The document discusses several concepts in metaethics, including ethical naturalism, moral intuitionism, non-cognitivism, and moral realism. It also discusses the ideas of supervenience, universalizability, and the role of moral principles. Key concepts are ethical naturalism, which defines value in terms of natural facts; moral intuitionism, which holds moral facts are discovered through intuition; and non-cognitivism, which claims moral judgments do not have truth values but express attitudes.