Exactly! The concept of an abortion as a whole is not what even pro-lifers reject, else they would have to condemn miscarriages as well. It is specifically that they oppose human intervention in the matter.
Let me, for the sake of what I find to be an interesting train of thought, propose an overly loose definition of a disease. One might define a disease as a biological state that is not the norm and which the individual does not desire.
Naturally, a person's body will attempt to fight off the disease and return the body to homeostasis.
Unnaturally, medicine might attempt to mimic the natural occurrence and fight off the disease with external means.
If this disease is, say, cancer, the natural responses tend to be incredibly inefficient and so unnatural responses are needed.
But under this overly loose definition of a disease we might also classify an unwanted pregnancy as a disease. Being pregnant is not the normal biological state of most women in the modern era, and in some cases it is undesired. Like with cancer, the natural mechanisms to fight off disease are not here effective and thus we might suppose that unnatural means are necessary.
Assuming that this very strange definition of a disease was accepted by you, would one still have an objection to unnatural medical intervention that attempts to do what the natural functions would ideally be doing?
Of course the objection still might be that, though perceived as a disease, the woman to a degree chose to engage in behavior that, even with proper precautions, still has a much higher risk of causing pregnancy than most behaviors have of causing cancer. Action and intent thus remove our medical obligation of treating the "disease."
And so allow me to switch the disease from a fetus or cancer to that of an STD. Like the others, it is not a normal biological state for an individual and it is (usually) undesirable. But one contracts an STD like one "contracts" a pregnancy. We find many of the same behaviors, and failures of many of the same precautions, lead to this state. The natural functions of the body are not always (indeed, not usually) able to fight of these diseases and so we find unnatural medical intervention to be called for.
I object to bans on abortion just as I would object to bans on treatment for STDs. While I might not approve of the behavior that leads to the desire for medical intervention, I cannot in good consciousness withhold medical help after the fact. I cannot claim that a man suffering from STDs should be denied an unnatural medical solution to his problem merely because he engaged in behavior that specifically caused his affliction in the first place. Neither can I claim that a woman suffering from pregnancy be denied an unnatural medical solution to her problem merely because she engaged in behavior that specifically caused her affliction in the first place. To withhold help seems downright un-Christian, as it were.
And since for humors sake I have here introduced an aspect of religion, allow me a few sentences more on this topic before once more putting it aside. The Christian might object to abortion based on the perspective that it is wrong. Likewise a Christian might object to robbery based on the perspective that it is wrong, and yet Christian teachings include the belief that if someone takes something from you by force that you should follow it up by giving them something more willingly. Thus it would seem from a Christian’s perspective, even though the Christian might believe that abortion is wrong, it is the moral obligation of the Christian to aid those engaged in abortion. But now enough of that.
Setting aside this absurd definition of a disease, one will most likely balk at the supposition that a pregnancy can be considered a disease. A fetus is human, or at least comprised of human genetic information, an STD is not! Ah, but cancer is comprised of human genetic information as well. A fetus has a heart! Ah, but cancers may well have heart cells in them, and these cells might even be "beating." A fetus, if left not externally treated like a disease, will develop into a child! Not necessarily, the internal processes of the body might well address the issue. The woman engaged in behavior that made her pregnant! As did the man with the STDs.
This is not to say that abortion is "good" and that it would be in an ideal society. Far from it, abortion would not be in an ideal society simply for want of a need or desire for it. However, we are not in an ideal society and so having it as an option is better than not having it at all.
What I find ironic is that this wholly worldly definition of human life is not only embraced by religion, but it is fought for tooth and nail, shouted on street corners, and otherwise... revered. I'm not trying to bring religion to far into this, but I do find that to be more than a tad contradictory with what most religions otherwise hold, or at least should hold, in high regard given their choices of teachers.
You've touched on the concept of ensoulment. When does this guise of biological matter become endowed with that which is eternal? If we are dualists and say that the body is merely a device and we are the controllers in it, then the mind becomes a tantalizing place to define as the cockpit. If the cockpit is functioning, then the soul might well be there. If we are not dualists, we might well claim that the soul develops alongside the physical form. Or we might say that it occurs at birth, other at some other largely arbitrary date.
... for something which does not yet share that capacity to dream in the slightest?
An unimportant curiosity, as this wasn't the sort of dreaming you were referencing, but does anyone know when REM sleep begins?
For me, I find it not only sad but dangerously misleading to want to call outright "human life" that which is so utterly lacking in the capacity to live as a human.
The problem there is that there is little difference between a child that is a day old and a child that is a month till due. Indeed, there is even less difference between a child born a month premature and a child that is two months till due. If a child is outside of the mother and still alive, as a society we say that it is wrong to kill it. So it would seem that there is a line somewhere that on one side of which there is not a human and on the other side there is. Where that line is is difficult to determine. That is one of the very interesting things about the A Defense of Abortion essay Faust was talking about earlier; it takes it as a premise that a fetus is human and has a right to life but then goes on to argue what that doesn't preclude the possibility of an abortion.