The papers presented here derive from the 4th International Confe: --ence on History and Philosophy of Science held in Blacksburg, Virginia, U. S. A., November 2-6, 1982. The Conference was sponsored by the I nternational Union of History and Philosophy of Science and Virginia Polytechnic Institute and State University (Virginia Tech). Particular thanks go to L. Jonathan Cohen, Secretary of the Union, as well as to Dean Henry Bauer of the College of Arts & Sciences, Wilfred Jewkes and the Center for Programs in the Humanities, Arthur Donovan and the Center for the Study of Science in Society and the Department of Philoso- phy and Religion at Virginia Tech. Not only did they come through with the necessat"y funds, but they were all always ready with a helping hand when things got confusing. Two additional groups of individuals require a special note of thanks. First, considerable appreciation is due the mem- bers of the Joint Commission of the I nternational Union of History and Philosophy of Science: Maurice Crosland, Risto Hilpinen and Vladimir Kirsanov. They were more than gen- erous in thei r advice and co-operation. The Local Organizing Committee (Kenneth Alpern, Roger Ariew, Arthur Donovan, Larry Laudan, Ann La Berge, Duncan Porter, Eleonore Stump and Dennis Welch) not only demon- strated efficiency and insured a pleasant stay for' all participants, but also went out of their way on numerous occasions to make everyone feel at home.