When Sciences Converge

__"History and the Scientific Worldview" by William H. McNeill, in History and Theory (Feb. 1998), Blackwell Publishers, 350 Main St., Malden, Mass. 02148.__

Craving universal and unchanging truth, historians and social scientists have long looked wistfully at the natural sciences, with their imposingly objective, quantitative character. But the revolutionary transformation of physics and cosmology over the last half-century has made the natural and social sciences much more alike, contends historian McNeill, author of The Rise of the West (1963).

At the beginning of the century, physics and astronomy, being exact, cumulative, and predictive, were the ideal toward which not only social scientists but even scientists in other fields, such as biology and geology, aspired. But then, in the 1920s, the old, Newtonian certainties began "to crumble with the emergence of quantum mechanics," McNeill notes. Three decades later, "the universe as a whole became openended and unstable ...when a coalition of cosmologists and small-particle physicists began to compose a new and very surprising story of how it all got started and proceeded to evolve across the past 10 to 15 billion years." Instead of the predictable cosmos, obeying universal mathematical laws, that scientists between the 17th and 19th centuries had seen, there was now an expanding universe that had begun with a Big Bang and in which "the ultimate limits of our familiar matter, energy, space, and time are sporadically approached, or perhaps even crossed, in the neighborhood of Black Holes, quasars, and the like."

This very different cosmos, McNeill observes, "begins to resemble the chaotic and changeable world that biologists and social scientists have always struggled to understand." In their effort to obtain eternal, objective truths, historians and social scientists have always been hampered by "the role of the observer in creating what is observed." Now, physicists are haunted by the same dilemma. "Einstein’s relativity and the oddities of quantum mechanics both drew attention to the inescapable involvement of the act of measurement with what is measured," McNeill notes.

Cosmologists, he continues, now debate whether the universe of their surmise may be forced "to conform to what human minds and humanly created instruments are capable of observing. The resulting epistemological dilemma is acute, even though practicing scientists usually prefer to disregard it. But the notion, propagated in the 17th century, that physical science, relying on the certainties of mathematics, could achieve accurate predictability and an unambiguous description of external reality is no longer very plausible."

At every level of intellectual organization—whether physical, chemical, or biological, or at the level of humanly invented verbal and mathematical symbols—complexity is giving rise to new and surprising sorts of behavior, McNeill points out. The natural and social sciences, he concludes, have begun to converge around a "grand evolutionary worldview." He predicts that this congruence of the sciences will prove to be "the primary intellectual achievement of the 20th century."