unplugging the baby
The pro-life argument is pretty basic. It goes like this:
1. It's wrong to take the life of an innocent human being.
2. Abortion takes the life of an innocent human being.
3. Therefore, it's wrong to have an abortion.
Most people will already agree with the first premise, so the whole argument between pro-life people and pro-choice people revolves around the second premise.
As an aside, most pro-choice arguments suffer from irrelevence, because they don't address the second premise.
Suppose, though, that a pro-choice person agrees with the second premise (as some do), but still insist that women have a right to an abortion on the basis that a woman has sovereinty over her own body, and the unborn in her womb has no right to use her body without her consent. The argument would look like this:
4. A woman has a right to sovereignty over her own body.
5. Abortion involves the excercise of a woman's sovereignty over her own body.
6. Therefore, a woman has a right to have an abortion.
She dispute (1) on the basis that there is an exception that applies to all abortions. She would say that it's wrong to take the life of an innocent human being unless that being depends on the use of your body to survive. So she has rebutted the pro-life argument and constructed a pro-choice argument of her own. What do you do in a situation like that?
Well, you could dispute her first premise the same way she disputed yours. She disputed yours by finding an exception to it that applied to all abortions. You could dispute her first premise by finding an exception that applies when it involves another human life. Here's an analogy to explain.
Let's say a woman has an infant who is still breast-feeding. There's no such thing as formula, and nobody is willing to breast-feed the baby for her. Would she have the right to starve the baby to death on the basis that she has sovereignty over her own body? You see, the baby needs her body to survive.
If you say that she has an obligation to breast-feed, then that would require an exception to (4) that would exclude abortions from a woman's right to sovereignty over her own body. Since (4) was the basis for finding an exception to (1), the pro-life argument is once again intact.
I was arguing with a friend of mine about abortion, and when I used this analogy, she surprised me. She said the woman would have a right to let her baby starve, because she is under no obligation to let her baby use her breast to stay alive. At that point, I was stumped. I didn't know where to go from there.
Notice that my analogy is similar to the famous violinist analogy Judith Thompson came up with. Both analogies are meant to be analogous to abortion, but clearly the breast-feeding analogy is more analogous than the violinist analogy, so I think it could probably be used as a defeater to the famous violinist analogy.