Minute Particulars has a post, whcih he admits at the outset might be half-baked, on the differences in motivation between those who favor and those who oppose legal abortion. The gist of it is that pro-choicers are motivated by self-interest -- I or someone like me might want to have an abortion -- while pro-lifers are only concerned for others, because no one's in danger of becoming a fetus.
That premise is half-baked, in my opinion. I actually blogged about this a while ago when Charles Murtaugh argued from the similarly half-baked premise that abortion is in the interest of all women and against the interest of all men. My post wasn't exactly baked to crispy brownness itself, but I brought up a study of pro-life and pro-choice women that I'd read about in college. Essentially, there was a disagreement between them about what makes women valuable. The pro-life women were heavily working-class, and found meaning and power in motherhood that they did not find in the workplace. The pro-choice women were the reverse: more affluent, more likely to see children as getting in the way of a career.
Now, you could say, that's all very well for women who choose not to have abortions themselves, but where the self-interest in trying to stop others from having them? The strong feeling I got from that study, as well as a lot of other pro-life rhetoric, was that the presence of abortion on demand leads to a cultural devaluation of motherhood, and a shift in expectations of what women are supposed to be like.
Connected to this fear is the fear of male irresponsiblity. In another past post I half-jokingly proposed a quick-and-dirty test to predict a woman's view of abortion: are you more afraid of a man controlling you, or running out on you? Pro-choice rhetoric is full of scare language about "controlling women's bodies," while pro-life language often expresses the fear of men screwing around without consequences. Just today Jane Galt wrote:
More troubling, the feminist movement has not merely tried to render the legal ability to choose that men have always had (and pro-life readers should remember that while the choice of men to abandon their children is not quite as final, it is nonetheless horribly detrimental). Rather, it has sought to make the choice to abandon a child created through consensual sexual activity not merely legal, but also an acceptable, even laudable, moral choice. In doing so they have also legitimated the decision of men to abandon their children, which makes them sound a bit thick when they complain about gents who have decided to retroactively excercise some reproductive choice by failing to pay their child support.
She's not the only one to feel that abortion has women importing some of the worst traits of men. Eve Tushnet characterized this as "making women equal by making us men--adapting women to a man-made world rather than adapting that world to women."
It's also worth noting, in a First Things article a couple months ago, how quickly Federica Mathewes-Green slid from talking about cultural attitudes toward abortion to talking about cultural attitudes toward sex in general. For many -- probably most -- pro-lifers, legal abortion is tied up in a complex of sexual mores that they find deeply threatening.
None of this says, necessarily, that there isn't an altruistic reason to oppose abortion. Just that I don't think you can reduce it to the simple binary that Mark does. I think that pro-choicers know this, and so if you try to persuade them you're in the cause purely out of the goodness of your heart, they're not going to believe you.