Nineteenth-century science, from Darwin to Freud, offered a series of body blows to ways of thinking about human beings and human lives that had prevailed since the dawn of civilization. Humans, just like adolescents, were deprived of some of the comforting simplicities of childhood and exposed to more complex knowledge about the world. And twentieth-century intellectuals reacted precisely the way that adolescents react when they think they have discovered Mom and Dad are hopelessly out of date. They think that the grown-ups are wrong about everything. In the case of twentieth-century intellectuals, it was as if they thought that if Darwin was right about evolution, then Aquinas is no longer worth reading; that if Freud was right about the unconscious mind, the Nicomachean Ethics had nothing to teach us.
The nice thing about adolescence is that it is temporary, and, when it passes, people discover that their parents were smarter than they thought. I think that may be happening with the advent of the new century, as postmodernist answers to solemn questions about human existence start to wear thin—we’re growing out of adolescence. The kinds of scientific advances in understanding human nature are going to accelerate that process. All of us who deal in social policy will be thinking less like adolescents, entranced with the most titillating new idea, and thinking more like grown-ups.
For more context on this passage read the excellent article "The Europe Syndrome" at the New Criterion.