Last week Ryan Anderson wrote about a symposium at Princeton devoted to the question of whether ending early human life is wrong. He rightly called attention to the position of Princeton’s Elizabeth Harman, who argued that, “Things have moral status throughout their existence, just in case there’s any time in their existence at which they are conscious.” That is, a fetus has moral status even before it reaches consciousness if, and only if, it lives long enough to reach consciousness sometime later. Hence, if a fetus is aborted before it reaches consciousness, then it in fact never will reach consciousness and so never has moral status. Killing such a fetus is thus morally permissible. As Anderson puts it, Harman’s position occasioned much head scratching at the symposium.

I think I see, however, why this putative principle seems so puzzling. We need moral principles, first and foremost, to guide conduct. They tell us what we may do and what we may not do in certain cases. If the question is whether we may kill a certain human fetus, we want moral principles that will help us answer that question. Harman’s principle, however, comes to this: We may kill the fetus if, and only if, we actually do kill the fetus (thus ensuring that it is never conscious). If we were to try to use this principle to determine whether we should kill some particular fetus, we would thus first have to know whether, in fact, we actually will kill it. But we will kill it only if we first decide we may kill. Hence, to use Harman’s principle to decide whether we may kill a certain fetus, we would first have to know whether we may kill that fetus. This makes the principle useless for guiding conduct and thus no genuine moral principle at all.