Author: Ian Tully
Category: Ethics
Wordcount: 998
Though we often disagree about which actions are morally wrong, most people agree that some actions really are wrong. One obvious example is abusing children for fun.
According to the meta-ethical theory known as “moral error theory,” it is false that abusing children for fun is morally wrong (and false that it’s morally right, too!).[1] This is because, according to error theory, all moral judgments are false.[2]
This essay explores this counterintuitive view.
1. Understanding the Error Theory
The error theory originates with Australian philosopher J.L. Mackie (1917–1981).[3] It is committed to two central theses:
- the Conceptual Thesis: moral statements aim to describe moral facts about the world. When we use moral language, we’re not merely expressing attitudes or emotions—we’re trying to state truths about moral reality;
- the Substantive Thesis: there are no moral facts or properties that make moral claims true. Therefore, all claims that something is wrong, bad, unjust, etc. are false; they refer to properties that simply don’t exist.
A helpful analogy is with talk of witches. When people in Salem accused others of being witches, they were describing individuals as having magical powers. But there are no such magical powers, so those accusations were false.
Error theorists think moral language is similar: a claim“this action is wrong” is false because there are no facts about what’s wrong: there is no property or characteristic “wrong” that could make such claims true. Moral properties aren’t real, so any claims that appeal to them are in error.
2. Moral Realism
To better understand error theory, we should understand its main alternative, “moral realism.”
Moral realists believe that ethics is real: there are moral properties or facts that make actions wrong and not wrong. Furthermore, these properties or facts aren’t “created” by any individual or cultures: concerning our initial example, realists think that abusing children for fun is wrong and that it would be wrong even if somehow everyone thought it was right.[4]
3. The Arguments
Why accept the moral error theory? Mackie offers two main arguments: the Argument from Queerness and the Argument from Disagreement.
3.1. Queerness
Mackie claims that if there were moral facts or properties, they would be metaphysically and epistemologically “queer”—that is, unlike anything else in the universe. He claims: “If there were objective values, then they would be entities…of a very strange sort, utterly different from anything else in the universe.”[5]
What makes them strange is their supposed intrinsic normative authority: “[S]omething’s being good both tells the person who knows this to pursue it and makes him pursue it… just because the end has to-be-pursuedness somehow built into it.”[6]
In other words, objective moral values would have an inescapable “oughtness” built into them. They would give reasons for action to all rational agents, regardless of anyone’s desires or interests. But this seems mysterious or even unintelligible. Mackie suspects this idea of categorical moral authority is a leftover from religious thinking—like trying to have divine laws without a divine lawgiver.[7]
So, Mackie argues that because such properties are metaphysically suspect, we should reject them—and thus reject believing that moral claims are ever true.
3.2. Disagreements
Mackie’s second argument appeals to the widespread and persistent disagreement about moral issues. Unlike scientific disagreements, which tend to diminish over time as evidence accumulates, moral disagreements often seem intractable.
According to Mackie, this suggests that moral claims are not tracking any objective reality. If there were moral facts “out there” to be discovered, then—over time—we should expect increasing agreement about them, as with empirical facts. Mackie claims that we don’t see such increasing agreement and thinks this suggests that people are not perceiving any moral truths, because there are none.[8]
4. Responses
Moral error theory is a bold and unsettling view that is highly contrary to common sense—that some actions are profoundly wrong, and that that’s the truth—and most philosophers reject it. Let’s look at some responses to both arguments.
4.1. Reply to Queerness
Moral realists are reluctant to give up the idea that moral claims aim to describe objective moral facts. So they accept the Conceptual thesis but reject the Substantive Thesis, arguing that categorical moral reasons aren’t so mysterious or “queer” after all.[9]
One common response is to draw a parallel with “epistemic reasons”—reasons for belief. For instance, the fact that the Earth orbits the Sun—or observations about such matters—are reasons to believe heliocentrism, regardless of anyone’s desires.
In general, it seems that there are things that should and should be believed, from an intellectual or epistemic point of view—e.g., we should believe what the best evidence supports—regardless of how we feel about that. If categorical epistemic reasons exist, then categorical moral reasons might too. Thus, the alleged “queerness” of moral reasons may not be so queer after all.
4.2. Reply to Disagreements
Mackie’s appeal to disagreement also faces challenges.
First, disagreement is not unique to ethics. People also disagree about empirical and scientific matters, particularly when evidence is complex, incomplete, or hard to interpret. Disagreement, by itself, does not show that there are no facts to be discovered.
Second, moral disagreements sometimes result from non-moral differences, such as factual misunderstandings, poor reasoning, different background assumptions, and conflicts of interest. When people start from very different perspectives, they may arrive at very different moral conclusions, even if there are moral facts.
Third, disagreement is compatible with objective facts. Even in mathematics or physics, experts sometimes disagree, yet there seem to be facts of the matter. Persistent disagreement might reflect human limitations, not the nonexistence of truth.
Thus, the existence of moral disagreement doesn’t necessarily support error theory.
5. Conclusion
Mackie’s error theory offers a provocative challenge to both common sense and moral realism. We might wonder if error theory or moral realism is more reasonable for people to believe. If either view is supported by better arguments, and we should believe what’s supported by better arguments, that ultimately might undermine the case for the error theory.
Notes
[1] “Meta-ethics” is the part of philosophical ethics that investigates whether moral judgements are true or false and, if so, what makes moral judgments, or beliefs, true and false. In general, beliefs are made true and false by facts, so are there moral facts? Meta-ethics also typically concerns whether and how moral judgments can be reasonably believed or known.
What’s often called “normative ethics” investigates different theories of what might make actions wrong and not wrong.
[2] Some may be wondering how error theorists can claim that all moral statements are false: after all, by the law of excluded middle, a statement and its negation can’t both be false. There are a number of ways to address this concern: see Sinnott-Armstrong (2006) and Olson (2010) for details.
[3] Other philosophers have developed this type of theory in new ways. See Joyce (2001), Olson (2010) and Garner (2012), among others.
[4] For an introduction to moral realism, and many of the other issues of this essay, see Ethical Realism, or Moral Realism by Thomas Metcalf. Realists deny that cultural attitudes determine what’s wrong and not wrong (or that moral properties are identical to or depend on facts about cultural approval, etc.), and they usually deny that God’s commands would make actions wrong either (or that moral properties are identical to or depend on facts about what God might command, etc.). See Cultural Relativism: Do Cultural Norms Make Actions Right and Wrong? by Nathan Nobis and Because God Says So: On Divine Command Theory by Spencer Case.
[5] See Mackie (1977, p. 77).
[6] See Mackie (1977, p. 78).
[7] For similar claims about ethics presupposing a being that gives commands or laws, see G. E. M. Anscombe’s “Modern Moral Philosophy” by Daniel Weltman.
[8] For a discussion of the steady of increase of ethical agreement over the centuries about, e.g., the wrongness of slavery, the wrongness of torture and cruel and unusual punishment, the wrongness of denying women the right to vote, and more—and thus evidence for progress in widespread moral thinking and action—see Huemer’s (2013) TEDx talk “The Progress of Liberalism.”
[9] See, e.g., Shafer-Landau (2005: 111); Kelly et al (2007); Cuneo (2012). Also see Cuneo (2007) and Rowland (2013).
References
Cuneo, Terence. (2012). “Moral Naturalism and Categorical Reasons.” In Susana Nuccetelli and Gary Seay, eds. Ethical Naturalism: Current Debates. New York: Cambridge University Press.
Cuneo, Terence. (2007). The Normative Web. New York: Oxford University Press.
Garner, Richard. (2006). “On The Genuine Queerness of Moral Properties and Facts.” In Arguing About Metaethics, Andrew Fischer and Simon Kirchin, eds. New York: Routledge.
Huemer, Michael. (2013). “The Progress of Liberalism.” TEDx Talks. YouTube.
Joyce, Richard. (2001). The Myth of Morality. New York: Cambridge University Press.
Mackie, John L. (1977) Ethics: Inventing Right and Wrong. New York: Penguin Books.
Olson, Jonas. (2010) “In Defense of Moral Error Theory,” in Michael Brady, ed., New Waves in Metaethics, Basingstoke: Palgrave Macmillan, 62-84.
Rowland, Richard. (2013) “Moral Error Theory and The Argument From Epistemic Reasons.” Journal of Ethics and Social Philosophy Vol 7 No 1.
Shafer-Landau, Russ. (2005) “Error Theory and the Possibility of Normative Theory.” Philosophical Issues (Normativity) 15, 107-120.
Sinnott-Armstrong, Walter. (2006) Moral Skepticisms. Oxford: Oxford University Press.
For Further Reading
Kevin M. DeLapp. “Metaethics.” Internet Encyclopedia of Philosophy.
Shin Kim. “Moral Realism.” Internet Encyclopedia of Philosophy.
Tramel, Peter. Moral Epistemology. Internet Encyclopedia of Philosophy.
Related Essays
Ethical Realism, or Moral Realism by Thomas Metcalf
G. E. M. Anscombe’s “Modern Moral Philosophy” by Daniel Weltman
Because God Says So: On Divine Command Theory by Spencer Case
Cultural Relativism: Do Cultural Norms Make Actions Right and Wrong? by Nathan Nobis
“That’s Subjective”: Subjectivism about Truth, Beauty, and Goodness by Nathan Nobis
Evolution and Ethics by Michael Klenk
Reason is the Slave to the Passions: Hume on Reason vs. Desire by Daniel Weltman
Revision History
This essay was revised and updated by the Editors of 1000-Word Philosophy and reposted on July 23, 2025. The original essay, posted on April 14, 2014, is here.
About the Author
Ian Tully is an Assistant Professor in the School of Nursing and Center for Global Health Ethics at Duquesne University. Prior to that he was a Postdoctoral Fellow in Philosophy and Mental Disorder at Johns Hopkins University’s Berman Institute of Bioethics. He completed his PhD in philosophy at Washington University in St. Louis. He is interested in ethics, metaethics, moral psychology, and the philosophy of mind. ianmtully.wixsite.com/iantullyphilosophy
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