This book offers an inside look into the notoriously tumultuous, professional relationship of two great minds: Karl Popper and Paul Feyerabend. It collects their complete surviving correspondence (1948-1967) and contains previously unpublished papers by both. An introduction situates the correspondence in its historical context by recounting how they first came to meet and an extensive editorial apparatus provides a wealth of background information along with systematic mini-biographies of persons named. Taken together, the collection presents Popper and Feyerabend's controversial ideas against the background of the postwar academic environment. It exposes key aspects of an evolving student-mentor relationship that eventually ended amidst increasing accusations of plagiarism. Throughout, readers will find in-depth discussions on a wide range of intriguing topics, including an ongoing debate over the foundations of quantum theory and Popper's repeated attempts to design an experiment that would test different interpretations of quantum mechanics. The captivating exchange between Feyerabend and Popper offers a valuable resource that will appeal to scientists, laymen, and a wide range of scholars: especially philosophers, historians of science and philosophy and, more generally, intellectual historians.

Paul Feyerabend ranks among the most exciting and influential philosophers of science of the twentieth century. This reconstruction of his developing ideas combines historical and systematic considerations. Part I examines the three main influences on Feyerabend's philosophical development: Wittgenstein's later philosophy, Popper critical rationalism and Ehrenhaft's experimental effects. Part II focuses on Feyerabend's development and use of the notion of incommensurability at the heart of his philosophical critiques, and investigates his relation to realism. Feyerabend initially developed the notion of incommensurability from ideas he found in Duhem. He used the notion of incommensurability to attack many different forms of conceptual conservativism in philosophy and the natural sciences. He argued against many views on the grounds that that they would constrain the freedom necessary to develop alternative points of view, and thereby hinder scientific advance. Contrary to widespread opinion, he was never a scientific realist. Part III reconstructs Feyerabend's pluralistic conception of knowledge in the context of his pluralistic philosophical method. Feyerabend was a philosophical pluralist, who practiced pluralism in pursuit of progress.