The Violinist Analogy
Following the argumentative structure just described, Judith Thomson’s philosophical defence of abortion begins by granting, for the sake of argument, that the fetus is a person from conception. Her main argument is then introduced using an imaginary scenario:
You wake up in the morning and find yourself back to back in bed with an unconscious violinist. A famous unconscious violinist. He has been found to have a fatal kidney ailment, and the Society of Music Lovers has canvassed all the available medical records and found that you alone have the right blood type to help. They have therefore kidnapped you, and last night the violinist’s circulatory system was plugged into yours, so that your kidneys can be used to extract poisons from his blood as well as your own. The Director of the hospital now tells you, ‘Look, we’re sorry the Society of Music Lovers did this to you—we would never have permitted it if we had known. But still, they did it, and the violinist is now plugged into you. To unplug you would be to kill him. But never mind, it’s only for nine months. By then he will have recovered from his ailment, and can safely be unplugged from you.’ Is it morally incumbent on you to accede to this situation? No doubt it would be very nice of you if you did, a great kindness. But do you have to accede to it? What if it were not nine months, but nine years, or longer still?
The scenario described is offered up as an analogy to unwanted pregnancy. But it is important to get clear on the precise position it is meant to rebuff. Thomson is refuting a particular way of thinking about the ethics of abortion once it is granted that a fetus is a person, which runs as follows. If every person has a right to life, and if the fetus is a person, then the fetus has a right to life. The pregnant woman also has the right to decide what will happen to her body. But the right to life is stronger than the right to bodily autonomy, and so outweighs it. Hence abortion is impermissible, even where pregnancy is a result of rape, and perhaps even where abortion is necessary to save the pregnant woman’s life. This is what Thomson dubs ‘the extreme view’.
But the step from assuming that the fetus is a person to the moral impermissibility of abortion is, on Thomson’s analysis, ‘neither easy nor obvious’. This is what the violinist analogy is meant to illustrate. If you agree, as Thomson believes you will, that you are allowed to unplug the violinist, then, by analogy, the ‘extreme view’ about abortion is thrown into doubt. The violinist is unquestionably a person, but you do not believe that this forbids you to unplug him from your body, even if that spells his death. Why does the same not hold for a pregnant woman and her fetus? Why can she not ‘unplug’ the fetus to free herself from the burdens of supporting its life with her own body?
In describing Thomson’s position, David Boonin stresses a key nuance.n Her claim, he says, is not that the woman’s bodily right simply trumps the fetus’s right to life. This indeed would be contrary to our very strong judgement that the right to life is more important than the right to control one’s own body. The argument is rather that the fetus’s right to life ‘does not include or entail the right to be provided with the use or the continued use’ of the woman’s body in order to go on livingd2 Thomson believes that unplugging the violinist does not violate his right to life to begin with, since he possesses only the right not to be killed unjustly, and unplugging him, even if it leads to his death, is not unjust. As Boonin explains, ‘even though he has a right to life ... he has no right to the use of your kidneys’.  Regarding abortion, then, Thomson is not attempting to persuade us that in any conflict between bodily autonomy and the right to life, bodily autonomy wins out, but that there is no such conflict in abortion, because the fetus’s right is not violated by termination of pregnancy.
Thomson’s analysis of pregnancy and abortion is brought into sharper focus by her driving claim that not unplugging the violinist in the situation she describes would be an act of a Good Samaritan. As she remarks, ‘it would be very nice of you’ if you allowed him the continued use of your kidneys, ‘a great kindness’, but not something you can possibly be required to dod4 Boonin regards Thomson’s analogical argument as just one example of the more general claim that ‘the woman’s carrying a pregnancy to term can be subsumed into the wider category of good samaritanism’, a claim introduced in chapter 1. How accurate this description of unwanted pregnancy is thought to be is therefore key to the success of the argument.
A crucial premise underpinning Thomson’s conclusion on the violinist’s—and, by implication, the fetus’s—entitlement to the use of another’s body for sustained life is that ‘we do not have any ... “special responsibility” for a person, unless we have assumed it, explicitly or implicitly’. 15 On her reckoning, the mere fact that you find yourself in a situation whereby another person, the violinist or the fetus, depends on the use of your body for very survival is not enough to ground such responsibility unless you have done something to accept it, at least tacitly. Importantly, Thomson does not regard simply being in a relationship of biological parenthood to the fetus as, without more, a foundation for any such responsibility.
It is noteworthy that the entire thrust of the Good Samaritan Thesis (GST) depicts the potential wrongness of abortion in a very particular way. That is, it suggests that if abortion did happen to be morally deviant, this would only be because it violates a positive duty to do something—to give aid to another. As with unplugging the violinist, the thesis supposes that abortion could only be, if anything, a wrongful refusal to save life.
In a different vein, Thomson also suggests that self-defence, or something like it, is a justification both for unplugging the violinist and for performing an abortion, particularly where the woman’s life is endangered by her pregnancy. Sometimes it is justifiable to kill another person if they present a serious enough threat. As Thomson argues, ‘however innocent the child may be, you do not have to wait passively while it crushes you to deathT6 Somewhat differently from the GST, this kind of reasoning categorizes abortion’s potential wrongness as a violation of a negative duty to refrain from harming others—a duty which can be superseded if the action is justified. If I kill an aggressor to defend my own life, self-defence legitimates what would otherwise be an infraction of the duty to avoid killing. This duty extends to anyone I might kill, as opposed to the duty to proffer positive assistance, which is often thought to extend only to particular individuals for whom I have special responsibility.
Translated into a legal framework, the violinist analogy reasoning implies that the law might, with coherence, recognize the personhood of the fetus whilst still declining to treat abortion as unlawful killing, either because it does not regard it as killing at all but only the legitimate refusal to be a Good Samaritan, or because if it is homicide, it has a legally recognized justification, like self-defence (another claim I introduced in chapter 1). I wish to concentrate here on the first argument, what I have been calling the Good Samaritan Thesis.