In a previous post, I provided my response to a thought experiment posed by Patrick S. Tomlinson, which he claimed no pro-life person had ever answered honestly, in ten years. In this post, I would like to put forward a thought experiment of my own, which has never been answered by a pro-choice person, that I am aware of. I would love it if any readers wanted to answer it!
When considering the ethics of abortion, it’s not enough to ask whether the unborn human has an objective right to life, just as a human being not located in a uterus has. We also need to consider whether a woman’s right to determine what she does with her body (specifically, whether she uses her body to support another human being) overrides the other human being’s right to life. It’s very difficult to find a thought experiment that mirrors the unique human condition that is pregnancy, but I have found one that seems to come close: that of conjoined twins.
Suppose there is a set of conjoined twins whom we’ll call Aonghus and Barra. If Aonghus and Barra remain conjoined, they have a good life expectancy and quality of life. Suppose also that if they are separated surgically, Aonghus will survive and Barra will die. Does Aonghus have the right to choose to undergo separation surgery without Barra’s consent?
Suppose also that previously the twins could have been separated safely, but that Aonghus took a drug that had a potential side effect of leaving Barra dependent on Aonghus. Suppose Aonghus knew this to be true at the time, but took the drug anyway. Suppose further that the effects of the drug will wear off in eight months’ time, at which point the twins can be safely separated again. Is Aonghus obliged to wait the eight months before getting surgery? Or does Aonghus’s right to bodily autonomy override Barra’s right to not have his life deliberately and knowingly ended, prematurely?
The answer seems obvious – of course Aonghus should not have the right to undergo the surgery. Aonghus does have bodily autonomy, but Aonghus’s right to exercise his bodily autonomy is limited if doing so would directly cause another human being to die. In fact, if these cases of conjoined twins were common, we might even pass laws to prevent such surgeries going ahead. At the very least, any such case that would up in front of a Court would come out in favour of Barra.
The most common response I have had to this argument from pro-choice people, if they answer at all, is that the twins are equal but a woman and a foetus are not. However, in making this point, they have implicitly acknowledged something huge: bodily autonomy is not absolute. The right to not have one’s life deliberately and knowingly ended does override the right to bodily autonomy. This means that if abortion is an ethically acceptable choice, it is not because of bodily autonomy arguments, but because for some reason a foetus is unequal to a woman. Are there any plausible reasons that fall into this category? Great question! But perhaps we should answer it in another blog post.
Muireann
The Minimise Project 
Here is my take.
The twins SHARE the organs in a way that differs from the fetus/unborn child does.
So if the twins are born with one heart, it doesn’t matter that it physically resides in one of the twins, they both have the right to the heart.
Whereas the mother and unbord child/fetus are two different entities that have their own set of organs.
This is why I believe the comparison fails.
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Conjoined twins are two people with one body that they share together. Would undergoing that surgery without the consent of the also other would be a violation of bodily autonomy anyway? The reason why Barra refuses the surgery could be because it could end his life, but first and foremost it involves his body and future.
You are correct that pregnancy is a unique situation because unlike your analogy, the woman and the fetus are not combined.
However, these conjoined twins are both born people with the right to bodily autonomy. The problem is that they both live together with one body instead of two. It’s like they are roommates who both pay for the apartment, and one can’t make a drastic decision without the other’s approval. I could argue that if Barra didn’t consent to the separation, then it would be a more matter of autonomy.
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And like the other commenter said, conjoined twins share one body and all it’s organs.
Unlike the twins, unborn child and the pregnant woman do not. They are two separate entities who have/are developing their own organs. So, in my opinion, the woman doesn’t really need to check with her nonexistent conjoined twin because she doesn’t share her body with anybody.
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