From the first moments that the issue of abortion began to arise as one of the central, contentious parts of our national politics, it was as plain to the pro-lifers, as it was preposterous and offensive to the pro-choicers, that the issue of abortion and the issue of slavery shared the same root in principle. Every mode of argument for the “right to abortion” found its analogy in the arguments used to justify the right of some humans to hold others as slaves. Abraham Lincoln crystallized the matter, in a moment of high clarity, when he remarked that Stephen Douglas’s policy of “popular sovereignty” reduced finally to this: “the right of one man to make a slave of another without any right in that other, or anyone else, to object.” In our own time the philosopher Russell Hittinger would draw the parallel to abortion: that one person may kill another and a third may not object—for it is a matter now of “privacy.” But of course there could be no right of privacy to take the life of another human being for wholly private reasons, short of preserving one’s own life from a deliberate assault (a design that could never be imputed to a child in the womb). The matter had to turn on whether the life that was extinguished was really a “human” life. Cutting to the root of things, as usual, Lincoln argued that the question about slavery was whether a negro is not or is a man. If he is not a man, why in that case, he who is a man may, as a matter of self-government, do just as he pleases with him. But if the negro is a man,…then my ancient faith teaches me that “all men are created equal;” and that there can be no moral right in connection with one man’s making a slave of another.
The surprise is that the comparison of slavery and abortion should ever have occasioned surprise. For at the core of both matters was that question of what John Paul II would call “the human person.” In our own age, and in Lincoln’s as well, we were already distant from Aristotle’s biology. No educated person could have held that the offspring in the human womb went through an “animal” stage before it advanced to the condition of a “rational” human conceptus, embryo, fetus, child. There was no change in substance anywhere along the chain of development as the same creature powered and integrated its own development. –from “Twin Barbarisms” (2014)