Is tribalism ― the political and cultural divisions between Us and Them ― an inherent part of our basic moral psychology? Many scientists link tribalism and morality, arguing that the evolved “moral mind” is tribalistic. Any escape from tribalism, according to this thinking, would be partial and fragile, because it goes against the grain of our nature. Dr. Allen Buchanan offers a counterargument: the moral mind is highly flexible, capable of both tribalism and deeply inclusive moralities, depending on the social environment in which the moral mind operates. Dr. Buchanan is a fellow of the Hastings Center and a professor of Philosophy of International Law at the Dickson Poon School of Law at King's College, London.