A third kind of pro-choice response is to invoke another principle, which conflicts with the pro-life principle against killing. Pro-choice liberals often emphasize two such principles: one about the rights of the pregnant woman to control her own body and another about overall human welfare. We will focus for now on human welfare.
Defenders of abortion often argue that abortion can sometimes be justified in terms of the welfare of the woman who bears the fetus, or in terms of the welfare of the family into which it will be born, or even in terms of the wel- fare of the child itself (if it were to be born with a severe disability or into an impoverished situation). This argument, when spelled out, looks like this:
(1) An action that best increases overall human welfare is not morally wrong.
(2) Abortion is sometimes the best way of increasing overall human welfare.
(3) Abortion is sometimes not morally wrong.
What are we to say about this argument? It seems valid in form, so we can turn to the premises themselves and ask whether they are acceptable. The first (and leading) premise of the argument is subject to two immediate criticisms. First, it is vague. Probably what a person who uses this kind of argument has in mind by speaking of human welfare is a certain level of material and psy- chological well-being. Of course, this is still vague, but it is clear enough to make the premise a target of the second, more important, criticism: Although maximizing human welfare may, in general, be a good thing, it is not the only relevant consideration in deciding how to act. For example, it might be true that our society would be much more prosperous on the whole if 10 percent of the population were designated slaves who would do all the menial work. Yet even if a society could be made generally happy in this way, most people would reject such a system on the grounds that it is unfair to the slave class.