The word ‘meta’ means ‘beyond’ or ‘about’, and as a prefix means a higher level of abstraction of the topic at hand, which is ethics. So metaethics is not concerned with making moral claims – that’s the realm of normative ethics. Metaethics involves making claims about the nature of moral claims.

Let’s take the claim that ‘we ought to keep our promises’. This could be expressed as a moral fact: ‘it is the case that breaking our promises is wrong’. Metaethics asks if moral facts such as these actually exist, or are they merely statements about how we feel about moral issues? If they do exist, what kind of thing are they? Moreover, can we ever know what these facts are? Of course, there is all manner of views about the answers to these questions, and the purpose of this post is to classify them in a way that is comprehensible.

Moral realism

The most important question is whether moral facts exist at all. Moral realists think they do, and so these moral facts make our moral judgments true or false. If I claim that it’s okay to break my promise, and it is a moral fact that ‘it is the case that breaking our promises is wrong’, then my claim is false. Conversely, moral anti-realists reject that there are such things as moral facts (sometime they are called irrealists).

Moral realism is a broad church – there are a wide variety of opinions about what kind of thing moral facts are, and disagreement about the facts themselves. It might even be that moral facts exist, but we have no way to determine what they are – a position known as moral skepticism.

The most important question for moral realists is whether moral facts are objective: whether they exist independently of human beings or not. Moral relativism says moral facts are true or false relative to some human standard. Relativists point to the diversity of moral values across cultures as evidence for their views, and believe that this diversity shows objective moral facts are unlikely. If moral facts aren’t objective, is moral relativism really a form of moral realism? Some philosophers believe it is, while others argue that moral relativism is actually an anti-realist position.

If moral facts are objective, a position sometimes called moral absolutism, what kind of thing are moral facts? Those who hold to naturalism – the belief that only features of our universe exist are natural ones, i.e. those amenable to study by empirical science – must believe moral facts are natural, a position called naturalistic moral realism. There’s a problem with this view though, which faces an objection known as Moore’s Open Question Argument. This argument led Moore to non-naturalistic moral realism, which concludes we must admit the existence of unique non-natural properties such as goodness. There are two options here: either these properties are supernatural, attributable to God or gods in some manner, or they are non-natural and non-supernatural, a position known as non-natural non-theistic moral realism and ably supported by Erik J. Wielenberg. I discuss Wielenberg’s ideas here.

It’s time to mention cognitivism, a term often encountered in metaethics. It’s a theory that says moral claims are expressions of beliefs that can be true or false. This sounds like moral realism, but it’s broader than this (especially if you think moral relativists are not realists). Moral relativists are cognitivists, yes, because they believe moral claims can be true or false. But you can be a cognitivist and believe all moral claims are false. In this case you are what’s called an error theorist – there are no moral facts, it’s all nonsense and you believe all talk of morals is hugely in error. J. L. Mackie is the most famous advocate of this view.

Moral anti-realism

Recall that anti-realists reject that there are things such as moral facts, and so error theorists are also anti-realists as well as being cognitivists! But most anti-realists are noncognitivists: like error theorists, they don’t believe there are such things as moral facts. But unlike error theorists, noncognitivists thinks people who accept moral claims don’t actually have real beliefs about these moral claims, but instead are expressing their attitudes or desires. One form of noncognitivism is called emotivism, where moral claims are said to express our emotions. For this reason it is sometimes known as hurrah/boo theory. and is also a form of expressivism.

I haven’t yet mentioned an important anti-realist position known as moral nihilism, which is that nothing is morally wrong. Nihilism is most often associated with Friedrich Nietzsche, who was not only a moral nihilist but a nihilist about any values at all. This doesn’t sound much different to error theorists, and indeed error theorists are often thought of as moral nihilists.

It should be apparent by now that metaethics is a deep rabbit hole to explore. One useful tool for navigating the topic is the chart shown below, which I believe is the work of David Faraci. You’ll see that there are numerous other metaethical views not mentioned in this overview.  Fortunately, there are many good introductory texts on metaethics, one being Alex Miller’s An Introduction to Contemporary Metaethics which I have seen recommended, as well as Metaethics: An Introduction by Andrew Fisher.