Leon R. Kass, M.D., P.h.D., is chairman of the President's Council on Bioethics. He is the Addie Clark Harding Professor in the Committee on Social Thought at the University of Chicago and Hertog Fellow in Social Thought at the American Enterprise Institute. Also the author of Toward a More Natural Science: Biology and Human Affairs, The Ethics of Human Cloning (with James Q. Wilson), and Life, Liberty, and the Defense of Dignity: The Challenge for Bioethics, he lives with his wife, Amy Apfel Kass, in TK.