Judith Thomson, “A Defense of Abortion”

Posted: Wed, Sep 10, 2025

Thomson’s thesis: Even if the fetus is a person from the moment of conception, abortion is still (for the most part) morally permissible.

Thomson’s intervention

Thomson’s argument is meant to move the battle line: “Pro-choice” vs. “pro-life” as a conceptual frame obscures the issue.

Here’s how the argument against abortion usually goes:

  1. A fetus is a person from [point X].
  2. Every person has a right to life.
  3. Therefore, abortion is morally impermissible from [point X].

Thomson observes that (3) does not follow without an implicit extra premise:

The fetus’s right to life is overriding.

This premise is not obviously true: Even those against abortion do not typically think that the fetus’s right to life overrides the pregnant person’s right to life.

Thomson’s innovation is to argue that the fetus’s right to life does not even override the pregnant person’s right to decide what happens in and to their body.

The violinist case (pp. 48–49)

In-class activity: How does Thomson use the violinist case to defend abortion? Do you feel she is successful?

Thomson’s claim: There is no morally relevant difference between disconnecting yourself from the violinist and terminating your pregnancy.

  • Her diagnosis: The right to life does not entail a right not to be killed (simpliciter), only a right not to be killed unjustly. (Note the case-to-theory methodology!)
  • Worry about a disanalogy: The violinist case deals with kidnapping. Does the argument justify merely a rape exception for abortion?
    • Thomson’s reply: The kidnapping setup is morally irrelevant. “Surely the question of whether you have a right to life at all, or how much of it you have, shouldn’t turn on the question of whether or not you are the product of a rape” (p. 49).
    • The burglar and the people-seeds examples (pp. 58–59).