The belief on the left that human nature can be changed at will, and the belief on the right that morality rests on God’s endowing us with an immaterial soul, are becoming rearguard struggles against the juggernaut of science. A popular bumper sticker in the 1990s urged, QUESTION AUTHORITY. Another bumper sticker replied, QUESTION GRAVITY. All political philosophies have to decide when their arguments are turning into the questioning of gravity.
