A provocative contribution to the new approach to the history and philosophy of science which emphasizes the role of radically new paradigms in scientific revolutions. While normal science proceeds as puzzle-solving within a relatively fixed paradigm, scientific crises lead to new paradigms where data, scientific problems, procedures, and standards for solutions are all altered. Scientific revolutions do not simply modify our understanding of a world which exists independently--they change the data and the world in which the scientist works. The essay (...) is filled with fascinating historical interpretations, though the analysis of the concept of a paradigm and scientific revolution is more suggestive than rigorous.--R. J. B. (shrink)