Here’s a hypothetical. Suppose there are conjoined twins and they both share the same uterus. They get pregnant. Twin A wants an abortion but Twin B vehemently wants to keep the baby.
Which of these two twins has the greater moral/ethical right over the fetus that’s growing within them?
And if I can add, what about legal rights?
(And if you don’t believe such conjoined twins exist, look at this. The picture is not photoshopped)
Measures to induce an abortion - in fact, a wide range of medical treatments - would be an assault if performed without consent. I would have thought that if either twin objects to an abortion (or other medical treatment) then that twin is assaulted if the abortion/treatment is nevertheless performed.
As for the moral case, moral principles about a woman’s right to autonomy over her own body (as a foundation for abortion) have to be modified to meet circumstances where that body is shared with another woman. In so far as they have a “right to choose”, both twins have an equivalent right to choose, and a choice not to have an abortion is just as much a choice as a choice to have one. It’s useless, therefore, to look to “right to choose”/autonomy arguments to resolve this dilemma. If anything, far from resolving the dilemma, in this instance they give rise to it.
I’d say if you had to pick one over the other, giving preference to the person who actually had the relations that resulted in the pregnancy would be the way to go.
What if the fetus needed a life-saving medical treatment to survive? The twin who doesn’t want the baby refuses the treatment.
(See this picture here, the doctors made an incision into the womb to perform a corrective spinal surgery on the fetus)
Although the incision into the uterus could be made on the other twin’s side of her body who wants the baby. Would that violate the other twin’s rights? Maybe the other twin is not innervated on that side of the body so she cannot feel anything.
Suppose they both engaged in intercourse (with the same man). So there is no way to be sure which one was actually the biological mother—not that it makes any real difference at all since both twins share identical DNA. Even supposing the twins each had separate and distinct ovaries (or maybe one ovary each, haha 
) it would still not really make any difference. Just because it happened to be your ovary that contributed the egg, does that therefore give you some sort of right? We can see how ridiculous and futile this is.
Let’s make this more interesting and have a side hypothetical for the moment. What if one of the twins was in a coma? The twin that is still conscious wants an abortion, but the unconscious twin was known to have been very active in the pro-life movement (i.e. it’s very likely she wouldn’t want an abortion).
Therefore you have only one woman that is capable of making a choice. Even though someone else’s rights are potentially at stake. Should she have the right to get an abortion?
And, is this hypothetical so different from a regular woman who’s having an abortion? Oh, something to think about there! 
Leaving aside the hypothetical 3 way, I’d still say the moral edge, if we must give it to one and not the other, goes to the woman who choose to have sex. Both would face identical situations if the pregnancy was the result of a rape and each woman had opposing desires about the fate of the pregnancy. But if the situation was one in which one woman of the pair decides to have sex while the other does not (and may not really even know the person), giving preference to the desires of the third wheel over the desires of the person having the sex itself (regardless of biology) seems wrong.
Or maybe one of the twins had passed out from drinking too much alcohol and the man had sex with both of them—for one it was rape, but for the other twin it was entirely consensual.
And suppose the conjoined twins body only had one vagina.
So if one of the women chose to have sex and the other didn’t, you think it would be okay to force the pregnancy on the twin who was sexually violated??
By that same logic couldn’t we also say that a rapist has the right to force his victim to have his baby because he was the one to choose sex and she didn’t? See how your argument sounds in that context?
Oh, and just because the sperm enters one of their vaginas (assuming they had two different reproductive tracts and just happened to have a conjoined womb) doesn’t mean it didn’t fertilize with an egg from the other twin. (if that matters at all to you)
Help me understand, I’m just not seeing this original consent to sex as the deciding factor.
Does one twin have a greater right to choose because they are choosing life (or choosing abortion) ?
In other words, the rights of each might not be equal because of what they are choosing. Maybe we as a society find it unconscionable to force one woman to undergo an abortion against her will, so that trumps the choice of the other woman. Or conversely, maybe you believe both twins have to consent for a baby to take up space inside their body, if one woman doesn’t want it it has to go.
If you hypothesize a pregnant singleton in a coma who is known to be strongly opposed to ever having an abortion in any circumstances, obviously it would be both illegal and immoral to induce an abortion.
I don’t see that this changes if she is a conjoined twin. You can’t impose an abortion on her, not even to vindicate her sister’s right to choose, since in doing so you would be frustrating her own right to choose.
What if the baby will grow up to be Hitler? What then, smart guy?
I just thought this was interesting because a lot of the same arguments that could be made in the case of conjoined twins could also apply in the case of regular pregnancy too.
Just thought this might shine an interesting perspective on the issue for some people.
This would definitely be one for the medical ethicists, that’s for sure.
I read somewhere about a pair of conjoined female twins who had clearly defined upper and lower bodies (IIRC, they were joined at the lower back) and each married separate men, a la Chang and Eng in reverse. One became pregnant, and both were able to nurse the baby. Even weirder is that the one who was pregnant did not have morning sickness, but the twin who wasn’t, did! :eek:
I think what it shines a light on is the limitation of “personal autonomy” arguments for decisions about a person’s body in the (fortunately very rare) cases where the person doesn’t have an autonomous body.
You could of course springboard from this and argue that the unborn child in a more conventional case is in some way meaningfully analogous to the conjoined twin in this case. And that would get you straight back into a very tired, very stale argument that’s been had before. So lets not do that.
When two equally involved people want different things, I would consider the default to be “don’t modify the status quo”. Therefore no abortion and no life-saving procedures for the embryo/fetus in a situation where one conjoined twin wanted to have the baby and the other wanted an abortion, and where one twin wanted life-saving but potentially invasive medical procedures to preserve the life of the fetus and the other did not.
That probably wouldn’t make either twin happy with me if I were the judge.
I don’t think splitting the twins is a workable solution either.
So, the pro-choice twin ingests an abortifacient, killing the fetus. Do you imprison her?
Another question, suppose conjoined twin #1 slips an abortion pill into twin #2’s food. Would that be any different? It’d basically be the same effect.
If the twins share a uterus, then I think we can hypothesise that they also share at least part of a digestive tract. So anything swallowed by either twin is ingested by both of them. Or, perhaps better, is ingested by their shared body.
If either twin takes poison, both twins are poisoned; if either twin takes drugs, both twins are drugged. If either twin drinks enough, both twins are drunk. And so forth.
As before, I don’t think the moral implications of this are greatly altered by the fact that the thing one of the twins wishes to consume is an abortifacient rather than some other substance. I think if you have a shared body, you don’t have the same degree of autonomy with respect to decisions about how to treat that body.
Would I jail the twin who took the abortificient, thereby administering it to the other twin? No, of course not, since I couldn’t do that without jailing the other twin as well. While intentionally administering an abortifacient to a pregnant woman who doesn’t want an abortion is a very serious matter, the unusual circumstances of this case clearly preclude a custodial sentence.
