A little-discussed aspect of the “conservative” position on abortion involves the claim that human beings exist at all stages of gestation — that even the human fertilized ovum (zygote) is a human being. There are good reasons of both a practical and theoretical nature why this particular idea has received so little attention in the abortion controversy. On the practical side there is the fact that zygotes are rarely if ever the subjects of abortion decisions; and on the theoretical side, there is the prima facie implausibility of the idea itself — an implausibility stemming from the fact that human zygotes possess none of the features that distinguish clear-cut examples of human beings from other living things.
I would like to suggest, however, that there are good reasons — again both practical and theoretical — for examining with some care the idea that human zygotes are human beings. For even if this idea is not central to the abortion controversy, it has clear relevance to the morality of using intrauterine devices (I.U.D.'s) as a means of procreation control.