The principle argument of C. S. Lewis’s _The Abolition of Man_ is that, if we remove objective values from society, we will lose our humanity. Lewis begins with an analysis of an English textbook he calls the _Green Book_, which says that statements of objective beauty are impossible. From this, he builds to the existence of objective moral standards, which to appeal to a neutral audience, he refers to as the Tau, rather than the Natural Law.
He also modifies Plato’s theory of the Tripartite Soul. Where Plato says the “head” is the essential part of a person, and Freud says the gut is, Lewis argues that it is the “chest” which makes us human–our passions, and our ability to control them, are what separate human nature from the angels, which are pure intelligence and the animals, which are pure body.
Then making the case for a Natural Law and a Natural Lawgiver, regardless of the particular deity–that’s a topic he covers in _Mere Christianity_
Finally, in the third section, he warns how the efforts of science to “conquer nature” are really the efforts of a few men to conquer other men using nature as the means. He warns how our modern conveniences, which supposedly increase our power, actually increase our servitude. He gives the examples of “the airplane, the wireless and the contraceptive.” Now, as the use of airplanes and wireless radios (or, now, devices in general) are not intrinsically evil, his inclusion of contraceptives, as one feminist critic but admirer of Lewis put it, “sound like a list of Lewis’s pet peeves.”
However, it is interesting that the concerns raised by Lewis (echoing Chesterton) about those particular devices correspond to the early 19th century prophecies attributed to Our Lady of La Salette–prophecies which, though published later and called into doubt by some sources, uncannily predict the 20th Century. She specifically mentions devices that will allow people to travel in the air and communicate over great distances.
On contraception, though, Lewis warns of the effects it would have on children’s psyches to know they are “planned” by their parents. He says that the Western Democracies are more likely to achieve the “abolition of man” than the Nazis or Communists.
At the end of _That Hideous Strength_, often seen as a novelization of the ideas Lewis addresses in _Abolition of Man_, Dr. Ransom tells reformed feminist Jane Studdock to go be with her husband. Jane asks, “Am I no more than an animal in heat?”
Ransom replies, “More, but not less. Go, and have no more dreams: have children instead.”
The Culture of Death has created the very “Men without Chests [that is, consciences]” Lewis warned us of. 20 years ago, my Dad realized that his students didn’t understand Shakespeare because they didn’t understand the idea of transcendent morality. Why would Hamlet hesitate to “off” the guy who killed his dad? To those born in a culture of abortion and violent movies, killing an inconvenient person was no big deal.
In 1992’s _Planned Parenthood v. Casey_, as well as other decisions, Justice Anthony Kennedy argued, as a positive, what Lewis presented as a negative: that the “right to liberty” implies the liberty to decide for oneself what a person is. Kennedy argues that people can and should determine whether they are alive, and if a child is inside that magical barrier of a few inches, the mother can determine whether or not her child is a person. Kennedy has applied this “reasoning” to other culture war cases, including recent decisions in which he has argued for people to define for themselves what “marriage” is.