Paul Feyerabend ranks among the most exciting and influential philosophers of science of the twentieth century. This book reconstructs Feyerabend’s pluralistic conceptions of knowledge and philosophy as they developed from the late 1940s through to his infamous Against Method. It combines a historical narrative of the main influences on his developing ideas with a systematic investigation of their merits. It presents Feyerabend as a philosopher who promoted pluralism in the pursuit of progress.