Thomas S. Kuhn (1922-1996) is recognized as one of the foremost historians of science to have emerged in the 20th century. He is credited with a controversial approach to understanding scientific development, one that emphasizes rare but significant revolutions that challenge and even overthrow traditional ways of observing the world. Such revolutions, he claimed, change our views so profoundly that it may be unreasonable to compare theories that originated in different times. It is unfair, for example, to judge the writings of Aristotle (384-322 BCE) according to the standards of proof required today, not only because Aristotle could not have been aware of the scientific discoveries since his time, but also because the ancient Greeks understood worldly phenomena according to a different set of guiding principles. The scientific revolutions of more than 2000 years have rendered our perspectives beyond comparison; Kuhn calls this the “incommensurability thesis.”
Kuhn studied physics at Harvard before teaching the philosophy of science at a variety of schools (most recently Princeton and MIT). His book The Structure of Scientific Revolutions (1962) inspired intense controversy by calling attention to the limitations of accepted scientific methodology. Kuhn wrote that science, or rather scientists, proceed through time operating according to a collection of accepted theories. There are few challenges to these theories, because they are assumed to reveal truths about the world. Because the scientific method has already exhaustively tested such explanations, any new work by scientists is expected to conform to accepted laws and principles. Occasionally, however, the conventional knowledge base is unable to answer a particular problem, or worse, it is at odds with a new theory or observation. When a solution emerges that resolves such a crisis by overthrowing previously accepted elements of scientific knowledge, then what Kuhn calls a revolution has occurred.
The term paradigm shift originated with Kuhn’s vision of a scientific revolution that interrupts the normal thought paradigm. The traditional view of science presumes continual progress as advancements contribute to an ever-growing base of knowledge. When theories are revised and formerly held principles abandoned, then science simply has witnessed a correction that brings us closer to an underlying truth. Kuhn rejected this traditional view. Instead, he claimed that there are long periods with negligible progress, what he called normal science (operating within conventional knowledge) that are occasionally punctuated by revolutions. There is monumental progress in science, Kuhn would claim, but only through the process of alternating eras: convention, revolution, convention, revolution, etc.
Scientists might pursue monumental innovations (e.g., inventions, discoveries, cures for diseases), but they are held back, Kuhn claimed, by the prevailing wisdom of the time. In other words, the tendency is to think inside the box. This urge for innovation, restrained by conventional thinking, Kuhn referred to as the essential tension. In his view, revolutions are not actively sought. Instead, changes in thinking occur as a matter of necessity when accepted principles are replaced by the new paradigm. Advancement has less to do with individual accomplishments than with new modes of thinking that are so profound that they render obsolete some aspect of the former status quo. If science consists of games or puzzles, then there are familiar rules under which we attempt to solve problems. A true paradigm shift introduces not just a new puzzle to be solved, but new directions for answering old questions. The new theory not only resolves some inadequacies of past thinking, but also launches a new set of problems and guidelines for proceeding. Kuhn was not suggesting that individuals strive to overthrow established consensus. Rather, he was describing a cycle of convention, crisis, revolution, and new convention.
To Kuhn, this theory was not just for the history and evolution of frameworks in science; science itself is evolutionary. When science meets with the hostile environment of an unsolvable problem, adjustments are made to address the challenge. In the traditional view of science, competing theories battle against one another; through the trial and error of the scientific method, the strongest theory emerges victorious and progress is claimed. For Kuhn, however, the competition pits the existing body of scientific knowledge against conflicting ideas; challenges to the standard way of thinking are discredited by conventional scientists, because their operating principles are regarded as truths. If a sufficient number of scientists present the same new idea over time, or especially if a new idea successfully resolves a major problem that has plagued science for a very long time, then that new idea might be paradigm shifting.
In embracing the revolution, the evolutionary change is dramatic. Where traditional science would (reluctantly) accept new information as an addition to the growing body of knowledge, however, Kuhn emphasized that some old theories, instead, are discarded to make way for the new. In organic evolution, fins are replaced with limbs, not augmented by them; it is absurd to imagine a creature that collects and maintains every feature its ancestors have ever possessed (the platypus notwithstanding). To continue the analogy, Kuhn saw revolutionary science as changing significantly enough that appendages are no longer recognizable. Traditional science, like Darwin’s original conception of evolution, envisioned a series of continual changes over time. To recognize biological evolution as a series of periodic responses to catastrophes, however, is more akin to Kuhn’s vision: Scientific revolutions are reactions to intellectual crisis, but they are rare.
The conventional view of science, according to Kuhn, is mistakenly teleological; it presumes that scientific inquiry is progressing toward a particular goal. The principles originally developed through the observation of patterns in nature have been elevated to such esteem that they are taken as truths about the world or, in any case, as steps toward eventually knowing an objective and unchanging Truth. Just as evolutionary adjustments might be arbitrary, though, responding as they do to challenges posed by the external environment, in Kuhn’s view scientific advancement is vulnerable to sociological influence. History has shown that political bias sometimes keeps science at bay: Followers of Copernicus were convicted of heresy for daring to support his theory of heliocentrism (e.g., Giordano Bruno was burned at the stake; Galileo Galilei was placed under house arrest). Indian astronomers as early as the 7th century BCE (and ancient Greeks 300 years later) had believed the earth to rotate around the sun, yet religious influence prevented acceptance for centuries. Like the Connecticut Yankee, regarded as a magician for his demonstrations in King Arthur’s court, scientific knowledge is contingent upon a particular era in time.
Kuhn’s view of the history of science recognizes that what passes for “knowledge” is subject to revision and conventional science restricted by its own parameters. The scientific timeline is neither static nor perpetually expanding as we endlessly acquire new knowledge. Paradigm shifts are so radical it is inappropriate to hold theories from one era to the standards of another. According to Kuhn, true scientific advancement replaces obsolete principles with new ways of thinking that revolutionize our view of the world.
See also Aquinas and Augustine; Aristotle and Plato;
Bruno and Nicholas of Cusa; Copernicus, Nicolaus; Darwin and Aristotle; Einstein and Newton; Galilei, Galileo; Hegel and Kant; Nietzsche and Heraclitus
Fuller, S. (2000). Thomas Kuhn: A philosophical history for our times. Chicago: University of Chicago Press.
Horwich, P. (Ed.). (1993). World changes: Thomas Kuhn and the nature of science. Cambridge: MIT Press.
Kuhn, T. (1959). The essential tension: Tradition and innovation in scientific research. In E. C. Taylor (Ed.).
The third (1959) University of Utah Research Conference on the Identification of Scientific Talent (pp. 162-174). Salt Lake City: University of Utah Press.
Kuhn, T. (1962). The structure of scientific revolutions. Chicago: University of Chicago Press.