P rofessor Charles Taylor’s heart aches for the Crow—the Crow Indians of the Yellowstone river valley, that is, whose warriors are now mere ghosts, and whose culture of incessant killing and scalping and murder and rapine has been irrevocably lost. “Tragically lost,” says Taylor, Professor of Law and Philosophy at Northwestern University. In his mind cultural loss is about the worst thing that can happen.

Genocide is even more serious, it’s true, but as he writes in last April’s New York Review of Books, reviewing Jonathan Lear’s Radical Hope: Ethics in the Face of Cultural Devastation, “The issue is not genocide. Many of the Crow people survive; but their culture is gone.” He then quotes the tribal chief Plenty Coups who said back in the 1920s that “When the buffalo went away the hearts of my people fell to the ground, and they could not lift them up again. After...