"[I]f you do allow him to go on using your kidneys, this is a kindness on your part, and not something he can claim from you as his due." For the same reason, Thomson says, abortion does not violate the fetus's legitimate right to life, but merely deprives the fetus of something—the non-consensual use of the pregnant woman's body and life-support functions—to which it has no right.
Thus, by choosing to terminate her pregnancy, Thomson concludes that a pregnant woman does not normally violate the fetus's right to life, but merely withdraws its use of her own body, which usually causes the fetus to die.
However, in the event that one people-seed finds its way through her window screens, unwelcome as it may be, does the simple fact that the woman knowingly risked such an occurrence when opening her window deny her the ability to rid her house of the intruder?
Thomson notes that some may argue the affirmative to this question, claiming that "...after all you could have lived out your life with bare floors and furniture, or with sealed windows and doors".
[If he is unplugged from you now, he will die; but] in nine months he will have recovered from his ailment, and can safely be unplugged from you.
Thomson says that you can now permissibly unplug yourself from the violinist even though this will cause his death: this is due to limits on the right to life, which does not include the right to use another person's body, and so by unplugging the violinist you do not violate his right to life but merely deprive him of something—the use of your body—to which he has no right.
In such a case, the mother's life is being threatened, and the fetus is the one who threatens it.
Because for no reason should the mother's life be threatened, and also for no reason is the fetus threatening it, both are innocent, and thus no third party can intervene.
If the doctor refuses, then the woman is denied her right.
To base the woman's right on the accordance or refusal of a doctor, she says, is to ignore the mother's full personhood, and subsequently, her rights to her body.