Ethical Theory Spring 2022

Thomson’s Argument


We will talk about problems facing Thomson’s argument about abortion.

The first problem concerns the violinist case. In the violinist case, “you” are kidnapped and hooked up to the violinist. But most, though not all, pregnancies are not the result of non-consensual actions like kidnapping. That appears to be an important difference.

The second problem concerns Thomson’s attempts to distinguish between things that people should do for one another and things that they must do.


Our question is what the right to life gives a person a right to have. Thomson’s proposal is that it gives you the right not to be killed unjustly. That’s not incredibly helpful. Now we’re asking “what makes a killing unjust?” It is not obvious that this is going to be easier to answer than “what does the right to life give you a right to have?”

However, Thomson has identified a class of acts that she thinks are clearly unjust. So we can start from there and see how far we get by comparing them with abortion. Thomson thinks that it is unjust to go back on voluntary transfers of rights. To illustrate what a transfer of rights is, suppose that I give you my pencil. This is not a loan; my gift makes the pencil yours. Thomson thinks it would be unjust if I were to take the pencil from you after having done that.

So we have one example of the kind of act that would be unjust, at least, according to Thomson. As it happens, this seems to line up nicely with the major problem that her argument faces. Her argument relies on an analogy between the violinist case and abortion. The person connected to the violinist was kidnapped. Most cases of abortion are the results of voluntary behavior and not anything violent or coercive like kidnapping. That appears to be an important difference. And Thomson’s remarks about injustice seem to explain why it would be an important difference. If the woman who wants an abortion had voluntarily given the fetus a right to use her body, then it would be unjust to take it away. There is nothing resembling a voluntary surrender of rights in the violinist case and so it does not appear to be a case of injustice.

Let’s start there.

Suppose we are talking about a pregnancy that is the result of voluntary intercourse. And suppose that there was an attempt to avoid pregnancy by using some form of normally reliable birth control. There is clearly a voluntary act that leads to the pregnant woman being attached to a fetus. But do we count this as voluntarily giving the fetus the right to use her body?

It’s not easy to say. We need to talk about this.

One thing that I believe after having taught this article for a long time is that the question is probably not framed in a helpful way. The question, to remind you, is whether the pregnant woman who wants an abortion may not have one because she voluntarily gave the fetus the right to use her body. If so, Thomson believes, having an abortion would be an unjust killing and so a violation of the fetus’s right to life; if not, then it isn’t an unjust killing and it isn’t a violation of the fetus’s right to life.

This way of putting it seems off to me for two reasons. First, the fetus isn’t there to be given the right to use the mother’s body. When the relevant voluntary action occurs, the fetus doesn’t exist and so it can’t be the recipient of a transfer of rights. Second, transfers of rights normally have to be done intentionally. You can be liable for harms you inadvertently cause but you usually have to intend to transfer your rights in order to do so.

It’s possible that the reason why we’re unsure of what to say about the voluntariness point is that Thomson’s way of framing it as a question about transfers of rights does not really get to the heart of the point. I suspect that we might find it more fruitful to think about cases in tort law rather than those involving property. But that’s just a guess.

Should and must

Once we are satisfied with our discussion of the voluntariness point, we will take up a different question. What are people required to do for others?

Thomson thinks that there could be cases where it would be indecent to unplug yourself from the violinist even if the violinist has no right to use your body.

We surely must all grant that there may be cases in which it would be morally indecent to detach a person from your body at the cost of his life. Suppose you learn that what the violinist needs is not nine years of your life, but only one hour: all you need do to save his life is to spend one hour in that bed with him. Suppose also that letting him use your kidneys for that one hour would not affect your health in the slightest. Admittedly you were kidnapped. Admittedly you did not give anyone permission to plug him into you. Nevertheless it seems to me plain you ought to allow him to use your kidneys for that hour-it would be indecent to refuse. (Thomson 1971, 59–60)

It seems to me that at this point the topic subtly shifts from the right to life to the right to abortion. You might not have the right to unplug the violinist even if he does not have the right to use your body. That’s important! While we started with the right to life, what we really want to know is whether there is a right to abortion. In my opinion, this is where she tackles that question most directly.

Thomson approaches the question by looking at two cases: minimally decent samaritanism, which is mandatory, and good samaritanism, which is praiseworthy but not required.

Her point is that the things we require people to do for others do not come close to the cost of nine months of pregnancy plus the emotional costs of either raising a child or putting one up for adoption. She does not know exactly where the line between minimally decent samaritanism and good samaritanism falls, but she is sure that pregnancy is far from the line on the optional, good samaritan side. This is less of an argument than a question: why should pregnancy be the only exception?

Key Points

These are the things you should know or have an opinion about from today’s class.

  1. Why the violinist case seems to be different from most abortion cases.
  2. The difference between good samaritanism and minimally decent samaritanism.


Thomson, Judith Jarvis. 1971. “A Defense of Abortion.” Philosophy & Public Affairs 1 (1): 47–66.