A defender of abortion might reply in a number of ways. Some theory of fairness might be developed to argue that many abortions are not unfair to the fetus, because the fetus has no right to use the pregnant woman’s body. (See the reading from Thomson, page 446.) The burden of the argument may shift to the question of whether or not a human fetus is a person and therefore possessed of a right to fair treatment. It might also be argued that questions of human welfare are sometimes more important than issues of fairness. During war and some emergencies, for example, members of a certain segment of the population are called on to risk their lives for the good of the whole in ways that might seem unfair to them.
When the argument is put on this new basis, the question becomes this: Are there circumstances in which matters of welfare become so urgent that the rights of the fetus (assuming the fetus has rights) are overridden? The obvious case in which this might happen is when the life of the bearer of the fetus is plainly threatened. For many conservatives on abortion, abortion is permitted in such cases. Some who hold a pro-choice position will maintain that severe psychological, financial, or personal losses to the pregnant woman may also take precedence over the life of the fetus. Fur- thermore, if not aborted, many fetuses would live in very deprived cir- cumstances, and some would not develop very far or live very long, because they have deadly diseases, such as Tay-Sachs. How severe must these losses, deprivations, and diseases be? From our previous discussion of slippery-slope arguments in Chapter 13, we know that we should not expect any sharp lines here. Indeed, people will tend to be spread out in their opinions along a continuum ranging from a belief in complete pro- hibition to no prohibition.
Using the method for reconstructing arguments, we now have a fairly clear idea of the main options on the abortion issue. But understanding the struc- ture of the debate—though essential for dealing with it intelligently—does not settle it. If the reasons on all sides are fully spelled out and disagreement remains, what is to be done?
At this stage, those who do not simply turn to abuse often appeal to ana- logical arguments. The point of an analogical argument is to reach a conclu- sion in a controversial case by comparing it to a similar situation in which it is clearer what is right or wrong. In fact, a great deal of ethical reasoning uses such analogies. We have already seen one simple analogy between an abortion to save the life of the mother and self-defense against an insane person. To get a better idea of how analogical reasoning works in ethics, we will concentrate on a more complex analogy, which raises the issue of whether abortion is morally permissible in cases of pregnancy due to rape.