How we make moral judgments has been a concern of philosophers and psychologists for a long time. In the West, this history begins with the Greeks and their debates over “the good life”: the Sophists and Plato, the Stoics and the Epicureans. There is the Judeo-Christian tradition, with the Ten Commandments, Jesus’s summary of the Law, the Sermon on the Mount, and his “new commandment” that we love one another. The medieval period gave us Aquinas’s marriage of Platonic and Christian thought. The Enlightenment brought us Hobbes’s ethical naturalism, Hume’s utilitarianism, and Kant’s categorical imperative.