Book excerpt: Born in Austria, Karl Popper (1902-1994) was one of the dominant philosophical thinkers of the 20th century. A ground-breaking thinker, he saw the essence of true science as being the readiness to submit theories to severe testing and to reject them when refuted by test. His first major book in 1935, The Logic of Scientific Discovery, marked him as a major analyst of science and was to have an enormous influence on the way people, including major scientists, came to think about the field. This collection is a timely assessment of the reactions to and abiding influence of Popper's work and the controversy it caused across many academic and political fields. The set includes early responses to Popper's work from sources difficult to obtain, and also two early reviews (by Carnap and Grelling) in translations specially prepared for this set. It is organised thematically and includes a substantial new introduction by the editor.