The International Encyclopedia of Unified Science (IEUS) was a series of publications devoted to unified science. The IEUS was conceived at the Mundaneum Institute in The Hague in the 1930s, and published in the United States beginning in 1938. It was an ambitious project that was never completed. The IEUS was an output of the Vienna Circle to address the "growing concern throughout the world for the logic, the history, and the sociology of science..." Only the first section Foundations of the Unity of Science (FUS) was published; it contains two volumes for a total of nineteen monographs published from 1938 to 1969.

International Congresses for the Unity of Science

Creation of the IEUS was facilitated by the International Congresses for the Unity of Science organized by members of the Vienna Circle. After a preliminary conference in Prague in 1934, the First International Congress for the Unity of Science was held at the Sorbonne, Paris, 16–21 September 1935. It was attended by about 170 people from over twenty different countries. With the active involvement of Kazimierz Ajdukiewicz (Poland), Susan Stebbing (England), and Federigo Enriques (Italy) the scope of the project for an IEUS was considerably expanded. The congress expressed its approval of the planned IEUS as proposed by the Mundaneum, and further set up a committee to plan future congresses. This committee included the following members: The Third International Congress for the Unity of Science, which was devoted exclusively to the IEUS, was held in Paris, 29–31 July 1937.

Volume I

Encyclopedia and Unified Science (FUS I-1) Otto Neurath, Niels Bohr, John Dewey, Bertrand Russell, Rudolf Carnap, and Charles Morris Foundations of the Theory of Signs (FUS I-2) Charles Morris Foundations of Logic and Mathematics (FUS I-3) Rudolf Carnap Linguistic Aspects of Science (FUS I-4) Leonard Bloomfield Procedures of Empirical Science (FUS I-5) Victor F. Lenzen Principles of the Theory of Probability (FUS I-6) Ernest Nagel Foundations of Physics (FUS I-7) Philipp Frank Cosmology (FUS I-8) E. Finlay-Freundlich Foundations of Biology (FUS I-9) Felix Mainx The Conceptual Framework of Psychology (FUS I-10) Egon Brunswik

Volume II

Foundations of the Social Sciences (FUS II-1) Otto Neurath The Structure of Scientific Revolutions (FUS II-2) Thomas S. Kuhn Science and the Structure of Ethics (FUS II-3) Abraham Edel Theory of Valuation (FUS II-4) John Dewey The Technique of Theory Construction (FUS II-5) Joseph H. Woodger Methodology of Mathematical Economics and Econometrics (FUS II-6) Gerhard Tintner Concept Formation in Empirical Science (FUS II-7) Carl G. Hempel The Development of Rationalism and Empiricism (FUS II-8) George De Santillana, Edgar Zilsel The Development of Logical Empiricism (FUS II-9) Joergen Joergensen Bibliography and Index (FUS II-10) Herbert Feigl, Charles Morris

Influence

Historian David Hollinger argued that the IEUS was a less comprehensive account of the sciences of the time than it could have been, and was especially weak in the social sciences. Hollinger noted that the Encyclopaedia of the Social Sciences, published around the same time, provided a much more comprehensive account of the social sciences: "The Encyclopedia of the Social Sciences (12 vols., New York, 1933–1937) was a prodigious endeavor brought to successful completion by Alvin Johnson. This encyclopedia is a much more important episode in the history of thought than The International Encyclopedia of Unified Science yet has attracted much less attention from historians than the abortive enterprise led by Neurath." Hollinger also said that the scholarly journal Philosophy of Science, founded in 1934, provided a much more inclusive perspective on the sciences in those years than did the IEUS.