Thomas Samuel Kuhn (/kuːn/; July 18, 1922 – June 17, 1996) was an American historian and philosopher of science whose 1962 book The Structure of Scientific Revolutions was influential in both academic and popular circles, introducing the term paradigm shift, which has since become an English-language idiom.

[9] He also obtained MSc and PhD degrees in physics in 1946 and 1949, respectively, under the supervision of John Van Vleck,[10] after a short period of World War II war work with Van Vleck at Harvard's secret Radio Research Laboratory that included travel to England, France, and Germany.

[13] He was a Harvard Junior Fellow 1948–1951[11] and, as he states in the first pages of the preface to the second edition of The Structure of Scientific Revolutions, these three years of total academic freedom were crucial in allowing him to switch from studying physics to studying the history of science and philosophy of science.

[14] However, Conant's influence at Harvard declined rapidly over the course of the 50s and the general education program was refocused,[15] and Kuhn was rejected for tenure in 1957.

[11] At Berkeley, Kuhn served as director of the National Science Foundation project Sources for the History of Quantum Physics 1961–1964.

[19] In 1979 he joined the Massachusetts Institute of Technology (MIT) as the Laurance S. Rockefeller Professor of Philosophy,[21] remaining there until becoming emeritus in 1991.

[22] The Structure of Scientific Revolutions (SSR) was originally printed as an article in the International Encyclopedia of Unified Science, published by the logical positivists of the Vienna Circle.

[23] In this book, heavily influenced by the fundamental work of Ludwik Fleck (on the possible influence of Fleck on Kuhn see[24]), Kuhn argued that science does not progress via a linear accumulation of new knowledge, but undergoes periodic revolutions, also called "paradigm shifts" (although he did not coin the phrase, he did contribute to its increase in popularity),[25] in which the nature of scientific inquiry within a particular field is abruptly transformed.

Rather, they are concrete indices to the content of more elementary perceptions, and as such they are selected for the close scrutiny of normal research only because they promise opportunity for the fruitful elaboration of an accepted paradigm.

[28] The enormous impact of Kuhn's work can be measured in the changes it brought about in the vocabulary of the philosophy of science: besides "paradigm shift", Kuhn popularized the word paradigm itself from a term used in certain forms of linguistics and the work of Georg Lichtenberg to its current broader meaning, coined the term "normal science" to refer to the relatively routine, day-to-day work of scientists working within a paradigm, and was largely responsible for the use of the term "scientific revolutions" in the plural, taking place at widely different periods of time and in different disciplines, as opposed to a single scientific revolution in the late Renaissance.

[citation needed] Kuhn's work has been extensively used in social science; for instance, in the post-positivist/positivist debate within International Relations.

[29] This is because would-be scientists' worldviews are changed through rigorous training, through the engagement between what Kuhn calls 'exemplars' and the Global Paradigm.

According to Kuhn, "When scientists must choose between competing theories, two men fully committed to the same list of criteria for choice may nevertheless reach different conclusions.

[35][36] In their book, Andersen, Barker and Chen use some recent theories in cognitive psychology to vindicate Kuhn's mature philosophy.

In a scientific revolution, a new paradigm (or a new taxonomy) replaces the old one; by contrast, specialisation leads to a proliferation of new specialties and disciplines.

[38]Some philosophers claim that Kuhn attempted to describe different kinds of scientific change: revolutions and specialty-creation.

[41] Although they used different terminologies, both Kuhn and Michael Polanyi believed that scientists' subjective experiences made science a relativized discipline.

After the charge of plagiarism, Kuhn acknowledged Polanyi in the Second edition of The Structure of Scientific Revolutions.

[46] In 1983 he received the John Desmond Bernal Award from the Society for Social Studies of Science and in 1990 he became a corresponding fellow of the British Academy.