Hi world! I wrote this quasi-survey on metaethics for my mandatory undergraduate writing class. As a result, many concepts are overly simplified, and the essay lacks strong logical rigor, since it’s intended for readers without a solid background in philosophy. Unfortunately, the essay doesn’t delve deeply into intuitionism or non-cognitivism, as my professor didn’t want to read a 20+ page paper—and I also had to study for my finals. In any case, I’d appreciate any information or elaboration on these two stances. General feedback is also very welcome!



The Road to Error Theory

In this essay, we will embark on a journey in search of the nature of ethics. To be precise, our focus will not be on normative ethics, which addresses questions such as “What is good?”, “What ought one to do?”, or “Which actions are praiseworthy?” Rather, we will turn our attention to metaethics, which adopts a broader philosophical perspective and seeks to uncover the fundamental nature and meaning of morality itself. The aspects of ethics we are concerned with here include its metaphysical status, epistemological validity, as well as its psychological and semantic dimensions.
More specifically, I aim to establish the position of Error Theory as the least refutable view in metaethics. I use the phrase “least refutable” to indicate: 1) the insufficiency of my own knowledge and 2) the ambiguous nature of ethics as a field itself.
Error theory is identified as a form of moral-antirealism, which refutes that moral statements report objective truths. However, to formally define this position, it is necessary to clarify some key terminologies.

Terminologies and Definitions:

First, metaethics can be broadly divided into two camps: moral realism and moral anti-realism. Moral realists maintain that moral statements are objectively true or false—that is, at least some moral claims report objective moral facts. Moral anti-realists, on the other hand, reject this thesis.
Second, we must distinguish moral absolutism from moral relativism. Moral absolutism is the view that a single, universal set of moral principles applies to all individuals and cultures, without exception. Moral relativism, by contrast, holds that different moral principles apply to different individuals or groups, depending on cultural, historical, or situational contexts. It is important to note that moral realism is not equivalent to moral absolutism, nor is moral anti-realism equivalent to moral relativism. For instance, one could be a moral realist and a relativist by holding that different objective moral truths apply to different cultural or social contexts. In such a case, a person would be both a relativist and a realist.
Thirdly, we should consider the distinction between moral cognitivism and non-cognitivism. Moral cognitivism holds that moral beliefs are truth-apt propositions—that is, it is possible for them to obtain a truth or false value, just like all other beliefs. On the other hand, non-cognitivism hold that moral beliefs fundamentally reflect mental states such as emotions, desires or instincts, which are not truth-apt (e.g. it does not make sense to say being angry is true or false).
The table below should help conceptualizing these distinctions:
Moral Realism Moral claims report objective facts
Moral Anti-realism Moral claims do not report objective facts
Moral Absolutism The same set of moral statements must be applied to all groups of individuals.
Moral Relativism Different moral statements are applied to different groups of individuals.
Moral Cognitivism Moral statements are truth-apt (can be true or false).
Moral Non-Cognitivism Moral statements are not truth-apt.

Now we are in a good position to formally define error theory. Error theory is a form of cognitivist moral anti-realism. That is, it holds that moral beliefs are truth-apt and therefore does not oppose the view that it is at least possible for moral beliefs to be true. However, moral statements are not actually true in the world we live in. An analogous illustration of this position is the case of unicorns: we assert that it is possible for them to exist, since no logical contradiction follows from that, but we also believe that they do not actually exist. Similarly, error theorists merely assert that moral statements fail to report any objective fact—not that they cannot possibly do so.
While it was mentioned earlier that moral relativism does not necessarily entail moral anti-realism, it is generally the case that the latter—including error theorists—use the former as part of their argument. So depending on whether an error theorist adopts relativistic arguments, error theory could be interpreted as either a form of moral relativism or moral absolutism.


Methodology:


Moral realism often appears to be the more intuitive position. The very existence of ethics as a field of meaningful philosophical inquiry—rather than being unanimously reduced to mere non-objective instinct—suggests that people find moral questions worthy of analysis and reflection. Moreover, the structures of our society are largely grounded implicitly in moral principles; legislations and political ideologies, for instance, often appeal to some form of moral authority. This reliance implies that people are naturally committed to moral realism, for laws would lose much of their normative power if morality were seen as entirely non-objective. As David Brink puts it: “We begin as (tacit) cognitivists and realists about ethics.… Moral Realism should be our metaethical starting point, and we should give it up only if it does involve unacceptable metaphysical and epistemological commitments” (1989: 23–24). Hence, in this essay, we shall likewise begin with the assumption of moral realism, and proceed to explore the explanatory limitations it faces. More specifically, by considering these limitations of moral realism, we shall see that the “road to error theory” is actually not as obscure as one would expect it to be. It would turn out that error theory is the direct conclusion of these limitations.
This, then, indicates that the arguments for error theory mainly take the form of reductio ad absurdum—that is, they assume the truth of the opposing view in order to reveal the absurd consequences that would follow from that assumption. One might criticize error theory on the grounds that it consists primarily, if not entirely, of destructive arguments. However, the absence of constructive arguments does not undermine the validity of the position under consideration. Firstly, the burden of proof in this contention lies primarily—at least prima facies—on the shoulder of the realists, for they are the party that seek to establish the existence of certain facts—namely moral facts. Consider the following analogy: which party has the burden of proof: Party A, who supports the existence of unicorns, or Party B, who denies this claim?
This brings us to the second reason as to why error theory remains valid despite being built on destructive arguments: the fact that moral realism and anti-realism are mutually exclusive. An assertion about an objective fact is either true or false—that is, a fact either exist or do not exist, and there exists no middle ground. In this light, anti-realism can be understood as the negation of realism. Thus, the point is more clearly demonstrated by the logical representation: either x or not x—in which case, the successful refutation of one necessarily entails the acceptance of the other.
Here is a list of refutations to moral realism (=arguments for error theory) that will be presented: 1) Moore’s Open Question Argument, 2) Hume’s Is-Ought Problem, and 3) Markie’s Argument from Queerness.

Moore’s Open Question Argument—The Failure of Trying to Define Moral Statements:


The father of Utilitarianism, Jeremy Bentham, begins his foundational work An Introduction to the Principles of Morals and Legislation with the following statement: “Nature has placed mankind under the governance of two sovereign masters, pain and pleasure. It is for them alone to point out what we ought to do… By the principle of utility is meant that principle which approves or disapproves of every action whatsoever according to the tendency it appears to have to augment or diminish the happiness of the party whose interest is in question: or, what is the same thing in other words, to promote or to oppose that happiness. I say of every action whatsoever, and therefore not only of every action of a private individual, but of every measure of government.” (1789: 1) Observe how readily Bentham equates goodness with the pursuit of pleasure and the avoidance of pain, justifying this definition by appealing to nature.
However, this definition of goodness is open to contention. For surely utility cannot be the measure of all things. Consider Judith Jarvis Thomson’s Organ Donor Trolley Problem: “David is a great transplant surgeon. Five of his patients need new parts. One needs a heart, the others need, respectively, liver, stomach, spleen, and spinal cord. But all are of the same, relatively rare, blood-type. By chance, David learns of a healthy specimen with that very blood-type. David can take the healthy specimen's parts, killing him, and install them in his patients, saving them. Or he can refrain from taking the healthy specimen's parts, letting his patients die.” (Killing, Letting Die, and the Trolley Problem: 206)
Killing one innocent person to save five seems intuitively wrong, even if one generally adopts utilitarian stance. However, does that mean utilitarianism is wrong? This is beyond the scope of our journey. But the case of utilitarianism serves as an example of the struggles of moral realism: No matter how we define goodness, there always exist some open questions that cannot be explained by the very definition of goodness (In general, this is true for all moral terms; goodness here serves as a prime example, and will continue be the representative example in this section). We shall see that this observation presents a huge challenge not only for utilitarianism, but all positions that aim to define goodness in terms of things other than goodness itself.
G. E. Moore fundamentally rejects moral naturalism, the view that moral statements can be explored or confirmed scientifically and empirically. In his view, naturalists commit what he famously calls the “naturalistic fallacy”—the mistake of trying to define the simple, unanalyzable property of goodness in terms of some natural property, such as pleasure, desire-satisfaction, or evolutionary fitness. Unknown to Moore himself, his argument in fact challenges not only moral naturalism, but all metaethical positions that aim to define moral terms in a non-analytical way (definition in terms of ideas other than the term being defined).
To clarify this point, Moore draws a distinction between simple and complex ideas, arguing that goodness falls into the category of the former. A simple idea is one that cannot be further reduced into constituent parts; it is an atomic element of our conceptual framework. In contrast, a complex idea is composed of multiple simple ideas and can be analyzed or broken down into them.
Therefore, by asserting that goodness is a simple, irreducible quality, Moore rejects any complex definition of morality, including Utilitarianism.
Moore’s argument takes the following form:

Let goodness be equivalent to some complex idea X (e.g. the pursuit of the desire as desired by all humans)

Then goodness = X, just as saying a triangle is a plane figure with three straight sides and three angles

This means that asking whether goodness is really X should yield no meaningful and substantial answer, just as asking whether a triangle is a plane figure with three straight sides and three angles

However, it seems that asking whether goodness is really X do yield meaningful and substantial answer (consider the case of Utilitarianism and Organ Donor Trolley Problem)

Therefore, goodness cannot be equivalent to some complex idea X

In this way, Moore refutes any attempt to define goodness in terms of anything other than itself. He concludes: “Good is a simple notion, just as yellow is a simple notion… We know what ‘yellow’ means, and can recognize it wherever it is seen, but we cannot actually define it. Similarly, we know what ‘good’ means, but we cannot define it” (Principia Ethica, §10). Therefore, any moral realist position that aims to define moral concepts in a synthetic or a posterior way render themselves susceptible to Moore’s Open Question Argument.



Hume’s Is-ought Problem:

Hume’s is-ought problem presents an epistemological challenge to moral naturalism. According to David Hume, no statement expressing what one ought to do can be logically derived from statements describing what is the case, unless an ought-statement is already assumed. In other words, the fact that X is Y does not entail that X ought to be Y. There exists an inferential gap between descriptive and normative claims, which cannot be bridged without introducing a normative premise previously already. For example, even if we observe—through scientific methods—that humans tend to pursue happiness and avoid pain, it does not follow that humans ought to act this way. Thus, no set of purely nonmoral premises can, by itself, entail a moral conclusion. As a result, even if the moral realists manage to overcome Moore’s Open Question Argument, they still face the epistemological challenge posed by the is-ought gap. That is, even if we successfully define what moral terms mean, we still need to explain how we can justify the logical leap of moral knowledge.
The only viable way for moral realists to address both Moore’s and Hume’s challenges is to assume that moral facts are known a priori—that is, propositions that can be known independently of experience, through reason alone (or, as Descartes puts it, through the “natural light of reason”). Moral intuitionists, a subset of realists who adopt this view, aim to construct a coherent moral system grounded in fundamental moral axioms that are taken to be self-evident, placing particular emphasis on formalism. However, identifying such moral axioms is an arduous—if not impossible—task, given the inherent diversity and ambiguity of moral discourse. The following argument in favor of error theory will focus on these two features of morality.


Mackie’s Argument from Queerness:


J. L. Mackie first introduced the term “error theory” in his 1977 book Ethics: Inventing Right and Wrong. He writes: “If there were objective values, then they would be entities or qualities or relations of a very strange sort, utterly different from anything else in the universe. Correspondingly, if we were aware of them, it would have to be by some special faculty of moral perception or intuition, utterly different from our ordinary ways of knowing everything else” (p. 38, 1977). This is the famous Argument from Queerness, which poses two central challenges to moral realism: one metaphysical, concerning the nature of moral entities, and one epistemological, concerning how we could possibly know them.
The metaphysical challenge highlights a particularly peculiar feature of moral facts: they appear to involve an intrinsically necessary connection between a situation and a corresponding action. Moral statements do not merely describe the world; they seem to command us to act in specific ways under particular conditions. Yet such a prescriptive relationship is absent from other types of beliefs. As Mackie puts it, moral facts possess “qualities or relations of a very strange sort, utterly different from anything else in the universe” (Mackie 1977: 38). Therefore, if one accepts that moral statements report objective truths, one is also committing to the existence of a kind of “objective ethical prescriptivity”. But this is, by its very nature, metaphysically queer. For naturally, it raises the question: what is the ontological origin of such “prescription”? Is it God, a Platonic Form, or some intrinsic metaphysical link between situations and actions themselves? And if such entities or relations do exist, in what form do they exist?
Closely tied to this metaphysical queerness is the epistemological question: if such objective ethical prescriptivity exists, how do we come to know it? As discussed earlier, attempts to define moral statements empirically—by appealing to scientific or naturalistic terms—render themselves susceptible to both Moore’s Open Question Argument and Hume’s Is-Ought Problem. On the other hand, treating moral knowledge as a priori truths would assume “some special faculty of moral perception or intuition, utterly different from our ordinary ways of knowing everything else” (Mackie 1977: 38). This too appears epistemologically suspect.
Additionally, while moral relativism, as aforementioned, is not tantamount to moral anti-realism, it does serve as a strong argument for the latter. In a cross-cultural study, Richard Shweder found that moral concerns differ significantly across cultures. For example, in one Indian town, moral thinking was shaped by ideas of karma, suffering, and personal responsibility, where suffering is often seen as the just consequence of past actions. In contrast, American moral frameworks tend to view suffering as random or meaningless, often divorced from any notion of moral causality (Shweder, 1997). Considering this, if one maintains the existence of objective ethical prescriptivity, then two troubling possibilities emerge:1) Different objective moral values are prescribed to different groups of people; or 2) a single set of universal moral truths exists, but only some groups are epistemically equipped to access them. Either option implies an intrinsic difference between human groups, whether in their ontological status or epistemological capacities. However, within the framework of modern scientific understanding of the human species, such possibilities appear queer.


Conclusion:


Approaching ethics from my own perspective, I find the field deeply problematic. Unlike other branches of philosophy, a systematic and formal treatment of ethics seems impossible. Recall how the brief debate pertaining to utilitarianism was presented. Utilitarians assert a statement, and the opposition brings up a case that would render the utilitarian position counterintuitive. However, the fact that a proposition is counterintuitive does not mean it is illogical. If, in a branch of knowledge, being intuitive is more significant than being logical, then such a branch is substantially flawed, especially if it seeks to describe objective facts. Quantum physics is unimaginably more counterintuitive than Newtonian physics; this does not affect the former’s dominance over the latter. Similarly, in the field of mathematics, Gabriel’s Horn, which states that a shape (formed by rotating y = 1/x, for all x≥1, around the x-axis) could have infinite area yet finite volume, is not rendered invalid due to its counterintuitive nature.
Yet, note how in ethical discussions, the validity of an argument or position is largely grounded in emotions and intuitions. Often, a position is refuted simply because it just does not “feel” right. The presence of such “emotional attachment” thus further obfuscates any attempt to clarify the field. Furthermore, notice also that in discussing ethics, the types of arguments often take the form of examples, analogies, or metaphors. The frequent use of scare quotes in this section (e.g., “feels” right) serves as direct evidence. It is as if we cannot talk about moral truths directly, but only through taking a “detour.”
This observation is not only unique to me—it is the main motivation behind any moral non-cognitivist theory. As mentioned in the beginning, non-cognitivism holds that moral beliefs fundamentally reflect mental states such as emotions, desires, or instincts, and therefore are not to be treated as propositions. In light of the struggles in ethics identified in the previous paragraph, it is not hard to see the advantage and the explanatory power of non-cognitivism. However, the reason error theory—a cognitivist stance—is favored over non-cognitivism in this essay is because, while non-cognitivism effectively addresses some key issues, it introduces new problems of its own. Establishing a robust non-cognitivist stance requires not only destructive arguments, but also constructive ones—something current accounts fail to deliver satisfactorily. Thus, while non-cognitivism may be tempting, one must resist intellectual overreach and recall Socrates’ remark: “ἑν οἰδα ὁτι οὐδεν οἰδα” (One thing I know, that I know nothing).

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