Paul Karl Feyerabend was an Austrian-born philosopher of science best known for his work as a professor of philosophy at the University of California, Berkeley, where he worked for three decades (1958–1989).

His life was a peripatetic one, as he lived at various times in England, the United States, New Zealand, Italy, Germany, and finally Switzerland. His major works include Against Method (published in 1975), Science in a Free Society (published in 1978) and Farewell to Reason (a collection of papers published in 1987). Feyerabend became famous for his purportedly anarchistic view of science and his rejection of the existence of universal methodological rules. He is an influential figure in the philosophy of science, and also in the sociology of scientific knowledge.