Metaethics is one of the three branches of ethics usually recognized by philosophers, the other being normative ethics and applied ethics. It’s a field of study that tries to understand the metaphysical, epistemological and semantic characteristics as well as the foundations and scope of moral values. It worries about questions and problems such as "Are moral judgments objective or subjective, relative or absolute?", "Do moral facts exist?" or “How do we learn moral values?”.
The metaethical positions are defined by the way authors try to answer the mentioned questions. Garner & Rosen (1967) have proposed a division of such theories based on three major concepts or types of questions: Semantic, Substantial and Justification.
The first group of theories deals with questions pertaining the meaning of moral terms. That is, it tries to solve questions such as "What does right or wrong actually mean?" or "What do people refer to when they say something is right?". It can be further divided into Cognitive and Non-cognitive theories, regarding whether we consider moral values to have a logical structure, expressing truth beliefs, or simply represent emotional responses.
The substantial theories, on the other hand, try to find the answer to the nature of moral judgements. That is, they try to answer questions such as "Are moral values universal, or do they vary from context to context?". This theories can be grouped in three major clusters. Moral universalism postulates that a universal system of ethics is the foundation of all moral judgements and, as such, moral values are absolut. On the opposite side, Moral relativism introduces the idea that these values vary from culture to culture and are sensitive to context - there is no absolute standard. Parallel to both these kinds of theories emerges Moral nihilism, asserting that there are no actions or decisions better than others, right and wrong being non-existent.
Finally, justification theories are worried with how we can justify moral positions or the the need to act morally. It's mainly an epistemological field that tries to solve the problem of deciding whether we can have actual knowledge about moral truths. If we deny such fact, we are faced with Moral skepticism, which asserts no one can have access to knowledge about moral decisions - thus encompassing most non-cognitive theories. On the other hand, if we assume knowledge is possible, we are faced with theories claiming we can gain it through inference - Empiricism or Ethical rationalism - or without it, with an Ethical intuitionism.
Metaethics and Rationality
Luke Muehlhauser has begun a sequence, No-Nonsense Metaethics, where he clais that many of the questions of metaethics can be answered today using modern neuroscience and rationality. He explains how conventional metaethics or "Austere Metaethics" is capable of, after assuming a definition of 'right', choosing the right action given a situation - but useless without assuming some criteria for 'right'. He proposes instead "Empathic Metaethics" which utilizes your underlying cognitive algorithms to understand what you think 'right' means, helps clarify any emotional and cognitive contradictions in it, and then tells you what the right thing to do is, according to your definition of right. This approach is highly relevant for the Friendly AI problem.
Further Reading & References
- Garner, Richard T.; Bernard Rosen (1967). Moral Philosophy: A Systematic Introduction to Normative Ethics and Meta-ethics. New York: Macmillan. pp. 215
- Metaethics in the Stanford Encyclopedia of Philosophy