Clearly, collecting bone marrow from somebody by force is and active action, and to justify this, one would have to say that the active right of the person needing the bone marrow trumps your passive right to bodily autonomy.

For an abortion, you turn this on its head. If no action is performed, the fetus will most likely surivive in the womb until it's born.

Now, you may claim that fetus is somehow commiting a crime by extracting resources from the mother's body. The problem with this argument, is that this crime is first of all not voluntary. The fetus doesn't have a way to stop doing so by an act of will. Second, the fetus is not developed enough that we would assign moral agency to it (just like we would not do that to a baby after birth).

Now, if you believe (like me, especially in the first trimester) that the fetus is not a person, and doesn't have the legal rights of a person, it is still probably ok to abort it.

But if you think that the fetus IS a person, it also follows that it deserves the same protections as a person. In other words, the passive right of the fetus to not be "murdered" is in conflict with the passive right of the mother to not have its resources extracted. The fact that the passive right to not be murdered may be considered a stronger right than the mothers right to bodily autonomy.

Also, in this situation, there are two more factors to take into account:

1) This conflict between the two subjects involved was not caused by any actions of the fetus. Unless she was raped, though, the mother most likely played a part in the conception of the fetus, so bears some responsibility for being in such a situation.

2) Even though there is a real conflict of interests, the MOST passive approach is to not abort, while aborting requires active intervention.

So, I would argue, IF the baby is to be considered 100% a person, with exactly the same protections by the law as the mother, it is logical that abortion is banned.

Now, personally, I don't agree with this premise. In fact, I see the fetus as becoming a person gradually, and I'm not even sure if it reaches fully 100% at birth (though close enough for practial purposes, at least as long as the mother is not starving). Personally, I think the fetus at conception should have 0 person-rights. After 2-3 months, maybe similar to a farm animal, and during the 2nd trimester, probably similiar to your favourite pet.

Only during the 3rd trimester, once the baby would be able to survive outside the womb, would I consider it to get close to deserve the same protectino as a baby after birth.

> I wasn't clear then: I don't care in the context of this question. We already don't require you to donate bone marrow to save a specific person.

And with all due respect, I think perhaps what you're really saying is not that you disagree with the reasoning above, but rather that you refuse to seriously consider the premise of the Christian fundamentalists. In other words, I think you refuse to really imagine that you see the fetus as a 100% full person.

Now, I'm not meaning to imply malice on your part. To understand another person's perspective when they disagree with you about something fundamental is hard It requires a lot of empathy to do so, and it is not easy to find this kind of empathy for a perspective or group of people that one has negative emotions for.

I am sidestepping this issue by replacing the fetus with something that is 100% human, so it doesn't matter if the foetus is or not.

As for it being an active action or not: if we instead were to leave the foetus in place, but remove all the connection to the uterus only, it would still die due to lack of nutrients.

You are right that the woman might have been involved with an activity that can cause babies, but then you can get into the weird arguments about liability to third-parties that do not exist at the time of the action, and the feotus in the end is no different (it does not live) as it would have if the woman had choosen to use other means, such as condoms or not had sex at all.