NATURAL scientists, chastened by such robust objections to the Enlightenment agenda, mostly abandoned the examination of human mental life, yielding to philosophers and poets another century of free play. In fact, the concession proved to be a healthy decision for the profession of science, because it steered researchers away from the pitfalls of metaphysics. Throughout the nineteenth century knowledge in the physical and biological sciences grew at an exponential rate. At the same time, newly risen like upstart duchies and earldoms, the social sciences -- sociology, anthropology, economics, and political theory -- vied for territory in the space created between the hard sciences and the humanities. The great branches of learning emerged in their present form -- natural sciences, social sciences, and the humanities -- out of the unified Enlightenment vision.
The Enlightenment, defiantly secular in orientation while indebted and attentive to theology, had brought the Western mind to the threshold of a new freedom. It waved aside everything, every form of religious and civil authority, every imaginable fear, to give precedence to the ethic of free inquiry. It pictured a universe in which humanity plays the role of perpetual adventurer. For two centuries God seemed to speak in a new voice to humankind.
By the early 1800s, however, the splendid image was fading. Reason fractured, intellectuals lost faith in the leadership of science, and the prospects for a unity of knowledge sharply declined. The spirit of the Enlightenment lived on in political idealism and the hopes of individual thinkers. In the ensuing decades new schools sprang up like shoots from the base of a shattered tree: the utilitarian ethics of Bentham and Mill, the historical materialism of Marx and Engels, the pragmatism of Charles Peirce, William James, and John Dewey. But the core agenda seemed irretrievably abandoned. The grand conception that had riveted thinkers during the previous two centuries lost most of its credibility.
Science traveled on its own way. It continued to double every fifteen years in practitioners, discoveries, and technical journals, as it had since the early 1700s, finally starting to level off only around 1970. Its continuously escalating success began to give credence again to the idea of an ordered, explainable universe. This essential Enlightenment premise gained ground in the disciplines of mathematics, physics, and biology, where it had first been conceived by Bacon and Descartes. Yet the enormous success of reductionism, its key method, worked perversely against any recovery of the Enlightenment program as a whole. Precisely because scientific information was increasing at a geometric pace, most researchers thought little about unification, and even less about philosophy. They thought, What works, works. They were still slower to address the taboo-laden physical basis for the workings of the mind, a concept hailed in the late 1700s as the gateway from biology to the social sciences.
There was another, humbler reason for the lack of interest in the big picture: scientists simply didn't have the requisite intellectual energy. The vast majority of scientists have never been more than journeymen prospectors. That is truer than ever today. They are professionally focused; their education does not open them to the wide contours of the world. They acquire the training they need to travel to the frontier and make discoveries of their own -- and make them as fast as possible, because life at the edge is expensive and chancy. The most productive scientists, installed in million-dollar laboratories, have no time to think about the big picture, and see little profit in it. The rosette of the U.S. National Academy of Sciences, which the 2,100 elected members wear on their lapels as a mark of achievement, contains a center of scientific gold surrounded by the purple of natural philosophy. The eyes of most leading scientists, alas, are fixed on the gold.
We should not be surprised, therefore, to find physicists who do not know what a gene is, and biologists who guess that string theory has something to do with violins. Grants and honors are given in science for discoveries, not for scholarship and wisdom. And so it has ever been. Francis Bacon, using the political skills that lofted him to the Lord Chancellorship, personally importuned the English monarchs for funds to carry forth his great scheme of unifying knowledge. He never got a penny. At the height of his fame Descartes was ceremoniously awarded a stipend by the French court. But the account remained unfunded, helping to drive him to the more generous Swedish court, in the "land of bears between rock and ice," where he soon died of pneumonia.
The same professional atomization afflicts the social sciences and the humanities. The faculties of higher education around the world are a congeries of experts. To be an original scholar is to be a highly specialized world authority in a polyglot Calcutta of similarly focused world authorities. In 1797, when Jefferson took the president's chair at the American Philosophical Society, all American scientists of professional caliber and their colleagues in the humanities could be seated comfortably in the lecture room of Philosophical Hall. Most could discourse reasonably well on the entire world of learning, which was still small enough to be seen whole. Their successors today, including 450,000 holders of the doctorate in science and engineering alone, would overcrowd Philadelphia. Professional scholars in general have little choice but to dice up research expertise and research agendas among themselves. To be a successful scholar means spending a career on membrane biophysics, the Romantic poets, early American history, or some other such constricted area of formal study.
Fragmentation of expertise was furthered in the twentieth century by modernism in the arts, including architecture. The work of the masters -- Braque, Picasso, Stravinsky, Eliot, Joyce, Martha Graham, Gropius, Frank Lloyd Wright, and their peers -- was so novel and discursive as to thwart generic classification, except perhaps for this: The modernists tried to achieve the new and provocative at any cost. They identified the constraining bonds of tradition and self-consciously broke them. Many rejected realism of expression in order to explore the unconscious. Freud, as much a literary stylist as a scientist, inspired them and can justifiably be included in their ranks. Psychoanalysis was a force that shifted the attention of modernist intellectuals and artists from the social and political to the private and psychological. Subjecting every topic within their domain to the "ruthless centrifuge of change," in the American historian Carl Schorske's phrase, they meant proudly to assert the independence of twentieth-century high culture from the past. They were not nihilists; rather, they sought to create a new level of order and meaning. They were complete experimentalists who wished to participate in a century of radical technological and political change and to fashion part of it entirely on their own terms.
Thus the free flight bequeathed by the Enlightenment, which disengaged the humanities during the Romantic era, had by the middle of the twentieth century all but erased hope for the unification of knowledge with the aid of science. The two cultures described by C. P. Snow in his 1959 Rede Lecture, the literary and the scientific, were no longer on speaking terms.