Purely for the sake of clarifying an earlier post, in which I objected to a rather vehement critique of a neoconservative's commentary on abortion, I would like to offer an observation about two rival visions of ethical and political thought, at least as they implicate the abortion question.
There is a tendency or school of thought, with which I have a fair measure of sympathy, according to which highly abstract, deontological ethical systems are not merely methodologically flawed, proceeding as they do (or are thought to do) from the assumption that ethical thought is a deductive science, a spinning out from a few axioms articulated moral schemes (thus, in a sense, that they are ideological and reductive, in the invidious sense familiar to most intelligent conservatives), but that such systems yield undesirable and false consequences when applied to to concrete human relations, in all of their complexity and nuance. Obviously, a moment's reflection will show that these two criticisms are related in practice, but in polemical uses, one often observes shifts between them suggestive of indecision, as though a writer cannot quite decide what he finds most objectionable - his opponents methodology, or his conclusions. It is not always clear that the answer to this question is, "both", and we are all doubtless familiar with instances of polemic in which a position is rejected, ultimately, because someone simply disapproves of the use made of it. The methodology is rejected, not so much for its own sake, as because someone has gone and done something daft with it.
That said, there is a rough distinction to be drawn between a sort of abstract, deontological, rights-based ethical theory and an old-fashioned, natural law/casuistry approach in which the natural law is explicated by means of painstaking attention to the concrete relations and circumstances in which ethical questions arise. Anyone who has read The Morality of Everyday Life, or is conversant with some of the debates between various natural law traditions will know what I'm talking about. However, it seems to me that this debate has absolutely nothing to do with the abortion question, except to the extent that the discourse of rights, tainted as it is by voluntarism and various modern mythologies of will and consent, carries associations and atmospherics adverse to the intentions of abortion opponents. It is a category error to introduce this methodological question - with the exception of the caveat already given - into the discussion of abortion and the ontological/moral status of the unborn child. This dispute would be relevant to the question of abortion if and only if the normative outputs of the different approaches would differ: In other words, if and only if, in the case of a more casuistic approach, there exists a possible relational state or set of circumstances such that, where and when it obtains, abortion becomes licit. However, on an old-school natural law approach, there is no such relational state or set of circumstances, no contingency which negates or trumps the ontological relation of parent and child, no defeater for that primal obligation, and thus, no real possibility that abortion becomes licit. There exist differences of terminology - some of which are convertible, but leave that aside - but no real differences in the underlying intuitions and moral norms, at least in the case of abortion.
The only reasons I can perceive for confusion on this point are a misunderstanding of the different approaches and how they arrive at their conclusions w/r/t abortion, sheer animus against a commentator, and a rejection of the categorical nature of a prohibition. In the case at hand, given the evidence, we can definitively exclude options one and three.