"A Defense of Abortion" is a moral philosophy paper by Judith Jarvis Thomson first published in 1971. Granting for the sake of argument that the fetus has a right to life, Thomson uses thought experiments to argue that the fetus's right to life does not trump the pregnant woman's right to control her own body and its life-support functions, and that induced abortion is therefore not morally impermissible. Her argument has many critics on both sides of the abortion debate, yet continues to receive defense. Thomson's imaginative examples and controversial conclusions have made "A Defense of Abortion" perhaps "the most widely reprinted essay in all of contemporary philosophy".
Thomson says that you can now permissibly unplug yourself from the violinist even though this will cause his death: this is due to limits on the right to life, which does not include the right to use another person's body, and so by unplugging the violinist you do not violate his right to life but merely deprive him of something—the use of your body—to which he has no right. "[I]f you do allow him to go on using your kidneys, this is a kindness on your part, and not something he can claim from you as his due."
For the same reason, Thomson says, abortion does not violate the fetus's legitimate right to life, but merely deprives the fetus of something—the non-consensual use of the pregnant woman's body and life-support functions—to which it has no right. Thus, by choosing to terminate her pregnancy, Thomson concludes that a pregnant woman does not normally violate the fetus's right to life, but merely withdraws its use of her own body, which usually causes the fetus to die.
Thomson criticizes the common method of deducing a woman's right to abort from the permissibility of a third party committing the abortion. In almost all instances, a woman's right to abortion may hinge on the doctor's willingness to perform it. If the doctor refuses, then the woman is denied her right. To base the woman's right on the accordance or refusal of a doctor, she says, is to ignore the mother's full personhood, and subsequently, her rights to her body. Thomson presents the hypothetical example of the 'expanding child':
Thomson concedes that a third party indeed cannot make the choice to kill either the person being crushed or the child. However, this does not mean that the person being crushed cannot act in self-defense and attack the child to save his or her own life. To liken this to pregnancy, the mother can be thought to be the house, the fetus the growing-child. In such a case, the mother's life is being threatened, and the fetus is the one who threatens it. Because for no reason should the mother's life be threatened, and also for no reason is the fetus threatening it, both are innocent, and thus no third party can intervene. But, Thomson says, the person threatened can intervene, by which justification a mother can rightfully abort.
Continuing, Thomson returns to the 'expanding child' example and points out:
If we say that no one may help the mother obtain an abortion, we fail to acknowledge the mother's right over her body (or property). Thomson says that we are not personally obligated to help the mother but this does not rule out the possibility that someone else may act. As Thomson reminds, the house belongs to the mother; similarly, the body which holds a fetus also belongs to the mother.
To illustrate an example of pregnancy due to voluntary intercourse, Thomson presents the 'people-seeds' situation:
Here, the people-seeds flying through the window represent conception, despite the precautionary mesh screen, which functions as contraception. The woman does not want a people-seed to root itself in her house, and so she even takes the measure to protect herself with the best mesh screens, and then voluntarily opens the windows. However, in the event that one people-seed finds its way through her window screens, unwelcome as it may be, does the simple fact that the woman knowingly risked such an occurrence when opening her window deny her the ability to rid her house of the intruder? Thomson notes that some may argue the affirmative to this question, claiming that "...after all you could have lived out your life with bare floors and furniture, or with sealed windows and doors". But by this logic, she says, any woman could avoid pregnancy due to rape by simply having a hysterectomy - an extreme procedure simply to safeguard against such a possibility. Thomson concludes that although there may be times when the fetus does have a right to the mother's body, certainly in most cases the fetus does not have a right to the mother's body. This analogy raises the issue of whether all abortions are unjust killing.
Thomson does not support unlimited abortion rights. She gives as an example a hypothetical woman who seeks a late-term abortion "just to avoid the nuisance of postponing a trip abroad" and declares this to be "positively indecent".
Thomson also explicitly rejects the claim that pregnant women have a right to kill their offspring. She argues for the right of the mother to stop being pregnant, even if this results in the death of the offspring, but not for the right to ensure that the offspring is dead. If, for example, a late-term abortion accidentally results in the birth of a living baby, then Thomson would conclude that the mother has no right to kill the baby.
Critics of Thomson's argument generally grant the permissibility of unplugging the violinist, but seek to block the inference that abortion is permissible by arguing that there are morally relevant differences between the violinist scenario and typical cases of abortion. One notable exception to this general agreement is Peter Singer, who says that, despite our intuitions, a utilitarian calculus implies that one is morally obliged to stay connected to the violinist.
The most common objection is that Thomson's violinist argument can justify abortion only in cases of rape. In the violinist scenario, the woman was kidnapped: she did not consent to having the violinist plugged in and she did nothing to cause the violinist to be plugged in, just as a woman who is pregnant due to rape did nothing to cause her pregnancy. But in typical cases of abortion, the pregnant woman had intercourse voluntarily, and thus has either tacitly consented to allow the fetus to use her body (the tacit consent objection), or else has a duty to sustain the fetus because the woman herself caused the fetus to stand in need of her body (the responsibility objection). Other common objections turn on the claim that the fetus is the pregnant woman's child, whereas the violinist is a stranger (the stranger versus offspring objection), or that abortion directly and intentionally kills the fetus, whereas unplugging the violinist merely lets him die of natural causes (the killing versus letting die objection).
Defenders of Thomson's argument reply that the alleged disanalogies between the violinist scenario and typical cases of abortion do not matter, either because the factors that critics appeal to are not genuinely morally relevant, or because those factors are morally relevant but do not apply to abortion in the way that critics have claimed. Thomson's defenders also point to her 'people-seeds' argument as a strong analogy to typical cases of abortion.
Thomson's article, by positing a moral justification for abortion even if one grants a fetal right to life, opened up a new avenue in the philosophical debate about the ethics of abortion. Critics of her view have formulated many objections to her argument, and defenders have responded in kind in a back and forth that continues in philosophy journals even now.