The recent midterm elections returned a mixed but ominous report on abortion rights. On the one hand, the various personhood amendments, making a fertilized egg equal to a woman, mostly failed; on the other, representatives of the hard-line, forced-birth movement seemed to carry many a day and election. The growth of local legislation to make abortion ever harder to obtain, particularly for poorer women—and particularly for poorer women in the South—continues, with its special dose of sanctimonious cruelty, forcing women to listen to long lectures on the lives they are supposedly carrying and killing, and forcing unwilling doctors to deliver them. Meanwhile, the Supreme Court showed a special tender consideration for the rights and feelings of the “counsellors” who gather outside reproductive clinics in Massachusetts—which they rarely show for other protesters, and would never tolerate outside their own institution—and oddly reinforced the right of religious fanatics to accost total strangers at a moment of maximum vulnerability, in order to make them feel maximally miserable.

In the midst of this, Katha Pollitt, an old friend of this magazine (and of this writer) has written a bracing, unapologetic polemic in favor of abortion rights. “Pro: Reclaiming Abortion Rights” has two major originalities. First is its lack of bowing or scraping for its pro-woman position. Abortion, in Pollitt’s view, must be seen not as a moral compromise requested by poor, weak women—we’re sorry, and we promise we’ll make it rare, but please, forgive us, we’ll still need it in extremis— but as a positive doctrine of women’s control over their own bodies, and of their own lives and destinies. Abortion, she insists, is a right integral to women’s own autonomy, not a privilege to be used as infrequently as possible. The Clintons’ shrewd formula—“Safe, legal, and rare”—may have been born of political necessity, but it misstates the truth. Abortion need not promise to be rare to be secured as safe and legal. One of the greatest moral achievements of human history—the full emancipation of women—should not be seconded to a metaphysical intuition, one with no scientific support or even coherent meaning: that a fertilized egg makes the same moral claims as an entire person. In a memorable moment in the book, Pollitt points out that the use of sonograms of embryos and fetuses to promote the anti-abortion case—with good reason, since any parent can recall their excitement at first seeing them—is intrinsically misleading:

Sonograms distort reality in another, more subtle way: you can only take a picture of the embryo/fetus if you erase the body of the pregnant woman. As with the famous optical illusion of the duck-rabbit, you can’t see them both at the same time: either you see a rabbit or you see a duck. In a sonogram the fetus is the subject, the woman is the background; the case for its personhood is made by turning her into gray-and-white wallpaper.

The second virtue of Pollitt’s book is that—with the help of some arguments from the late Ronald Dworkin, in particular—it takes seriously, and seriously refutes, the metaphysical arguments that claim some ethical seriousness in the view that a fertilized egg is equivalent to a human being. First, Pollitt sees, and insists, that for a “pro-life” argument to make sense it has to make sense; that it follows from a spiritual instinct, or from religious dogma, however deeply held, is not something that rational people have to pretend to respect. It is easy to cite the source of moral ideas in religious vision. Don’t you know that Dr. King was a Christian minister? Didn’t the ideas of the Abolitionists rise from the Northern churches? It’s perfectly true that many good and noble and necessary ideas have come from churches and chapels—as many others have come from temples, universities, Masonic lodges, and presumably one or two from a Satanic cult. But their relevance and plausibility have nothing at all to do with their source; they have to do with the moral and practical sense they make to those who don’t have any special respect for their origins. Dr. King was a Christian minister whose ideas about equality and social justice were crucially affected by his faith; those ideas were just as crucially affected by Gandhi and, for that matter, as J. Edgar Hoover would have pointed out, by the Communists in King’s entourage. His “Dream” speech, though deeply rooted in his faith, appealed not to the authority of religion but to the common language, irresistible to all, or almost all, of justice and moral order and practical benefit. Lincoln may have entered politics with a passionate hatred of slavery, but once he was a politician his arguments were distilled from passion into reason and law, and sometimes even into legalism.

The moral intuition that abortion is in any way like murder is one that can be tested in the only way we can test such things, by looking at the actual evidence and by observing the actual conduct of the people who claim to hold it. Pollitt calmly reviews it all. No person actually imagines that a zygote is a person. If they did, they would actually equate murder and abortion, and their conduct—only the tiniest fringe is willing to advertise comparable penalties for both—shows that they know perfectly well that they aren’t the same. They are really talking about potentials, not persons. And that pseudo-scientific argument—that an embryo is a person because it contains the DNA of a potential person—is true of any human cell, and certainly true of the countless fertilized eggs that, in the natural course of reproduction, are destroyed before they can develop. A fertilized egg or embryo is not some freeze-dried essence of human but a complex set of potentials that need many, many conditions to develop into a human being. It’s true that the stages of that development are difficult to define precisely. This is not a weakness in the case for making these distinctions but, rather, a condition of their existence. The problem with slippery-slope arguments (“Allow abortion in the first trimester, and it will end in infanticide!”) is not that they are inadmissible but that they are always true. All of biological life exists on a slippery slope, where we walk with ice picks called rules and moral decisions. We may allow abortion without restriction in the first and in the third trimester, and still not permit infanticide. The distinctions, as always, are our own.

This does not make them arbitrary. We have always before us the Enlightenment choice between empty authority and rational argument—between divine rules made by an authority we know for certain to be nonexistent and rational ethical argument we know in advance will be ongoing and inconclusive. This uncertainty causes an enormous strain, huge social anxiety—what Karl Popper rightly called the strain of civilization. But that some people can’t bear the strain is no reason for the rest of us not to go on trying to make sane rules. Accepting moral complexity is a sign of moral maturity.