Consent must be freely given and ongoing.

This argument proves too much. Does the right to stop consenting never end? Can a woman morally say to a doctor “I don’t like that small little thingy in the crotch of the ultrasound. Let’s kill it”? Can she decide around month eight that this whole child-rearing thing isn’t for her after all? How about the little bugger invading her personal space after it is born? Can she morally refuse to have anything to do with her child, because the libertarian “consent” claim applies to more than invasion of our bodies? (Comedian Alan King had a great line about being a grandfather: “I tried to child-proof the house, but the little bastards got in anyway!”)

Hierarchy of life is not the point. The final episode of Seinfeld notwithstanding, the duty to rescue is different from the duty not to kill. We cannot live under a rule that requires us to rescue strangers. Natural selection won’t allow it. But we can live under a rule that forbids us to kill strangers. So, if we temporarily disallow the special exemption of our own offspring from our autonomous whims, abortion and keeping one’s kidneys remain very different moral issues.

Nor does the false dichotomy of action vs. inaction come into play here. (So, yes, you are straw-manning this one.) The issue is the specific duty to provide help or not provide help, to be self-interested or altruistic, with respect to a specific category of choice. One cannot generalize about this, because the question is really whether this particular case is an exception to whatever general rule you would otherwise rely upon. Just stating the general rule gets us nowhere.

The reason we have no general obligation to rescue is not that failing to rescue is “inaction.” Lifeguards are morally responsible for not guarding lives. The lifeguard cannot, while on duty, morally decide to withdraw consent to the obligation undertaken. Why can we not impose as a moral rule the idea that voluntary unprotected sex is no different from “going on duty” for the next eighteen years and nine months? Police are morally obliged to save strangers. Why aren’t mothers morally obliged to save their babies?

I am pro-choice because, as a legal matter, I do not want the law intruding into this particular area of people’s lives. It’s a matter of “encapsulation” of the risk: a person who kills strangers is a danger to the community; a person who kills her own unborn fetus in the first tri-mester, not so much. But I am pretty well satisfied that abortions of convenience are immoral. If you can’t nurse the seed, don’t do the deed. I find all the arguments for the moral ok-ness of “ordinary” abortions unpersuasive, and I find all the practical arguments for the legal suppression of abortion unworkable. Law and morality are not congruent. They overlap in some areas, but they complement in others. Abortion, I believe, falls into the latter category: a moral offense that should not be made illegal.