Ethical naturalism holds that ethical facts about such matters as good and bad, right and wrong, are part of a purely natural world — the world studied by the sciences. It is supported by the apparent reasonableness of many moral explanations. It has been thought to face an epistemological challenge because of the existence of an “is-ought gap”; it also faces metaphysical objections from philosophers who hold that ethical facts would have to be supernatural or “nonnatural,” sometimes on the grounds (...) that ethical thought has a practical role that no thought about purely natural facts could have. Its defenders have argued resourcefully against these challenges. (shrink)