A few years ago, I participated in a panel discussion at Princeton University with Peter Singer on the subject of abortion and animal rights. (Singer is a philosopher famous for his utilitarian approach to ethics, including his arguments in favor of euthanasia and infanticide.) My purpose that night was to try to persuade Singer and the other panelists (who were also animal rights advocates) to consider granting at least the same moral weight to a human embryo as they give animals and, in doing, to recognize that abortion kills a human being. To no one’s surprise, I didn’t convince them.