Thomas Kuhn's Structure of Scientific Revolutions became the most widely read book about science in the twentieth century. His terms 'paradigm' and 'scientific revolution' entered everyday speech, but they remain controversial. In the second half of the twentieth century, the new field of cognitive science combined empirical psychology, computer science, and neuroscience. In this book, the recent theories of concepts developed by cognitive scientists are used to evaluate and extend Kuhn's most influential ideas. Based on case studies of the Copernican revolution, the discovery of nuclear fission, and an elaboration of Kuhn's famous 'ducks and geese' example of concept learning, the volume offers new accounts of the nature of normal and revolutionary science, the function of anomalies, and the nature of incommensurability.