The Structure of Scientific Revolutions by Thomas S. Kuhn

First published: 1962

Type of Philosophy: Epistemology, philosophy of science

Context

Knowledge of nature’s workings and the ability to put that knowledge to practical use depends upon the doctrine of empiricism, the development of ideas on the basis of experimentation and observation. This doctrine itself evolved from the declining reliance during the Renaissance upon Christian doctrine and the Bible to explain new phenomena and increasing emphasis upon human experience as a source of knowledge. During the early twentieth century, a group of logical positivists, including England’s Bertrand Russell and Austria’s Ludwig Wittgenstein, rejected all metaphysical doctrines and held that true knowledge comes from human experience alone, particularly via its most rigorously controlled form, the scientific method: the accumulation of data under controlled conditions, construction of theories on the basis of the data, and verification of theories by experimentation and observation in accordance with objective standards of logic. Although subsequent adherents to this school often called themselves logical empiricists and insisted that theories cannot really be verified, only falsified, the underlying assumption is that the history of science has been the unbroken accumulation of knowledge in an orderly, unified sequence.

In The Structure of Scientific Revolutions, Thomas S. Kuhn disagrees with the logical positivists almost completely. Although he also believed that scientists aim for an increasingly accurate understanding of nature, he found that a community of scientists, such as physicists or biologists, often goes through periods of divisive disagreement over theory and the nature of data. The final triumph of one faction of a scientific field over another involves the interactions of people. Science is a social process as well as a knowledge-gathering enterprise.

Kuhn concentrates on the structure of scientific development in order to offer a schematic explanation applicable not only to individual disciplines and subdisciplines but also to science as a whole. Kuhn concerns himself with only the pure sciences and not the social sciences or applied sciences, and he specifically addresses the cognitive (or epistemic) function of science. He does not explore science’s ultimate value or truth or its place in human culture.

A Challenge to the History of Science

The introduction challenges the view of the history of science that predominated before publication of The Structure of Scientific Revolutions in 1962. That view held science to be a sequence of datable discoveries, inventions, and theories. It served a small but attitude-building function in science education because it formed part of the received knowledge in textbooks. Textbooks covered contemporary knowledge but not its development, seldom explaining scientific history in depth. Historians such as Alexander Koyré, Kuhn points out, were unable to support the development-by-accumulation view of science textbooks because it was sometimes impossible to determine precisely who made a discovery or when. If such questions as who or when were not always relevant, then a continuous, orderly development is at best a conveniently fictional image of science. Kuhn promises that his book will offer a new image drawn from a close examination of history.

In the first chapter, Kuhn argues that the methods of science alone cannot guarantee a unique answer to a question about nature. A researcher who is versed in the standards of evidence and logic in science but who is not trained in a particular discipline such as chemistry might devise any number of mutually incompatible answers to a problem in chemistry by applying standard scientific techniques. It is prior experience in a discipline, gained from scientists’ education and their professional careers, that guides a researcher to an answer that is useful to the discipline and compatible with it. Therefore, specialized training helps determine the types of questions that scientists will ask about the aspect of nature they study and the sorts of answers that they are likely to produce.

The Cycle of Science

Science, however, does not automatically settle into a routine of scientific training followed by application of textbook-conveyed knowledge, especially when the discipline is new, Kuhn explains in the second chapter. History reveals many instances in which a discipline consisted of several schools of thought at odds with each other about basic conceptions. During the late Renaissance, for example, some astronomers held, following Ptolemy, that Earth was the center of the universe and everything revolved around it; followers of Tycho Brahe thought Earth was the center and the Sun revolved around it, but that everything else revolved around the Sun; and Copernicans placed the Sun at the center, around which Earth and the other planets revolved. All three schools derived their distinct cosmologies in ways generally compatible with the same mathematics and methods of observation. What distinguishes such rival schools, Kuhn proposed, is not that one is more or less scientific than another but that each has a view incommensurable with the others. Incommensurability, or untranslatability, is a key term in Kuhn’s philosophy: The basic conceptions of one scientific school do not correspond to those of another. When proponents of one school argue with those of another, the two sides are apt to talk past each other rather than communicate meaningfully.

Eventually, one theory prevails. Elaborated on and passed on by professional education, it provides succeeding generations of researchers with a shared set of assumptions, theory, facts, and methods with which to analyze new problems and phenomena. Kuhn termed this shared professional knowledge a “paradigm.” In the third through fifth chapters, he discusses the paradigm-guided pursuit of scientific knowledge. It inaugurates the mature phase of a science, during which normal, or routine, science reigns. Specialists agree on what constitutes an acceptable problem, how to go about investigating it, and how to fit data to established theory in solving it. Most scientists spend their entire careers posing and solving problems in accordance with an established paradigm, assuming that they have a fundamental grasp of how nature behaves.

In chapters 6 through 8, a key section of The Structure of Scientific Revolutions, Kuhn considers what happens when a paradigm fails to support a scientist’s assumption. First, evidence of a fundamental novelty accumulates from experiments, or equipment behaves in an unexpected way that the scientific establishment cannot explain. Newtonian mechanics, for example, could not explain experimenters’ failure to detect a theoretical all-pervading ether, and classical physicists were perplexed by the seemingly paradoxical behavior of light as both a particle and a wave. The impulse of most scientists is to suppress such anomalies, Kuhn says, in order to defend the assumption in their paradigm that the anomalies appear to contradict. However, when normal science repeatedly fails to satisfy professional expectations, anomalies cannot be suppressed for long. A young scientist, or one new to a discipline, inevitably reexamines the evidence from a fresh, nontraditional viewpoint. In his special theory of relativity, Albert Einstein demonstrated that no ether need exist in order to explain the dynamics of light; ether thereby vanished as a scientific problem. Quantum mechanics grew out of the puzzle over light’s dual nature and accepted that light can behave like a particle or a wave, depending upon how it is observed. New theoretical concepts, such as Einstein’s positing light as a constant and the uncertainty principle of quantum mechanics, are difficult for many scientists to accept.

A period of crisis follows for the discipline. Scientists divide into schools, and controversy over basic assumptions prevails. One faction gradually dominates and establishes a new set of commitments for the profession that serves as the basis for practicing the science. That is, a new paradigm takes over. However, the new paradigm does not just supply a new theory. It forces the reevaluation of the prior paradigm and the knowledge it had produced because it is fundamentally incompatible with the new viewpoint. The new paradigm transforms the imagination of scientists. This process of transformation is a scientific revolution.

The cycle of normal science, crisis, and paradigm shift is not incremental, as previous philosophy of science assumed, and because its course is not predictable, it is not strictly logical. Kuhn admits that there is some arbitrariness involved in starting a revolution and in the shape the new paradigm will take because that depends upon unexpected, accidental discoveries and the unorthodox methods of innovators. Nevertheless, the innovations cannot be entirely arbitrary. They must be more fruitful in problem solving than the previous paradigm. Accordingly, succeeding paradigms are better and better approximations of truths about nature.

In the ninth and tenth chapters of The Structure of Scientific Revolutions, Kuhn illustrates his structural scheme for scientific revolutions with four signal episodes in the history of science: the cosmological model of Nicolaus Copernicus in the Renaissance, the mechanics of Sir Isaac Newton and the new chemistry of Anton Lavoisier during the Enlightenment, and the relativistic dynamics of Einstein early in the twentieth century. Each, he contends, not only changed science fundamentally but also eventually changed the worldview of Western culture.

Textbooks and the Goal of Science

In chapter 12, Kuhn returns to the influence of science textbooks, which more than any other single influence imbue scientists with the traditional paradigm of their profession. Textbooks before The Structure of Scientific Revolutions implied that a paradigm was the logical outcome of the discoveries and hypotheses that led to it by ignoring those discoveries and ideas that did not contribute to it. Thereby, textbooks gave the appearance of continuity, which Kuhn calls “unhistoric stereotypes,” and obscured the revolutionary ferment that led to a paradigm.

In the final chapter, Kuhn takes up a related, troubling question: How can the development of science through revolutions, in which some degree of arbitrariness exists, be reconciled with the progress of science in uncovering useful truths about nature? Kuhn offers only the outline of an answer, admitting that much more study of scientific communities is required to settle the question. His discussion draws upon an analogy with Darwinian evolution. Just as there is no ultimate goal of biological evolution, according to Charles Darwin, so Kuhn suggests there is no goal for science. Instead, the equivalent of natural selection takes place from competition among rival schools of thought, a process that produces the fittest way to conduct science until something new in the environment of scientific evidence challenges it. Science grows increasingly articulated and specialized (the equivalent of speciation) as it evolves.

No single modern book about the philosophy and history of science so deeply stirred up controversy and inspired further analysis as The Structure of Scientific Revolutions. The challenge to long-standing assumptions about science history prompted such heated discussions among philosophers of science and scientists themselves that science history is said to have pre-Kuhnian and post-Kuhnian periods. Regularly, books and articles appeared and conferences were held about the book, and Kuhn forcefully defended and elaborated his ideas until his death in 1996. One colleague predicted that Kuhn’s book would be one of the few philosophical monographs of the twentieth century to be remembered in centuries to come.

The Structure of Scientific Revolutions also had a deep effect on popular culture. By the late 1960’s, when the book became commonly assigned reading in philosophy courses, antiestablishment fervor among college students and intellectuals was strong. Because Kuhn recognized that some arbitrariness affects science, readers searching for reasons to reject authority misread Kuhn to mean that all human systems are arbitrary—that everything is relative—and so no unassailable truths create authority. Despite Kuhn’s objections, antiscience intellectuals continued to cite The Structure of Scientific Revolutions. At the same time, terms such as “paradigm” and “scientific revolution” entered the general intellectual idiom.

Principal Ideas Advanced

•Science evolves not continuously but in periods of normal research punctuated by crises in theory that produce a revolution, which in turn resolves into another period of normal research.

•Scientists within a discipline form a community whose education has united them in relying on a certain paradigm—a collection of theories, facts, and methods—that guides them in discovering and solving problems.

•A revolution entails a paradigm shift, which involves a change in the meaning of basic concepts and terminology.

•Rival scientific schools within a discipline cannot effectively communicate with each other because the assumptions and theories of each are incommensurable, or untranslatable.

Bibliography

Giere, Ronald N. Explaining Science: A Cognitive Approach. Chicago: University of Chicago Press, 1988. This book surveys the philosophical theories of science and includes an extensive review of Kuhn’s philosophy. Many of the discussions are largely developed from Kuhn’s concept of revolutions in science.

Horgan, John. “Reluctant Revolutionary.” Scientific American 264, no. 5 (May, 1991): 40-9. In an interview, Kuhn reveals his frustration with those who misused or misinterpreted his ideas about scientific revolutions. He discusses modifications he made to his theory, particularly in the definitions of “paradigm” and “incommensurability.” Horgan depicts both Kuhn’s personality and ideas with clarity.

Horwich, Paul, ed. World Changes: Thomas Kuhn and the Nature of Science. Cambridge, Mass.: MIT Press, 1993. An introduction by the editor and essays by nine scholars discuss how Kuhn’s ideas differ from those of previous philosophers. The essays take historical or philosophical approaches in their arguments. In “Afterwords,” Kuhn comments on the essays, refining his views about incommensurability and defending himself against charges of relativism and antirealism.

Hoyningen-Huene, Paul. Reconstructing Scientific Revolutions: Thomas S. Kuhn’s Philosophy of Science. Chicago: University of Chicago Press, 1993. The author “reconstructs” Kuhn’s theory of scientific development as articulated in The Structure of Scientific Revolutions. His purpose is to clarify the fundamentals of the theory and end the confusion produced by the diverse interpretations of Kuhn’s vaguely defined terms. This volume is most helpful for readers familiar with the controversies produced by Kuhn’s book.

Margolis, Howard. Paradigms and Barriers: How Habits of Mind Govern Scientific Beliefs. Chicago: University of Chicago Press, 1993. Margolis applies his own analysis of cognition to Kuhn’s concept of the paradigm shift. Specifically, Margolis finds that habits of mind, pervasive and normally beneficial, sometime pose barriers in the face of novel phenomena or theories. A paradigm shift occurs when the barrier is overcome and new habits of mind replace old. His argument, he insists, reveals that relativism has a limited role in the methods of science.

O’Hear, Anthony. Introduction to the Philosophy of Science. Oxford, England: Clarendon Press, 1989. O’Hear discusses Kuhn’s paradigm-centered theory at length and somewhat unsympathetically. He specifically compares Kuhn’s ideas with those of Karl Popper and examines the historical evidence upon which Kuhn relied. The book, which summarizes the philosophy of science as a whole, is readable and well-suited to readers new to the subject in general and Kuhn in particular.

Thagard, Paul. Conceptual Revolutions. Princeton, N.J.: Princeton University Press, 1992. Thagard bases his own theory of scientific revolutions on Kuhn’s ideas. He seeks to add a psychological and computational approach for analyzing conceptual transformations, hierarchies, combinations, structures, sources, and explanatory coherence. In so doing, he summarizes Kuhn’s work and shows its wide influence.