Well, I can’t speak for all pro-choice folks, but for me, here goes:
I don’t personally buy into the idea that fetuses aren’t human, or that they aren’t sentient, or that they’re just tissue. For me, I don’t think that I would personally be able to have an abortion (I would say absolutely not, but it’s easier to say you’ll do a thing than to actually do it). My pro-choice views apply to society, not to me personally. As we all know, idealism doesn’t always work in society. As an ideal, it would be nice if there simply wasn’t a need for abortion. Unfortunately, there is, and I simply find that supporting outlawing abortion would be more unethical than supporting it for a number of reasons:
Outlawing abortion would not eliminate it: Like prohibition and the war on drugs, outlawing something for which there is great demand does not make it go away. I would much rather that if a person believes an abortion is their best choice that they go to a clinic to do so rather than potentially injuring or killing themselves by attempting to do it alone or through some underground quack.
My ethics aren’t global: I don’t feel I have the right to apply my ethics to everyone. There is sufficient debate on the abortion issue to lend credence to the fact that people have very different views of it. In so long as there is such a moral divide, I feel very uncomfortable trying to push my sense of what is right and wrong on other people through law.
Resources are limited: I believe overpopulation is a serious issue. Social programs are already taxed, and those who are supporting an abortion ban are also supporting decreasing social programs.
Most importantly, there is no way for the fetus to have human rights while still maintaining the human rights of the mother. You can talk about people in comas all you like, but the fact of the matter is that pregnancy is unique in that two human persons are intertwined in a parasitic relationship (I do not mean this negatively, simply in the true sense of the word) and that there is no way to give the fetus human rights without challenging the mother’s. As pro-choicers often say, “my body, my choice”. Not being able to control your own body is a violation of our most basic right as humans. Pregnancy is a big deal – sometimes lifethreatening, and certainly often threatening to livelihood, career, etc. I can’t make pregnant women prisoners – think of all the things a pregnant woman can’t do. And should we stop there? After all, pregnant women don’t always know right away – should potentially pregnant women also not be able to drink, smoke, go horseback riding, or whatever? What should happen to women who do, if anything (after all, couldn’t inducing miscarriage be considered murder, or manslaughter, if fetuses are fully persons? Will miscarriages be investigated? Will pregnant women be monitored?).
Simply put, pro-life individuals have not answered all of these concerns. Practically speaking, it is simply not a good idea to outlaw abortion – abortion, it seems, beats the alternative.