Shortly before he died, Plenty Coups, the last great Chief of the Crow Nation, told his story--up to a certain point. "When the buffalo went away the hearts of my people fell to the ground," he said, "and they could not lift them up again. After this nothing happened." It is precisely this point--that of a people faced with the end of their way of life--that prompts the philosophical and ethical inquiry pursued in Radical Hope. In Jonathan...