Yehoshua Bar-Hillel (1915-1975) was one of the leading intellectuals of Israel and of the world. His work ranged over mathematics, applied logic, communication theory, analytic philosophy, philosophy of science, and linguistics. Creative, patient, attentive, and critical, Bar-Hillel was a superb philosopher. In addition, how humane he was may be learned from the memorial tributes to him which initiate this volume. Bar-Hillel was born in Vienna, and came to Israel, then Palestine, in 1933. He took his M. A. (1938) and Ph. D. (1949) at the Hebrew University of Jerusalem, where his subsequent career continued, as Research Fellow (1949-53), Senior Lecturer in Philosophy (1953-58), Associate Professor of Philosophy (1958-61), and Professor of Logic and Philosophy of Sci­ ence (1961-75). He was often abroad as visiting professor (Berkeley, 1960- 61; Michigan, 1965; La Jolla, 1966-67; Konstanz, 1971; Berlin, 1972), or as a research scholar, notably at the M. lT. Research Laboratory for Elec­ tronics during the early 1950's. Bar-Hillel was the Secretary and guiding spirit of the Organizing Committee for the 3rd International Congress for Logic, Methodology and Philosophy of Science, held in Jerusalem in 1964. During 1966-68, he was President of the Division of Logic, Method ology and Philosophy of SCience of the International Union of History and Philosophy of Science, and in 1967 President of the International Union. From 1963 he was a Member of the Israel Academy of Sciences and Humanities.