THE welcome co-operation between science and philosophy, which has become a distinctive feature of our time, is further illustrated by the appearance of a new quarterly, Philosophy of Science, which is published by the Philosophy of Science Association in the United States (Baltimore: Williams and Wilkins Co.; London: Bailliere, Tindall and Cox. 6s. 9d.). This interesting publication sets itself the useful task of giving an organised expression to the growing interest among philosophers and scientific workers in classifying, and perhaps unifying, the programmes, methods and results of the disciplines of philosophy and of science. With this object in view, the editor, Prof. W. M. Malisoff, proposes as a research programme, the analysis of meaning, symbolism, definition, axioms and postulates, the study of the nature and formulation of theoretical principles, and questions of method and of the structure and hierarchy of the sciences. The first issue of the new journal contains a remarkable series of papers; among the contributors are Prof. J. B. S. Haldane on “Quantum Mechanics as a Basis for Philosophy”, D. J. Struik on “The Foundations of the Theory of Probabilities”, Rudolf Carnap on “The Character of Philosophic Problems”. The excellent presentation of the journal and the eminence of its contributors give an added value to its object and method which, no doubt,.will appeal equally to scientific workers and to philosophers.