To the question whether abortion is connected, via the sexual revolution, to the liberalization of sexual mores, Nick’s answer of “yes and no” is correct. But I would be more specific about the “yes” and the “no.”
Are all these issues joined by a common sociocultural cause, the abandonment of the idea that “sex is teleological”? Just yes.
There is something in that “yes and no” for both “traditionalists” and “revisionists.” Returning to a pre-Sixties sexual ethic would, no doubt, reverse a wide range of ills by cutting them off at an early link in the causal chain. On the other hand, it ought to be possible to adduce specific reasons to think that the various ills are, in fact, ills. If so, the public, given time and presented with an adequate persuasive effort, can reasonably be expected to embrace an updated set of mores that takes all of these reasons into account. Of course, if you think the older mores are correct on their own terms, you think there’s no need for an update; and if you think they aren’t, you cannot call other than cynically for a return to them.
There has been a lively discussion going on about whether the natural law can be directly observed in nature as nature presents itself to us, or, alternatively, is expressed through practical reasoning and human decision-making. I don’t speak for either camp, but I think the question has interesting implications for the present debate. Someone who takes the first approach will note the objective biological function of sex and derive ethical conclusions from this function. Someone who takes the second will proceed from the subjectivity of a rational agent and ask what goods such an agent seeks.
The landscape of human knowledge, choice, and action is not fixed, and its development can accordingly bring about development in our ethical understanding. In any such process, interpretive generosity and a willingness to pursue disagreements to their most fundamental level are extremely important. Absence of either, but especially of the latter, will compromise the quality of discussion. You might claim, for example, that so-and-so is a relativist when he really just has substantively different judgments from yours. More concretely, you might claim that people who use contraception want to have sex just for fun, or to gain some private good such as a sensation or an emotion, when by their own lights they seek a kind of interpersonal communion not reducible to the foregoing goods. A proper understanding of what they seek might lead to a broader understanding of teleology. (For a forceful and delightfully opinionated treatment of the radical difference between subject-object relations and interpersonal relations, see A Brief Inquiry into the Meaning of Sin and Faith, the work of a 21-year-old John Rawls.)
The development of our ethical understanding can in turn trigger development in the social institutions that we construct in its light. Here it is important to bear in mind the twofold nature of such a process: Of course social institutions have no reality independent of their social construction; but of course we do not construct them willy-nilly, but rather in response to what we perceive of the reality of the human condition. Failure to recognize this hybridity can lead to a lot of fruitless and repetitious debate between “realists” and “constructivists.”
I thank Nick for his whole post, and especially for his anecdote about “Nino” and “Ruth.” That is the proper spirit in which to conduct any discussion of a contentious issue. It is preferable in every way to calls for excommunication and personal attacks.