbation) or disapproval (disapprobation) that we experience when contemplating characters or actions, often through the mechanism of sympathy with others.32 His influential observation that one cannot logically derive an “ought” (a prescriptive moral judgment) from purely “is” premises (descriptive factual statements) further challenged the idea that morality could be grounded in objective facts about the world.32 While Hume’s precise metaethical classification remains a subject of scholarly debate—with interpretations ranging from subjectivism to a sophisticated form of intersubjectivism, and his work being foundational for later non-cognitivism—his arguments strongly pointed away from rationalist moral realism and emphasized the role of human psychology and emotion in the constitution of morality.42
  Hume’s legacy for anti-realism is complex and multifaceted. His powerful emphasis on sentiment as the source of moral judgment directly inspired later emotivist and expressivist theories, which view moral language as primarily serving to express feelings or attitudes rather than to state facts.32 However, Hume also sought to explain the apparent stability and commonality of moral judgments by appealing to universal features of human nature, such as sympathy, and the notion of adopting a “common point of view” or the perspective of an “impartial spectator” when making moral evaluations.32 This aspect of his thought suggests an attempt to secure a kind of objectivity or at least intersubjectivity for moral judgments, preventing them from being purely idiosyncratic or arbitrary. This complexity makes Hume a rich source for various anti-realist interpretations. His philosophy powerfully illustrates that the path away from robust, mind-independent moral realism does not necessarily lead to simple subjectivism; rather, it opens up conceptual space for more nuanced accounts that endeavor to explain the shared, stable, and seemingly objective features of moral practice without committing to the metaphysical and epistemological claims of traditional realism.

3. 20th Century and Contemporary Articulations

The 20th century marked a significant flourishing of anti-realist thought, partly spurred by developments in other areas of philosophy, particularly the philosophy of language and epistemology.

The rise of logical positivism in the early 20th century, with its verificationist theory of meaning (the principle that a non-analytic statement is meaningful if and only if it is empirically verifiable), provided a strong impetus for non-cognitivist theories of ethics.1 Since moral statements (e.g., “Murder is wrong”) do not seem to be empirically verifiable in the way scientific statements are, nor are they analytic truths (true by definition), logical positivists often concluded that they were literally meaningless from a factual standpoint, or at best, served a non-descriptive function, such as expressing emotions.

Throughout the 20th century and into the 21st, moral anti-realism diversified considerably. More sophisticated versions of non-cognitivism emerged, including R.M. Hare’s prescriptivism, and later, the expressivist projects of Simon Blackburn (quasi-realism) and Allan Gibbard (norm-expressivism).1 Concurrently, moral error theory, most famously articulated by J.L. Mackie, offered a cognitivist but anti-realist alternative, arguing that moral judgments are truth-apt but systematically false.1 Debates around moral subjectivism and moral relativism also continued, with philosophers developing more refined versions of these views. More recently, proposals like moral fictionalism have gained attention, suggesting a way to live with the conclusions of error theory without abandoning moral discourse entirely.13 This ongoing development and diversification underscore the vitality of anti-realist approaches in contemporary metaethics.

C. Principal Forms of Moral Anti-Realism

Moral anti-realism is not a single theory but a collection of distinct positions that share the rejection of objective, mind-independent moral facts. These theories offer different accounts of what moral language and moral judgments are, if they are not descriptions of an objective moral reality.

1. Non-Cognitivism

Non-cognitivism is a broad category of metaethical theories holding that the primary function of moral statements is not to express propositions or beliefs that are capable of being true or false (i.e., moral statements are not truth-apt).7 Instead, their principal linguistic role is non-descriptive. Moral utterances serve to express emotions, attitudes, preferences, or to issue commands, prescribe actions, or influence the behavior of others.

• a. Emotivism: This theory, prominent in the early to mid-20th century, argues that moral statements are fundamentally expressions of emotion or sentiment, or serve to evoke similar emotions in others.7 According to emotivism, saying “Murder is wrong” is not stating a fact about murder but is more akin to exclaiming “Murder, boo!” or expressing one’s strong disapproval of murder and perhaps trying to get others to share that disapproval.7

• Key Proponents:

• A.J. Ayer (1910–1989): Heavily influenced by logical positivism and its verification principle, Ayer, in Language, Truth and Logic (1936), argued that ethical statements are “pseudo-concepts” or “ejaculations”.1 Since they are neither analytic truths nor empirically verifiable, they lack literal or factual meaning. Their function is purely emotive: to express the speaker’s feelings and to arouse feelings or stimulate action in the hearer.44 For Ayer, when one says “Stealing money is wrong,” the predicate “…is wrong” adds no factual content; it merely evinces moral disapproval.13

• C.L. Stevenson (1908–1979): Stevenson offered a more nuanced version of emotivism in works like Ethics and Language (1944). While agreeing with Ayer that moral terms have an emotive meaning (expressing the speaker’s attitudes and aiming to influence the attitudes of others), Stevenson also acknowledged a descriptive component to moral language.1 He emphasized the “dynamic” or “quasi-imperative” force of moral terms, designed to redirect the listener’s attitudes and behavior.49 Stevenson also focused on the nature of moral disagreement, distinguishing between “disagreement in belief” (about facts) and “disagreement in attitude” (about what to prefer or approve of), arguing that moral disputes often involve the latter.51

• Criticisms of Emotivism:

• The Frege-Geach Problem (Embedding Problem): This is a major challenge for many forms of non-cognitivism, including emotivism.16 The problem arises because moral terms appear not only in simple assertions (e.g., “Lying is wrong”) but also in unasserted contexts, such as conditionals (“If lying is wrong, then getting your little brother to lie is wrong”), negations (“Lying is not wrong”), questions (“Is lying wrong?”), or propositional attitude reports (“Fred believes that lying is wrong”).52 If the meaning of “lying is wrong” is simply an expression of disapproval (e.g., “Boo to lying!”), it’s unclear how it retains a consistent meaning or logical function in these embedded contexts where no disapproval is being directly expressed. For instance, in “If lying is wrong…”, the speaker is not booing lying. This makes it difficult for emotivism to explain the validity of moral arguments that use such complex sentences, as the moral terms seem to equivocate.52

• Problem of Moral Reasoning and Disagreement: Early forms of emotivism were criticized for making moral reasoning seem impossible or irrational. If moral judgments are just expressions of feeling, how can we rationally argue about them? How can there be genuine moral disagreement beyond a mere clash of emotions?.45 Stevenson’s notion of “disagreement in attitude” was an attempt to address this, but critics questioned if it fully captured the nature of moral disputes, which often seem to involve more than just conflicting feelings.

• Trivialization of Morality: Critics argued that emotivism trivializes morality by reducing it to mere emotional outbursts, failing to account for the seriousness and perceived objectivity of moral convictions and obligations.

The Frege-Geach problem, in particular, has been a persistent and powerful challenge for non-cognitivist theories. It highlights a fundamental difficulty: if the meaning of moral terms is tied to a specific speech act (like expressing an emotion or issuing a command), then how can these terms function consistently across different linguistic contexts, especially in logical inferences where they appear in unasserted clauses (e.g., the antecedent of a conditional)? If the meaning shifts, then logical arguments involving moral terms would seem to commit fallacies of equivocation. This has spurred non-cognitivists to develop more sophisticated semantic theories to account for the logical behavior of moral language.

• b. Prescriptivism: This non-cognitivist theory, most notably developed by R.M. Hare, views moral statements primarily as universalizable imperatives or commands.7 When someone says an action is morally wrong, they are, according to prescriptivism, effectively saying “Do not do that action” and are, crucially, willing to universalize this command to all relevantly similar situations, including those involving themselves.

• R.M. Hare (1919–2002): In works like The Language of Morals (1952) and Freedom and Reason (1963), Hare argued that the central function of moral judgments is to guide action.49 Moral language has a prescriptive meaning, meaning it entails an imperative.54 A key feature of moral prescriptions, distinguishing them from other kinds of imperatives (like simple orders), is their universalizability.49 If I say “You ought not to lie in this situation,” I am committed to the view that anyone (including myself) ought not to lie in any relevantly similar situation.54 Hare believed that this logical feature of moral language provided a basis for rational moral reasoning, even within a non-cognitivist framework, as it forces consistency in moral judgments.1

• Criticisms of Prescriptivism: Critics have questioned whether all moral judgments can be adequately translated into imperatives or commands. For example, judgments about the moral character of historical figures or about states of affairs that no one can control seem difficult to frame as prescriptions. Furthermore, while universalizability is an important feature of much moral reasoning, it is debated whether it is sufficient to capture the full content of morality or to distinguish genuinely moral prescriptions from non-moral ones (e.g., aesthetic or prudential universalizable prescriptions). There are also concerns about whether prescriptivism can fully account for the motivational force of moral judgments or the nature of moral weakness.

• c. Quasi-Realism (Expressivism): This is a more contemporary and sophisticated form of non-cognitivism, most prominently associated with Simon Blackburn. Quasi-realism starts from an expressivist base—the idea that moral judgments express non-cognitive attitudes or states of mind (like approval, disapproval, or commitment to norms)—but it aims to explain and justify why moral language has many of the surface features of realist discourse.1 Quasi-realists argue that we can legitimately talk about moral truth, moral facts, moral knowledge, and the validity of moral arguments, even though, at a fundamental metaethical level, there are no objective, mind-independent moral properties that these statements describe.56

• Simon Blackburn (1944–Present): Blackburn’s project is to show how a non-cognitivist can “earn the right” to use the apparently realist language of morals.1 He argues that our practice of making moral judgments involves projecting our attitudes onto the world as if they were objective properties.56 The quasi-realist then seeks to construct an account of how these projected attitudes can mimic the logical structure and inferential patterns of realist discourse. For example, to address the Frege-Geach problem, Blackburn suggests that complex moral sentences (like conditionals) express higher-order attitudes towards combinations of first-order attitudes.57 So, “If lying is wrong, then getting your little brother to lie is wrong” might express approval of having a negative attitude towards getting one’s brother to lie, conditional on having a negative attitude towards lying itself.

• Criticisms of Quasi-Realism: One major line of criticism is whether quasi-realism is ultimately distinguishable from either a very sophisticated form of subjectivism or a subtle form of moral fictionalism. Critics question whether it genuinely succeeds in earning the realist-sounding language without covertly relying on realist commitments, or if it is, as some have put it, just “error theory in sheep’s clothing” trying to make us feel better about the lack of objective values. There are also concerns about whether quasi-realism can fully account for the robust phenomenology of moral conviction and the sense that moral demands are genuinely binding, rather than just projections of our attitudes.

The project of quasi-realism often faces the challenge of “having its cake and eating it too.” It attempts to capture all the desirable features of realist moral discourse (objectivity-talk, truth-aptness, logical reasoning) while maintaining an underlying anti-realist metaphysics (no objective moral facts). This delicate balancing act makes the theory intellectually intriguing but also vulnerable to criticisms from both realist and other anti-realist camps, questioning its ultimate coherence or stability.

• d. Norm-Expressivism: This view, closely associated with Allan Gibbard, is another contemporary form of expressivism. It holds that moral judgments, and more broadly normative judgments (including judgments about what is rational), express the acceptance of systems of norms that govern action, thought, and feeling.1

• Allan Gibbard (1942–Present): In works like Wise Choices, Apt Feelings (1990), Gibbard argues that the primary function of normative language, including moral language, is to facilitate social cooperation and coordinate behavior by expressing commitment to shared norms.1 To judge an action as morally right is to express one’s acceptance of a system of norms that permits or requires that action. Similarly, to call an action rational is to express one’s acceptance of norms for thought or action that endorse it.58 Gibbard’s theory attempts to provide a naturalistic account of normativity, rooted in human psychology and social needs.

• Criticisms of Norm-Expressivism: Like quasi-realism, norm-expressivism faces challenges in fully explaining the apparent objectivity and binding force of moral demands, especially when an individual’s accepted norms conflict with deeply held moral intuitions or the norms of others. If norms are ultimately grounded in acceptance, the question arises as to what makes one set of norms more valid or authoritative than another. There are also ongoing debates about how successfully norm-expressivism addresses semantic challenges like the Frege-Geach problem.

2. Moral Error Theory (Moral Nihilism)

Moral error theory is a cognitivist but anti-realist view.8 It agrees with moral realism that moral statements are truth-apt—that is, they purport to describe objective moral facts and express beliefs about them. However, error theory diverges from realism by asserting that all such positive moral claims (e.g., “X is morally good,” “Y is morally obligatory”) are systematically false.1 This is because, according to the error theorist, the objective moral properties or facts that these statements presuppose simply do not exist.13 In this sense, morality, as commonly understood, is a kind of widespread, institutionalized mistake or illusion. While sometimes equated with moral nihilism, error theory is more specific: nihilism might broadly deny moral values, whereas error theory makes a specific claim about the truth-value of our moral judgments.

• J.L. Mackie (1917–1981): Mackie is the most prominent modern proponent of moral error theory, coining the term and defending the view in his influential book Ethics: Inventing Right and Wrong (1977).1 Mackie’s argument for error theory rests primarily on two claims:

• The Argument from Relativity (or Disagreement): Mackie pointed to the wide variations in moral codes from one society to another and from one historical period to another.13 He argued that this radical diversity is better explained by the hypothesis that moral codes reflect different ways of life and social conventions rather than by the hypothesis that they are imperfect perceptions of objective moral truths.15

• The Argument from Queerness: This is Mackie’s central argument.13 As discussed previously, it has two components:

• Metaphysical Queerness: Objective values, if they existed, would be entities or qualities of a very strange sort, utterly different from anything else in the universe. They would have to be intrinsically prescriptive or action-guiding—possessing what Mackie called “objective prescriptivity” or an inherent “to-be-doneness” or “not-to-be-doneness”.14 Mackie found such properties to be ontologically bizarre and incompatible with a naturalistic, scientific worldview.15

• Epistemological Queerness: If such queer objective values existed, our knowledge of them would require some special faculty of moral perception or intuition, entirely different from our ordinary ways of knowing everything else.14 Mackie was skeptical about the existence of such a faculty.

• Arguments for Error Theory: The core argument is that ordinary moral discourse is deeply committed to the existence of objective, categorical imperatives—moral demands that apply to agents irrespective of their desires or ends.15 However, Mackie argues, such objective, intrinsically prescriptive entities do not fit into a plausible naturalistic ontology. Therefore, since our moral language presupposes something that does not exist, our positive moral judgments are systematically false.

• Criticisms of Error Theory:

• Radical Counter-Intuitiveness: Error theory leads to the conclusion that statements like “Torturing innocent children for fun is wrong” are false. This strikes many as deeply counter-intuitive and morally repugnant.

• Practical Implications: If all moral judgments are false, what are the practical consequences for how we should live or organize society? Does it lead to moral apathy, amoralism, or social chaos? This is often called the “now what?” problem.46

• Undermining Normative Discourse: If moral claims are all false, it seems to undermine the possibility of meaningful moral deliberation, critique, and justification.

The implications of moral error theory are profound. If it is true, it requires a radical revision of our understanding of morality and potentially of our moral practices. It suggests that the entire edifice of moral thought and language, which plays such a central role in human life, is founded upon a fundamental error about the nature of reality. This makes the “now what?” question particularly pressing for error theorists.

3. Moral Subjectivism (Individual Relativism)

Moral subjectivism is the metaethical view that moral truths are dependent on the attitudes, beliefs, or feelings of individuals.3 In its simplest form, when someone states “X is morally wrong,” they are essentially reporting or expressing their personal disapproval of X. Similarly, “X is morally right” would mean “I approve of X.” Thus, the truth or falsity of moral propositions is determined by the individual’s own subjective states.43 It is a form of cognitivism because ethical sentences express propositions that can be true or false, but these truth-values are relative to the individual.43

• Arguments for Moral Subjectivism:

• Accounts for Individual Differences: Subjectivism readily explains the wide variation in moral judgments among individuals, even within the same culture.

• Emphasizes Individual Autonomy: It aligns with a strong sense of individual autonomy in moral matters, suggesting that each person is the ultimate arbiter of their own moral code.

• Avoids Problems of Cultural Relativism: It sidesteps the difficulty of defining “culture” or determining which societal norms apply to individuals belonging to multiple groups, as the locus of moral truth is the individual.40

• Criticisms of Moral Subjectivism:

• Makes Moral Disagreement Incomprehensible: If moral statements are merely reports of individual feelings or attitudes, then genuine moral disagreement seems impossible.31 If I say “Abortion is wrong” (meaning I disapprove of abortion) and you say “Abortion is not wrong” (meaning you do not disapprove of abortion), we are both making true statements about our respective feelings. There is no contradiction and no basis for rational debate about the morality of abortion itself.

• Implies Moral Infallibility: Subjectivism seems to imply that individuals are infallible in their moral judgments.31 If “X is right” just means “I approve of X,” then as long as I genuinely approve of X, my judgment that X is right cannot be mistaken. This contradicts the common experience of changing one’s mind about moral issues or recognizing past moral errors.

• Fails to Capture the Normative Force of Morality: Morality seems to involve more than just personal preferences; it typically carries a sense of obligation or “oughtness.” Subjectivism struggles to account for this normative dimension. If “Stealing is wrong” only means “I disapprove of stealing,” it doesn’t explain why others (or even myself at a later time) ought not to steal.

• Implies “Anything Goes”: A common and serious objection is that subjectivism leads to the conclusion that any action can be morally permissible as long as some individual approves of it.31 This would mean that even horrific acts could be deemed “morally right” for the person performing them, if that person genuinely holds that belief or attitude.

The challenge of explaining genuine moral disagreement is particularly acute for simple subjectivism. If morality is purely a matter of personal taste or feeling, then our deeply held moral convictions and the passionate debates that surround them appear to be fundamentally misguided or based on a misunderstanding of what we are actually doing when we make moral claims. This failure to account for the interpersonal and apparently objective features of moral discourse leads many to find subjectivism an unsatisfactory metaethical theory.

4. Moral Relativism (Cultural Relativism)

Moral relativism, often specifically cultural relativism, posits that moral truths are not absolute or universal but are relative to the conventions, practices, values, or agreements of a particular culture or society.3 According to this view, a moral judgment like “Polygamy is wrong” is true or false depending on the accepted norms of the society in question. If a society’s norms permit polygamy, then it is morally permissible within that society; if another society’s norms condemn it, then it is morally wrong within that society. There is no overarching, transcultural standard by which to judge one society’s norms as objectively superior to another’s.31 Like subjectivism, it is a cognitivist position, as moral statements are truth-apt, but their truth is relative.43

• Arguments for Moral Relativism:

• Explains Cultural Diversity: The most common argument for cultural relativism is the empirical observation of vast diversity in moral beliefs and practices across different cultures and historical periods.11 Relativism offers a straightforward explanation: these differences arise because morality itself is culturally determined.

• Promotes Tolerance: It is often argued that recognizing the relative validity of different moral codes can foster tolerance and respect for other cultures, discouraging ethnocentrism (the belief that one’s own culture’s values are superior).31

• Key Proponents: Historically, cultural relativism has been strongly associated with anthropologists such as William Graham Sumner and Ruth Benedict, who documented extensive cultural variation in moral practices.31 Contemporary philosophical defenders of more sophisticated forms of moral relativism include Gilbert Harman and David B. Wong.1

• Criticisms of Moral Relativism:

• Problem of Defining “Culture” or “Society”: Relativism faces the difficulty of clearly and unambiguously defining the relevant “culture” or “society” to which moral truth is relative. Individuals often belong to multiple subcultures (national, religious, professional, familial), which may have conflicting norms. Which group’s standards take precedence?

• Impossibility of Cross-Cultural Moral Critique: If moral truth is entirely relative to cultural norms, then it becomes impossible or illegitimate to morally criticize the practices of other cultures, no matter how abhorrent they may seem from an external perspective (e.g., genocide, institutionalized oppression).31 It also makes it difficult to criticize the norms of one’s own society.

• Inability to Account for Moral Progress (The Reformer’s Dilemma): Cultural relativism struggles to make sense of the concept of moral progress within a society.31 If “right” is simply what a society currently approves of, then any moral reformer who challenges those prevailing norms (e.g., those who fought against slavery or for women’s suffrage) would, by definition, be acting “wrongly” according to their society’s standards at that time. This makes it hard to see how societies can morally improve.

• Inconsistent Argument for Tolerance: The claim that relativism promotes tolerance can be inconsistent.31 If tolerance is itself presented as a universal moral value that all cultures should adopt, this contradicts the core relativist thesis that there are no universal moral values. If tolerance is merely a value specific to certain cultures, then cultures that do not value tolerance have no moral reason, on relativist grounds, to be tolerant.

• Implies Repugnant Practices Can Be “Right”: Perhaps the most damaging criticism is that cultural relativism seems to imply that even morally horrific practices (e.g., slavery, honor killings, female genital mutilation) could be considered “morally right” if they are sanctioned by the norms of a particular culture.31 This clashes strongly with the intuition that some actions are wrong regardless of cultural acceptance.

The “reformer’s dilemma” poses a particularly sharp challenge to cultural relativism. If morality is strictly defined by existing societal standards, then individuals like Martin Luther King Jr., Mahatma Gandhi, or Nelson Mandela, who challenged the prevailing moral norms of their societies, would have been morally wrong according to those standards. Yet, many view these figures as moral heroes who brought about positive moral change. Cultural relativism seems unable to account for this kind of moral progress driven by internal critique and reform, as it lacks a standard independent of current societal approval by which to judge such changes as improvements.

5. Moral Fictionalism

Moral fictionalism is a more recent anti-realist view that emerges primarily as a response to moral error theory.13 It begins by accepting the error theorist’s conclusion: that moral claims, when taken literally as descriptions of objective moral facts, are systematically false because such objective moral properties do not exist. However, unlike abolitionism (which might advocate abandoning moral discourse altogether), fictionalism suggests that we can or should continue to use moral language and engage in moral thought and discourse as a kind of “useful fiction”.38 Proponents argue that we can “make believe” or pretend that moral claims are true because doing so has significant practical benefits, such as promoting social cooperation, regulating behavior, and bolstering self-control against temptation.46

• Richard Joyce: A key contemporary proponent of moral fictionalism, particularly in works like The Myth of Morality (2001) and The Evolution of Morality (2006).13 Joyce, an error theorist, argues that moral thinking is indeed based on a false presupposition of objective, categorical reasons for action (reasons that apply irrespective of an agent’s desires or goals).35 However, he contends that this way of thinking has instrumental value; it evolved because it helped our ancestors cooperate and thrive.35 Therefore, even after recognizing the “error” in morality, we might have good pragmatic reasons to retain moral discourse as a fiction, to continue to “speak with the vulgar but think with the learned”.46 Moral fictionalists might suggest we adopt an attitude of “acceptance” rather than “belief” towards moral propositions in everyday contexts, while acknowledging their falsity in more critical, philosophical moments.60

• Arguments for Moral Fictionalism:

• Retains Practical Benefits: It allows us to retain the practical and social benefits of morality (e.g., facilitating cooperation, guiding action, strengthening resolve) without committing to what the fictionalist sees as untenable ontological claims about objective moral facts.46

• Avoids Radical Abolitionism: It offers an alternative to the potentially disruptive or undesirable consequences of completely abandoning moral thought and language.

• Addresses the “Now What?” Problem: It provides a constructive answer to the question of what to do after accepting moral error theory.

• Criticisms of Moral Fictionalism:

• Psychological Plausibility: A major concern is whether it is psychologically plausible or stable for individuals to consciously treat morality as a fiction while still being genuinely motivated by it or taking it seriously in their practical lives.60 Can one truly “make believe” in morality with the same commitment and effect as genuine belief?

• Sincerity and Authenticity: Could widespread adoption of moral fictionalism lead to cynicism, insincerity, or a general weakening of moral commitment in society? If moral claims are known to be fictions, how can they sustain genuine moral disagreement, condemnation of wrongdoing, or praise for virtue?.60

• Phenomenology of Moral Commitment: Critics argue that fictionalism fails to capture the deep, often unshakeable, phenomenology of moral conviction. Many people experience moral demands not as useful pretenses but as genuinely binding and objectively authoritative.

• Motivational Efficacy: If the motivational power of moral judgments stems, in part, from the belief in their objective truth or authority, then revealing morality as a fiction might undermine this very motivational efficacy that fictionalists wish to preserve.60

The psychological challenge is perhaps the most pressing for moral fictionalism. Can individuals successfully compartmentalize their critical disbelief in objective morality from their practical engagement with moral norms as if they were true? If the “special motivational power” of moral beliefs, which Joyce highlights as a reason to retain them fictitiously 47, depends on an implicit or explicit belief in their truth or objective authority, then the very act of recognizing them as fictions might erode this power. This raises questions about the long-term viability and psychological stability of adopting a fictionalist stance towards something as central to human life as morality.

D. Arguments Supporting Moral Anti-Realism (General)

Across its various forms, moral anti-realism draws support from several general lines of argument that challenge the plausibility of objective, mind-independent moral facts.

• Moral Diversity/Disagreement: As noted, the vast and persistent diversity of moral beliefs and practices across cultures and historical periods is a cornerstone argument for many anti-realists.7 Anti-realists argue that this diversity is better explained by seeing morality as a human construction, an expression of varying attitudes, or a reflection of different social needs and conventions, rather than as imperfect attempts to grasp a single set of objective moral truths. If objective moral facts existed, one might expect more convergence over time, but deep disagreements often persist.
• Metaphysical Parsimony (Ockham’s Razor): Anti-realist theories often claim to be more metaphysically parsimonious than moral realism.49 They avoid positing a realm of objective moral facts or properties, which are frequently characterized by critics (and some proponents) as ontologically extravagant, “queer,” or difficult to integrate into a naturalistic worldview. By not multiplying entities beyond necessity, anti-realism can present itself as a more streamlined and less metaphysically burdensome account of morality.
• Epistemological Simplicity: Anti-realism sidesteps the difficult epistemological challenge of explaining how human beings could gain reliable cognitive access to mind-independent moral truths, especially if these truths are non-natural.9 If morality is not about knowing objective facts, then the problem of how we could know such facts does not arise in the same way.
• Explanatory Power for Moral Variation: Anti-realism is argued to possess greater explanatory power when it comes to accounting for why moral beliefs and practices vary so widely across different societies and historical epochs.7 If moral systems are human creations or expressions of culturally conditioned attitudes, then such variation is precisely what one would expect. Realists, in contrast, must explain this diversity as widespread error or incomplete understanding of objective truths.
• Compatibility with a Naturalistic Worldview: Many forms of moral anti-realism are perceived as being more easily reconcilable with a scientific, naturalistic understanding of the world.12 Since they typically do not require the existence of non-natural moral properties or special epistemic faculties to detect them, they align more comfortably with an ontology that prioritizes entities and processes studied by the natural and social sciences.

One of the strongest intuitive attractions of anti-realism lies in its straightforward explanation of moral diversity.7 If morality is understood as a human construct, a product of cultural evolution, or an expression of individual or collective attitudes, then the observed variation in moral codes across different cultures and historical periods is not only unsurprising but entirely expected. Moral realists, in contrast, face the more complex task of explaining why, if objective moral truths exist, there is such widespread and persistent disagreement about them. They must appeal to factors like cognitive limitations, cultural biases, insufficient information, or the inherent difficulty of discerning subtle moral truths. This makes the argument from moral disagreement a central battleground in the metaethical debate, with both realists and anti-realists claiming that this phenomenon, when properly interpreted, lends support to their respective views, albeit through fundamentally different explanatory lenses.

E. Key Challenges and Criticisms (General)

Despite the arguments in its favor, moral anti-realism faces a number of profound and persistent challenges, primarily concerning its ability to account for core features of our moral experience and discourse.

• Problem of Moral Objectivity and Normativity: A central and overarching challenge for all forms of anti-realism is to adequately explain the apparent objectivity and binding normative force that morality seems to possess. If moral judgments are merely expressions of subjective feeling, reflections of cultural convention, systematically false claims, or useful fictions, then why should we take moral demands seriously, especially when they conflict with our self-interest or desires? How can anti-realist theories make sense of concepts like moral obligation, moral rights, or the sense that some actions are categorically wrong, regardless of personal or societal approval? This is often referred to as the problem of accounting for moral authority.
• Inability to Ground Moral Condemnation of Heinous Acts: Anti-realism, particularly in its more subjectivist or relativist forms, struggles to provide a robust and universally acceptable basis for condemning actions that are widely considered heinous, such as genocide, torture, or slavery. If the wrongness of such actions is only “wrong” relative to a particular individual’s feelings, a specific cultural viewpoint, or if statements condemning them are merely expressions of disapproval without objective truth, it seems to weaken the force and universality of our condemnation. This can lead to the uncomfortable implication that there is no objective basis for saying that, for example, the Holocaust was truly and unequivocally evil.
• Loss of Meaningful Moral Progress: If there are no objective moral standards by which to measure change, the concept of moral progress becomes difficult, if not impossible, to sustain.31 Societies may change their moral codes over time (e.g., abolishing slavery, granting equal rights to women), but if anti-realism is true, it is hard to argue that these changes represent genuine moral improvement rather than just shifts in prevailing attitudes or conventions. Progress implies movement towards a better, more correct state, which seems to require an objective benchmark.
• Trivialization of Moral Discourse and Disagreement: Some critics argue that certain anti-realist theories, especially simpler forms of emotivism or subjectivism, risk trivializing moral debate and disagreement.45 If moral arguments are ultimately just clashes of feeling, expressions of non-negotiable attitudes, or assertions of conflicting cultural norms without any prospect of rational resolution based on objective truth, then much of what we take to be serious moral deliberation appears to be misguided or futile.
• The “Now What?” Problem for Error Theory and Fictionalism: As previously mentioned, theories like moral error theory (which claims all positive moral judgments are false) and moral fictionalism (which suggests we treat morality as a useful pretense) face a significant practical challenge: what are the implications for how we should live and organize our societies if morality, as traditionally understood, is fundamentally flawed or a fiction?.46 Should we attempt to abandon moral talk altogether (a position known as abolitionism), or can we coherently and effectively continue to use it in some modified, non-committal way? These questions raise deep concerns about the practical viability and psychological stability of such views.

Perhaps the most persistent and difficult general challenge for the diverse family of anti-realist theories is to adequately explain the normative authority of morality. If moral claims do not reflect objective facts about what we ought to do, or what is genuinely valuable, then why should these claims guide our actions, especially when doing so is costly, difficult, or runs contrary to our deeply felt desires or perceived self-interest? Different anti-realist theories attempt to reconstruct normativity in various ways—for example, by appealing to the pragmatic benefits of shared conventions (as in some forms of relativism or contractualism), the internal consistency of our commitments (as in some expressivist views), or the instrumental value of moral thinking for achieving our goals (as in fictionalism). However, critics often find these reconstructions insufficient to capture the robust, seemingly categorical, and binding force that we typically associate with genuine moral obligations. The success of any anti-realist theory often hinges on its ability to provide a plausible and compelling account of moral normativity without recourse to the objective moral facts posited by realists.

IV. Comparative Analysis and Key Areas of Contention

The debate between moral realism and anti-realism unfolds across several key philosophical domains, each presenting distinct areas of contention. Understanding these specific battlegrounds is crucial for appreciating the nuances of the overarching dispute.

A. The Nature of Moral Language: Semantic Debates

A primary point of divergence concerns the meaning and function of moral language.

• Cognitivism vs. Non-Cognitivism: Moral realists, along with some anti-realists like error theorists, subjectivists, and relativists, are cognitivists. They believe that moral statements (e.g., “Honesty is good,” “Stealing is wrong”) express beliefs and are therefore truth-apt, meaning they are capable of being true or false.7 The truth or falsity depends on whether they accurately represent the relevant moral facts (for realists) or correspond to individual/cultural attitudes (for subjectivists/relativists), or, in the case of error theory, are all false because the presupposed moral facts do not exist.
  Non-cognitivists (including emotivists, prescriptivists, and other expressivists), on the other hand, deny that moral statements primarily express beliefs or describe facts.7 Instead, they argue that the primary function of moral language is non-descriptive: to express emotions (Ayer, Stevenson), issue commands (Hare), or voice attitudes or commitments to norms (Blackburn, Gibbard).7 For non-cognitivists, moral utterances are not truth-apt.
• The Frege-Geach Problem: This remains a critical test, particularly for non-cognitivist semantics.16 As previously discussed, the problem highlights the difficulty for non-cognitivists in explaining how moral terms retain consistent meaning and logical function when embedded in complex, unasserted contexts (e.g., conditionals, negations). If “wrong” in “Stealing is wrong” means “Boo to stealing!”, its meaning seems to change in “If stealing is wrong, then…”. This challenges the non-cognitivist’s ability to account for the validity of moral arguments. Sophisticated expressivists like Blackburn and Gibbard have offered complex responses, often involving analyses of higher-order attitudes or commitments to norms governing such linguistic constructions.

B. The Existence and Nature of Moral Properties: Ontological Debates

The ontological status of moral properties is perhaps the most fundamental point of disagreement.

• Mind-Independent Objective Properties vs. Mind-Dependent or Non-Existent Properties: Moral realists assert that moral properties (e.g., goodness, rightness, justice) exist objectively and are mind-independent features of actions, persons, or states of affairs.7 Moral anti-realists, in contrast, either deny the existence of such properties altogether (as in non-cognitivism and error theory) or argue that if moral properties exist, their existence is mind-dependent, contingent on human attitudes, beliefs, or social constructs (as in subjectivism and relativism).7
• Natural vs. Non-Natural Properties (within Realism): If moral properties are objective, a further debate within realism concerns their metaphysical nature. Moral naturalists identify moral properties with (or reduce them to) natural properties (e.g., those discoverable by science, such as properties related to well-being or social stability).7 Moral non-naturalists argue that moral properties are sui generis, irreducible to natural properties, and possess a unique normative character.7
• Mackie’s “Queerness” Argument: This argument directly targets the ontology of realist moral properties.13 Mackie contended that objective values, if they existed with the kind of intrinsic prescriptivity that moral discourse seems to attribute to them, would be metaphysically unlike any other known entities in the universe. This “queerness” provides a strong motivation for anti-realist positions like error theory.

C. Moral Knowledge and Justification: Epistemological Debates

How we come to know moral truths (if they exist) and how moral beliefs are justified is another major area of contention.

• Possibility of Objective Moral Knowledge vs. Skepticism/Alternative Justifications: Moral realists are committed to the possibility of objective moral knowledge.7 They believe we can have justified true beliefs about moral matters. Anti-realists vary: non-cognitivists typically reframe the issue away from knowledge of facts towards the appropriateness of attitudes or commitments; error theorists are moral skeptics in the sense that they believe all our positive moral beliefs are false, hence unknowable as truths; subjectivists and relativists may allow for a kind of relative knowledge or justification, but not objective, universal moral knowledge.
• Realist Epistemologies: Realists propose various accounts of moral epistemology, including intuitionism (basic moral truths are self-evident and known directly through rational intuition, favored by non-naturalists like Moore, Ross, and Price) 8, coherentism (moral beliefs are justified by their coherence with a broader system of beliefs, often favored by naturalists like Brink) 8, and other forms of foundationalism.
• The Epistemological Challenge to Realism: A key challenge for realism, especially non-naturalist realism, is to explain how we could have epistemic access to these objective moral truths if they are non-natural or “queer”.9 If moral properties are not detectable by ordinary empirical senses, what faculty allows us to know them?
• The Justification Challenge for Anti-Realism: Conversely, some forms of anti-realism face the challenge of explaining how there can be any meaningful moral justification or rational moral debate if there are no moral truths to be discovered or if moral judgments are merely expressions of non-cognitive states.
• Evolutionary Debunking Arguments (EDAs): EDAs directly target moral epistemology by arguing that the evolutionary origins of our moral beliefs undermine their epistemic justification, particularly if moral realism is true.13 If our moral faculties evolved for fitness rather than truth-tracking, our moral beliefs may be unreliable guides to objective moral reality. Realist responses often focus on the role of reason in correcting evolved biases or on potential convergences between fitness-enhancing beliefs and moral truths.

D. Moral Motivation: Psychological Debates

The relationship between making a moral judgment and being motivated to act accordingly is a complex psychological and philosophical issue.

• Internalism vs. Externalism: Motivational internalism holds that there is a necessary, internal connection between sincerely judging something to be morally right (or wrong) and being motivated (at least to some degree) to act (or refrain from acting) accordingly.8 Motivational externalism denies this necessary connection, arguing that moral judgment and motivation are distinct, and any link between them is contingent (e.g., dependent on having a pre-existing desire to be moral).8
• Implications for Realism and Anti-Realism: Non-cognitivists often favor internalism, arguing that the inherent motivational force of moral judgments supports their view that these judgments are expressions of motivating attitudes (like desires or emotions) rather than inert beliefs.8 Realists are divided: some accept internalism and argue that moral beliefs themselves can be intrinsically motivating or are necessarily connected to reasons for action 8; others adopt externalism, explaining cases of amoralists or those who act against their moral judgments through factors like weakness of will, while maintaining that the moral judgment itself remains a cognitive belief about objective facts.8

E. Explaining Moral Disagreement and Diversity

Both realists and anti-realists must offer compelling explanations for the pervasive phenomenon of moral disagreement and cultural diversity in moral codes.

• Realist Explanations: Realists typically explain moral disagreement by appealing to factors such as: errors in non-moral factual beliefs that influence moral judgments; irrationality or bias in moral reasoning; the complexity or subtlety of some moral truths making them difficult to discern; or incomplete information. They may also argue that some apparent disagreements mask deeper underlying agreements on fundamental principles.31
• Anti-Realist Explanations: Anti-realists generally find moral diversity easier to explain. If morality is a human construct, an expression of varying attitudes, or relative to cultural frameworks, then diversity is precisely what one would expect.7 For example, cultural relativists see differing moral codes as simply different, equally valid ways of life adopted by different societies.31 Emotivists see disagreements as clashes of emotional responses.

The positions taken on the nature of moral language (semantics), the existence and character

Handwritten Notebook Pages

Source

Open Moral realism notebook pages — start at notebook p. 30 (file not included in this release).

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