In what way does Judith Jarvis Thompson's argument contribute to the abortion debate?

Judith Jarvis Thompson, through the use of analogy, argues that abortion is morally permissible, but only in three certain cases. These cases are 1) if the mother has been raped, 2) if contraception was used during intercourse and 3) if the mother's life is at risk. What is different about her argument is that, unlike conventional arguments for and against abortion, it does not centre around the question of whether or not the foetus is a person. Thompson claims that the foetus is a person, but argues that despite this, we can still allow a woman to have an abortion.

She argues this from the basis that the mother has a right to self defence. The most famous analogy she uses is the famous violinist. She asks us to suppose that we wake up one morning and discover that we are in a hospital bed and attached to a famous violinist. We are told that the famous violinist has a fatal kidney ailment, and that we must remain attached to the violinist for 9 months until they get better. Thompson then asks us if we think that we have a right to detach ourselves from the violinist. Most people, she claims, would say that it is absurd to expect us to remain attached to the violinist for 9 months. Thompson then goes on to argue that this is no different from pregnancy, and if the mother wishes to abort the foetus, on the basis of self defence, she should be allowed to.