Metaethics
Metaethics can be described as the philosophical study of the nature of moral judgment. It is concerned with such questions as: Do moral judgments express beliefs or rather desires and inclinations? Are moral judgments apt to be assessed in terms of truth and falsity? Do moral sentences have factual meaning? Are any moral judgments true or are they systematically and uniformly false? Is there such a thing as moral knowledge? Are moral judgments less objective than, say, judgments about the shapes and sizes of middle-sized physical objects? Is there a necessary connection between moral judgments and motivation? Are moral requirements requirements of reason? Do moral judgments have a natural or non-natural subject matter? A useful way of starting on metaethics is to distinguish between realist and non-realist views of morality. Moral realists hold that moral judgments express beliefs, and that some of those beliefs are true in virtue of mind-independent moral facts. Opposition to moral realism can take a number of forms. Expressivists deny that moral judgments express beliefs, claiming instead that they express non truth-assessable mental states such as desires or inclinations. Error theorists and (revolutionary) fictionalists claim that moral judgments are systematically false. Response-dependence views of moral judgments allow that moral judgments express beliefs and that at least some of them are true, but hold that they are true in virtue of mind-dependent moral facts. Moral realism itself comes in many varieties: reductionist, non-reductionist, naturalist, non-naturalist, internalist, externalist, analytic, and synthetic.