In her article "A Defence of Abortion," Thomson argues for the conclusion that even if we consider the unborn fetus a person, aborting a fetus is not wrong. Opponents of abortion, according to Thomson, spend too much time establishing that the fetus is a person and too little time arguing from the fact that a fetus is a person to the impermissibility of abortion. Thomson's reductio ad absurdum helps explain that abortion is permissible regardless of the status of the fetus. Here, I will draw out some main points of Thomson’s argument and provide some questions for discussion.
Before summarizing Thomson’s argument in favor of abortion, it might be helpful to review what Thomson believes opponents of abortion say. Opponents of abortion may argue as follows: (1) The fetus is a person from the moment of conception. (2) Every person has a right to life. (3) If every person has a right to life and the fetus is a person, then the fetus has a right to life. (4) Moreover, the mother possesses the right to decide what happens in and to her body. (5) A person’s right to life is stronger than the mother’s right to decide what happens in and to her body. (6) Therefore, if a person’s right to life is stronger than the mother’s right to decide what happens in and to her body and the fetus is a person (which follows from (1), (2), & (3)), then the fetus may not be aborted since a person’s right to life outweighs the mother’s right to decide what happens in and to her body.
She begins with a thought experiment, and she asks us to suppose that while sleeping we have been connected to a famous violinist. The famous violinist, who suffers from a rare blood disease for which our blood provides an antidote, will die if disconnected. Thomson believes that we have a right to disconnect ourselves since lying in bed with the famed violinist for an indefinite (or definite) period is too much for morality to demand. What this vivid example illustrates is that when our body is being used for the purpose of sustaining the violinist’s life, doing so infringes in some way upon our rights. There exists a clear distinction between the violinist’s right to life and the violinist’s right to use our body. Since the case of the violinist is similar to the case of the fetus, Thomson determines there is no reason one needs to remain attached to the fetus than to the famed violinist.
Her argument relies on the idea that it does not follow from one’s right to life to the notion that one has a right to use someone else’s body in order to preserve that right to life. If a human being has any right at all, then it would seem fair to assume that one has a “just, prior claim” to one’s own body. Accordingly, no one has any right to use any one else’s body unless that person, whose body is used, consents to the use of their body. To prove such a claim, Thomson introduces the Henry Fonda example. If I am suffering from a fatal virus that can be relieved by the “touch of Henry Fonda’s cool hand on my fevered brow” (Thomson 1971, p. 726), there is nothing I can do to force Henry Fonda to touch my “fevered brow” despite how easy it may be for him to do so. Thomson seems to argue only that “having a right to life does not guarantee having either a right to be given the use of or a right to be allowed continued use of another person’s body – even if one needs it for life itself” (Thomson 1971, p. 727).
The final part of Thomson’s paper tries to show that if the mother does not kill the fetus unjustly, then the mother does not violate the fetus’ right to life. No injustice would be done. Thomson asks us here to suppose that a woman voluntarily indulges in intercourse knowing full well that such an act may result in pregnancy. Although the act may result in pregnancy, the mother has no intention of becoming pregnant. According to Thomson, the fetus has the right to the use of the mother’s body only if her pregnancy resulted from a voluntary act. To support the argument, Thomson tells us of the case of the burglar. If one evening a person decides to leave a window open for ventilation and a burglar enters through the open window, then it would be absurd to believe that the one who left the window ajar is to blame for the burglar entering the window. Thomson does not seem to defend the permissibility of abortion, but she does seem to argue that the mother’s right to decide what happens in and to her body take precedence over the fetus’ right to life.
Despite Thomson’s judicious treatment of the issues surrounding abortion, some questions remain. First, with regard to the use of the violinist example, is the comparison of the violinist to a fetus an accurate one? Likewise, is the manner in which the violinist connected to another person significantly different from the manner in which one becomes pregnant and does this create a problem for Thomson’s use of this illustration? Second, although it is fair to assume that no one has a right to use someone else’s body without prior consent, does this fact entail the right to end someone else’s life in order to do what she wants with her body? Finally, does a defense of the right to choose what happens in and to one’s own body warrant the permissibility of abortion?