Thomas Samuel Kuhn | Biography

Thomas Samuel Kuhn was an American historian and philosopher of science. He found that basic ideas about how nature should be studied were dogmatically accepted in normal science, then increasingly questioned, and overthrown during scientific revolutions. Born in Cincinnati, Ohio, in 1922, Thomas Kuhn was trained as a physicist but became an educator after receiving his Ph.D. in physics from Harvard in 1949. He taught the history of science at Harvard, University of California/Berkeley, Princeton, and Massachusetts Institute of Technology (MIT). He was a member or director of many professional organizations and received many awards.

Kuhn was best known for debunking the common belief that science develops by the accumulation of individual discoveries. In the summer of 1947 something happened that shattered the image of science he had received as a physicist. He was asked to interrupt his doctorate physics project to lecture on the origins of Newton's physics. Predecessors of Newton such as Galileo and Descartes were raised within the Aristotelian scientific tradition. Yet Kuhn was shocked to find in Aristotle's physics precious little with which a Newtonian could agree or of which he could even make sense. He asked himself how Aristotle, so brilliant on other topics, could be so confused about motion and why his views on motion were taken so seriously by later generations. One hot summer day while reading Aristotle, Kuhn had a brainstorm. "Suddenly the fragments in my head sorted themselves out in a new way, and fell into place together." He realized that he had been misreading Aristotle by assuming a Newtonian point of view. Taught that science progresses cumulatively, he had sought to find what Aristotle contributed to Newton's mechanics. This effort was wrong-headed because the two men had basically different ways of approaching the study of motion.

For example, Aristotle's interest in change in general led him to regard motion as a change of state, whereas Newton's interest in elementary particles, thought to be in continuous motion, led him to regard motion as a state. That continuous motion requires explanation by appeal to some force keeping it in motion was taken as obvious by Aristotle. But Newton thought that continued motion at a certain speed needed no explanation in terms of forces. Newton invoked the gravitational force to explain acceleration and advanced a law that an object in motion remains in motion unless acted upon by an external force.

This discovery turned Kuhn's interest from physics to the history of physics and eventually to the bearing of the history of science on the philosophy of science. His working hypothesis that reading a historical text requires sensitivity to changes in meaning provided new insight into the work of such physicists as Boyle, Lavoisier, Dalton, Boltzmann, and Plank. This hypothesis was a generalization of his finding that Aristotle and Newton worked on different research projects with different starting points which eventuated in different meanings for basic terms such as "motion" or "force." Most people probably think that science has exhibited a steady accumulation of knowledge. But Kuhn's study of the history of physics showed this belief to be false because different research traditions have different basic views.

Especially striking to Kuhn was the fact that scientists rarely argued explicitly about these basic research decisions. Scientific theories were popularly viewed as based entirely on inferences from observational evidence. But no amount of experimental testing can dictate these decisions because by their nature they are logically prior to testing. What, if not observations, explains the consensus of a community of scientists within the same tradition at a given time? Kuhn boldly conjectured that they must share common commitments, not based on observation or logic alone, in which these matters are implicitly settled. Most scientific practice is a complex mopping-up operation, based on group commitments, which extends the implications of the most recent theoretical breakthrough. Here, at last, was the concept for which Kuhn had been searching: the concept of normal science takes for granted a paradigm, the locus of shared commitments.

In 1962 Kuhn published his landmark book on scientific revolutions, which was eventually translated into sixteen languages and sold over a million copies. He coined the term "paradigm" to refer to accepted achievements such as Newton's Principia which contain examples of good scientific practice. These examples include law, theory, application, and instrumentation. They function as models for further work. The result is a coherent research tradition. In his postscript to the second edition, Kuhn pointed out two senses of paradigm used in his book. In the narrow sense, it is one or more achievement wherein scientists find examples of the kind of work they wish to emulate, called "exemplars." In the broad sense it is the shared body of preconceptions controlling the expectations of scientists, called a "disciplinary matrix." Persistent use of exemplars as models gives rise to a disciplinary matrix that determines the problems selected for study and the sorts of answers acceptable to the scientific community.

Using the paradigm concept, Kuhn developed a theory of scientific change. A tradition is pre-scientific if it has no paradigm. A scientific tradition typically passes through a sequence of normal science-crisis-revolution-new normal science. Normal science is puzzle-solving governed by a paradigm accepted uncritically. Difficulties are brushed aside and blamed on the failure of the scientist to extend the paradigm properly. A crisis begins when scientists view these difficulties as stemming from their paradigm, not themselves. If the crisis is not resolved, a revolution sets in, but the old paradigm is not given up until it can be replaced by a new one. Then new normal science begins and the cycle is repeated. Just when to accept a new paradigm and when to stick to the old one is a matter not subject to proof, although good reasons can be adduced for both options. Scientific rationality is not found in rules of scientific method but in the collective judgment of the scientific community. We must give up the notion that science progresses cumulatively toward the truth about reality; after a revolution it merely replaces one way of seeing the world with another.

Kuhn died June 17, 1996, at his home in Cambridge, Massachusetts. Kuhn transformed the image of science by emphasizing that it is both a social and rational process. His theory has profound implications for any area of knowledge, since scientific knowledge is generally taken as the benchmark to which other forms of knowledge are compared. Moreover, the terminology of "paradigm" and "paradigm shifts" has been incorporated into the study of knowledge into other fields of study.