Many Americans who believe that women should be able to choose when and whether to bear a child are also deeply disturbed by the one-and-one-half million abortions performed each year in this country. They regard these concerns as irreconcilable, because the topic of abortion, until now, has been framed as a black-or-white conflict between the rights of the mother and those of the fetus. The very idea of compromise or common cause draws scorn among...