 Metaethics steps back from moral theorizing to ask about the nature and function of morality. While first-order ethics seeks to explain what we should do, metaethics seeks to explain the status of those theories themselves: what are their metaphysical commitments, and what evidence do we have for or against them? Which epistemology best characterizes our moral practices? What is the correct semantics for moral language? These questions might not seem obviously empirical, but insofar as it attempts to give an account of moral semantics, epistemology, and ontology, metaethics aims, in part, to capture or explain what we do when we engage in moral talk, judgment, and evaluation. To the extent that metaethics sees itself as characterizing our ordinary practice of morality, it is therefore answerable to empirical data about that practice. To the extent that a theory claims that we are mistaken or in widespread error about the meaning of moral language, or that we lack justification for our core moral beliefs, this is taken to be a strike against that theory. For example, relativism is often criticized on the grounds that it requires us to give up the (putatively) widespread belief that moral claims concern objective matters of fact and are true or false independently of our beliefs or attitudes. We have already seen several ways that experimental data bears on theories about moral reasons (the debate between internalists and externalists) and the epistemology of moral judgment (the debate over the role of intuitions). In this section we will examine experimental contributions to the debate over moral realism, arguments about moral disagreement, and moral language.