  Although this naturalist reading of the Republic is not anachronistic—Aristotle and the Stoics develop related naturalist approaches, and Plato had naturalist contemporaries in a hedonist tradition—Plato himself would not be content to ground his account of good actions on empirical facts of human psychology. On his view, actions are good because of their relation to good agents, and agents are good because of their relation to goodness itself. But goodness itself, the Good, transcends the natural world; it is a supernatural property. This commits Plato to a non-naturalist version of ethical realism, which modernity’s creeping tide of naturalism threatens to wash away. But non-naturalism in ethics will retain some appeal insofar as the other ways of trying to explain our experiences of the moral life fail to answer the serious objections they face.