Judith Jarvis Thomson

Quick Facts

• Full name: Judith Jarvis Thomson
• Lived: 1929-2020
• Home base: United States, especially MIT
• Main fields: moral philosophy, rights theory, applied ethics, and analytic philosophy
• Best known for: "A Defense of Abortion," the violinist argument, and modern trolley problems
• Central concern: what one person may do to another person, even for a very good outcome

The Big Question

Thomson asked: when does a person's right block what would otherwise produce the best result?

Suppose five people will die unless one person is made to bear a terrible cost. Does the number five automatically settle the issue? Thomson's answer is no. Numbers matter, but they do not erase the separate claims of the person who would be used, injured, or killed.

In One Minute

Judith Jarvis Thomson was an American moral philosopher who made difficult ethical problems sharp by turning them into carefully built cases. She started with examples that forced a principle to show what it really meant.

Her most famous essay, "A Defense of Abortion," argues that even if a fetus is granted a right to life, it does not follow that a pregnant person must let the fetus use her body. The violinist example makes the point. If you wake up connected to a sick violinist whose life depends on your kidneys, it may be generous to stay connected, but he does not have a right to your body.

She also made the trolley problem central to modern ethics. For Thomson, these cases tested killing, letting die, redirecting harm, using someone as a tool, and the limits of moral arithmetic.

What They Taught

Thomson taught that morality is not just about adding up good and bad results. It is also about what may be demanded from particular people.

A right, for Thomson, is a claim that places duties on others. If you have a right over your own body, other people need a special justification before they may use it. Rights mark moral boundaries around persons.

Her most famous move in "A Defense of Abortion" is to grant an opponent's strongest premise and then ask whether it proves enough. Suppose, she says, that the fetus is a person with a right to life. Even then, the argument is unfinished. A right to life does not normally include a right to use someone else's body without consent. If the only way to keep someone alive is to force another person to serve as life-support, we still have to ask whether that use is owed.

This is why the violinist case became famous. You wake up in a hospital. A society of music lovers has kidnapped you and connected your kidneys to a famous violinist. He will die if you unplug, but he will recover after nine months if you stay. Thomson's point is not that the violinist is worthless. The point is that his right to life does not automatically give him a right to your organs, time, health, and confinement.

This leads to a distinction she used again and again: something can be morally admirable without being morally required. Staying connected to the violinist might be generous. But if you may unplug, then staying is not a duty.

She also argued that permission to defend oneself does not always depend on blame. Imagine a person is falling toward you through no fault of his own, and his body will crush you. He is innocent, but he is still a threat. Thomson asks whether you may protect yourself from an innocent threat.

Her trolley work asks when one person may be harmed to save others. Many people think a bystander may flip a switch so a runaway trolley kills one worker instead of five. Many also think the bystander may not push a large man from a bridge to stop the trolley, even though that would also save five. Thomson pressed the hard question: what is the moral difference?

Thomson did not deny that consequences matter. Saving five lives instead of one is a morally serious fact. But she rejected the idea that better totals automatically settle what may be done. Consequences have to be considered alongside consent, agency, bodily use, responsibility, and the rights of the person who would be made to pay the cost.

Her style is simple but demanding: describe the case clearly, define the claim, and ask whether the conclusion really follows.

Key Ideas With Examples

• Violinist argument: a thought experiment showing that a right to life is not automatically a right to use another person's body. The violinist may need your kidneys, but need is not the same as entitlement.
• Bodily autonomy: control over what happens in and to one's body. For Thomson, a body is not a public rescue tool that others may commandeer whenever the stakes are high.
• Moral permissibility: what morality allows. If you may unplug from the violinist, unplugging is permissible, even if staying connected would be kinder.
• Trolley problem: cases about whether it is permissible to harm one person to save several others. Flipping a switch and pushing a person can have the same body count but differ in agency and rights.
• Doing harm vs allowing harm: doing harm actively brings about injury; allowing harm lets danger continue. Thomson's bystander case tests whether this distinction alone can explain our judgments.
• Using someone as a means: making a person into the tool by which an outcome is achieved. Pushing a person into the trolley seems wrong partly because the rescue works through his body.
• Innocent threat: someone who endangers you without being guilty. A falling person may be innocent, but if he will crush you, your defensive permission may not depend on blame.

Major Works

• "A Defense of Abortion" (1971): Thomson's best-known essay. It argues that abortion can be permissible even if the fetus is treated as a person with a right to life. The violinist case shows why bodily use and consent are separate issues from the value of life.
• "Killing, Letting Die, and the Trolley Problem" (1976): tests whether the difference between killing and letting die can explain why some life-saving harms seem allowed and others do not.
• "The Trolley Problem" (1985): gives the problem much of its modern shape by comparing the switch case with the footbridge case.
• Rights, Restitution, and Risk (1986): collects essays on rights, compensation, liability, risk, and permissible harm.
• The Realm of Rights (1990): her most systematic book on rights. It asks what makes a right real and how rights can conflict.
• Moral Relativism and Moral Objectivity (1996, with Gilbert Harman): a debate-style book in which Thomson defends moral objectivity against Harman's relativism.
• Goodness and Advice (2001): examines goodness, reasons, and advice, asking how value connects to what a person should do.

Why It Matters

Thomson changed the way philosophers talk about applied ethics. She showed that a precise thought experiment can reveal which hidden premise an argument depends on.

Her abortion essay shifted attention from only asking "Is the fetus a person?" to also asking "What may one person require of another person's body?" That change did not end the debate, but it forced both sides to discuss consent, bodily use, responsibility, and the difference between killing someone and refusing life-sustaining aid.

Her trolley work became a testing ground for moral theory, law, psychology, and public policy. People now use trolley cases to discuss medical triage, autonomous vehicles, wartime targeting, and emergency rescue.

She also helped make rights theory concrete. Instead of treating rights as slogans, she asked what each right permits and forbids.

Proponents, Critics, and Opponents

Thomson worked within analytic philosophy. Her method was close reading of cases, careful distinctions, and pressure on unclear principles.

She developed the trolley problem from work by Philippa Foot, who used runaway trolley cases while thinking about abortion, killing, and double effect. Double effect says that intentionally causing harm can be morally different from foreseeing harm as a side effect. Thomson accepted the importance of intention, but she did not think a simple formula solved the cases.

Her attention to intention overlaps with Elizabeth Anscombe. She also resembles Immanuel Kant when she resists treating persons as mere tools, but she does not build her view from Kant's system of reason.

Critics of the violinist argument say pregnancy is not close enough to kidnapping. They argue that parenthood, consensual sex, fetal dependence, or the difference between a stranger and one's child changes the moral situation. Others say abortion involves killing in a way unplugging from the violinist does not.

Utilitarianism is another pressure point. A utilitarian wants the action with the best overall outcome. Thomson's cases show why many people think rights can block that arithmetic. Peter Singer presses impartial consequences more strongly than Thomson does. John Stuart Mill defends rights through utility, while Thomson tests rights through cases. Ronald Dworkin is a useful comparison because he also treats rights as limits on social goals.

Related Pages

• Philippa Foot
• Elizabeth Anscombe
• Utilitarianism
• John Stuart Mill
• Immanuel Kant
• Ronald Dworkin
• Peter Singer
• Analytic Philosophy