Moral functionalism holds that the essence of a moral judgment is its function of encouraging or discouraging moral actions. It is distinct from other metaethical theories, such as moral realism and emotivism. It is more effective than moral realism and error theory in preventing moral agents from committing morally wrong acts. In addition, it is immune to, while other metaethical theories are vulnerable to, the objection that we know better than do others about our own mental states.