This volume is a collection of the lectures and discussions at an international colloquium organized by Unesco on the theme of Science and Synthesis to mark the occasion of the 10th anniversary of the death of both Einstein and Teilhard de Chardin, also the 50th anniversary of the theory of general relativity. Despite the great gulf which lies between the work of Einstein and Teilhard de Chardin, the coincidence in the dates provided an opportunity to examine the urge towards a synthesis of the scientific and philosophical approaches which lies at the very heart of the work of these two great men. It was, indeed, their common desire for an all-embracing concept of the universe which led them both to try to construct a cosmology for the modern world. So it seemed that the best way of honoring Einstein and Teilhard de Chardin was to arrange a free discussion of the current likelihood of effecting a syn thesis of scientific knowledge which would bring together some of today's most eminent scholars, inspired by the wish to make their research more meaningful by philosophic reflection. The resulting give and take of ideas would go far beyond mere commemoration; it would bring their ideas to life by setting them against the present state of science."

Information theory and cybernetics have developed along somewhat different lines in Europe and in the U. S. A. This book is to be seen as a contribution towards bridging the gap. Anyone who seeks to apply information theory in the fields of education and psychology very soon comes up against a central diffi culty: in the form in which it was developed by Shannon information theory excludes the semantic aspect. This problem is fundamental for in education, as in psychology, the semantic aspect is the very heart of the matter. Thus, while Attneave, Miller and Quastler, among others, successfully employed the concepts and units of measurement of in formation theory in the interpretation of the findings of experimental psychology, they were obliged to restrict their work to its syntactic and statistical aspects. Before we can make use of the methods and results of information we have to solve the central problem: How can theory in actual teaching, we measure the semantic information of a verbal message? The only way to do this is by extending the theory. A special concept has been deve loped for this purpose: subjective information. In place of an objectively measurable quantity (frequency of sign sequences) we set an empirically determined one: the subjective probability with which the recipient expects a certain sign sequence."