This volume constitutes the first collected edition of work so far done in illustrating an important new development in the philosophy of science, ‘the methodology of scientific research programmes’, with case studies drawn from the history of the physical sciences. This material, no doubt the forerunner of more complete accounts of the fit between Lakatos's ideas and scientific practice, is prefaced with an exposition of the methodology of scientific research programmes by its author, Imre Lakatos, who, sadly, died before the material was assembled in this volume; and there is a concluding critical appraisal both of Lakatos's theory and of the illustrations of it, by Paul Feyerabend.

Briefer versions of Clark's, Musgrave's and Worrali's papers were delivered at a conference on Research Programmes in Physics and Economics in Nafplion, Greece in September 1974. Lakatos's paper was published originally in Boston Studies in the Philosophy of Science, VTI; Zahar's paper was first published in the British Journal for the Philosophy of Science 24, 1973.

I should like to thank Miss Gillian Page and D. Reidel Publishing Company for permission to reprint Lakatos's paper, and the author and editor of the British Journal for the Philosophy of Science for permission to reprint Zahar's paper.