American philosopher of science. Born in Ohio, Kuhn was educated at Harvard as a physicist before his book The Structure of Scientific Revolutions (1962) became one of the most influential modern works of the history and philosophy of science. Like Alexandre Koyré (1892–1964) and the French writers Bachelard and Jean Cavaillès (1903–44), Kuhn stresses that the history of science is not a smooth progressive accumulation of data and successful theory, but the outcome of ruptures, false starts, and imaginative constraints that themselves reflect many different variables. In his account, science during a normal period works within a framework of assumptions called a paradigm, but in exceptional and revolutionary periods an old paradigm breaks down and after a period of competition is replaced by a new one. The process is something like a Gestalt switch, and has seemed to many to have disquieting implications for the rationality and objectivity of science. Kuhn's other books include The Copernican Revolution (1957) and Sources for the History of Quantum Physics (1967).