Of all the arguments advanced against the legalization of abortion, the one that always struck me as the most questionable is the most consequential: that the widespread acceptance of abortion would lead to a profound moral shift in our culture, a great devaluing of human life. This seemed to me dubious on general principle: Projections of this sort almost always turn out to be wrong because they fail to grasp that, in matters of human behavior, there is not really any such thing as a trendline. People change to meet new realities and thereby change reality.

Thus, for the environmental hysterics of the 1970s, the nuclear freezers of the 1980s and the Perovian budget doomsayers of the 1990s, the end that was nigh never came. So, with abortion, why should a tolerance for ending human life under one, very limited, set of conditions necessarily lead to an acceptance of ending human life under other, broader terms?

This time, it seems, the pessimists were right. On Sunday, Nov. 2, an article in the New York Times, the closest thing we have to the voice of the intellectual establishment, came out for killing babies. I am afraid that I am sensationalizing only slightly. The article by Steven Pinker in the Times' Magazine did not go quite so far as to openly recommend the murder of infants, and printing the article did not constitute the Times' endorsement of the idea. But close enough, close enough.

What Pinker, a professor of psychology at the Massachusetts Institute of Technology, wrote and what the Times treated as a legitimate argument, was a thoroughly sympathetic treatment of this modest proposal: Mothers who kill their newborn infants should not be judged as harshly as people who take human life in its later stages because newborn infants are not persons in the full sense of the word, and therefore do not enjoy a right to life. Who says that life begins at birth?

"To a biologist, birth is as arbitrary a milestone as any other," Pinker breezily writes. "No, the right to life must come, the moral philosophers say, from morally significant traits that we humans happen to possess. One such trait is having a unique sequence of experiences that defines us as individuals and connects us to other people. Other traits include an ability to reflect upon ourselves as a continuous locus of consciousness, to form and savor plans for the future, to dread death and to express the choice not to die. And there's the rub: our immature neonates don't possess these traits any more than mice do."

Pinker notes that "several moral philosophers have concluded that neonates are not persons, and thus neonaticide should not be classified as murder," and he suggests his acceptance of this view, arguing that "the facts don't make it easy" to legitimately outlaw the killing of infants.

Pinker's casually authoritative mention of "the facts" is important. Because Pinker is no mere ranter from the crackpot fringe but a scientist. He is, in fact, a respected explicator of the entirely mainstream and currently hot theory of evolutionary psychology, and the author of "How the Mind Works," a just-published, doubtlessly seminal, exceedingly fat book on the subject.

How the mind works, says Pinker, is that people are more less hard-wired to behave as they do by the cumulative effects of the human experience. First cousins to the old Marxist economic determinists, the evolutionary psychologists are behavioral determinists. They believe in a sort of Popeye's theory of human behavior: I do what I do because I yam what I yam because I wuz what I wuz.

This view is radical; it seeks to supplant both traditional Judeo-Christian morality and liberal humanism with a new "scientific" philosophy that denies the idea that all humans are possessed of a quality that sets them apart from the lower species, and that this quality gives humans the capacity and responsibility to choose freely between right and wrong. And it is monstrous. And, judging from the writings of Pinker and his fellow determinists on the subject of infanticide, it may be the most thoroughly dishonest construct anyone has ever attempted to pass off as science.

Pinker's argument was a euphemized one. The more blunt argument is made by Michael Tooley, a philosophy professor at the University of Colorado, whom Pinker quotes. In his 1972 essay "Abortion and Infanticide," Tooley makes what he calls "an extremely plausible answer" to the question: "What makes it morally permissible to destroy a baby, but wrong to kill an adult?" Simple enough: Personhood does not begin at birth. Rather, "an organism possesses a serious right to life only if it possesses the concept of a self as a continuing subject of experiences and other mental states, and believes that it is itself such a continuing entity."

Some would permit the killing of infants "up to the time an organism learned how to use certain expressions," but Tooley finds this cumbersome and would simply establish "some period of time, such as a week after birth, as the interval during which infanticide will be permitted."

And Tooley does not bother with Pinker's pretense that what is under discussion here is only a rare act of desperation, the killing of an unwanted child by a frightened, troubled mother. No, no, no. If it is moral to kill a baby for one, it is moral for all. Indeed, the systematic, professionalized use of infanticide would be a great benefit to humanity. "Most people would prefer to raise children who do not suffer from gross deformities or from severe physical, emotional, or intellectual handicaps," writes eugenicist Tooley. "If it could be shown that there is no moral objection to infanticide the happiness of society could be significantly and justifiably increased."

To defend such an unnatural idea, the determinists argue that infanticide is in fact natural: In Pinker's words, "it has been practiced and accepted in most cultures throughout history." This surprising claim is critical to the argument that the act of a mother killing a child is a programmed response to signals that the child might not fare well in life (because of poverty, illegitimacy or other factors). And it is a lie.

In fact, although millions of mothers give birth every year under the sort of adverse conditions that Pinker says trigger the "natural" urge to kill the baby, infanticide is extremely rare in all modern societies, and is universally treated as a greatly aberrant act, the very definition of a moral horror. The only cultures that Pinker can point to in which infanticide is widely "practiced and accepted" are those that are outside the mores of Western civilization: ancient cultures and the remnants of ancient cultures today, tribal hunter-gatherer societies.

And so goes the entire argument, a great chain of dishonesty, palpable untruth piled upon palpable untruth. "A new mother," asserts Pinker, "will first coolly assess the infant and her situation and only in the next few days begin to see it as a unique and wonderful individual." Yes, that was my wife all over: cool as a cucumber as she assessed whether to keep her first-born child or toss him out the window. As George Orwell said once of another vast lie, "You have to be an intellectual to believe such nonsense. No ordinary man could be such a fool." Michael Kelly is a senior writer at National Journal.