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. (shrink)

One of the tasks with which communication engineers are presented is that of devising a mechanism by which a significant sequence of words, a message, produced by somebody, the sender of the message, is reproduced at some other place, with the shortest practical time lag. The reproduction must be such that the receiver of the message will be able to understand what the sender meant by his message, at least, if he knows the sender's language. The following illustration is typical: (...) A writes on a sheet of paper “I love you” and wishes that B, 3000 miles away, should become aware of the full content of this message, with little delay and at a low cost. There will be institutions, in a capitalistic society, which will compete with each other in providing A, for a price, with the required service. Those companies which perform these services most satisfactorily, i.e., with an overall better combination of faithfulness, time lag, and cost, will get the job. The executives of these companies will hire engineers and put them to work on improving this overall combination. (shrink)

Foundations of Set Theory discusses the reconstruction undergone by set theory in the hands of Brouwer, Russell, and Zermelo. Only in the axiomatic foundations, however, have there been such extensive, almost revolutionary, developments. This book tries to avoid a detailed discussion of those topics which would have required heavy technical machinery, while describing the major results obtained in their treatment if these results could be stated in relatively non-technical terms. This book comprises five chapters and begins with a discussion of (...) the antinomies that led to the reconstruction of set theory as it was known before. It then moves to the axiomatic foundations of set theory, including a discussion of the basic notions of equality and extensionality and axioms of comprehension and infinity. The next chapters discuss type-theoretical approaches, including the ideal calculus, the theory of types, and Quine's mathematical logic and new foundations; intuitionistic conceptions of mathematics and its constructive character; and metamathematical and semantical approaches, such as the Hilbert program. This book will be of interest to mathematicians, logicians, and statisticians. (shrink)

Subjects were requested to choose between gambles, where the outcome of one gamble depended on a single elementary event, and the other depended on an event compounded of a series of such elementary events. The data supported the hypothesis that the subjective probability of a compound event is systematically biased in the direction of the probability of its components resulting in overestimation of conjunctive events and underestimation of disjunctive events. Studies pertaining to this topic are discussed.

Neste artigo, Bar-Hillel e Carnap apresentam pela primeira vez as ideias básicas de uma teoria da informação semântica. O conceito de informação, baseado em sentença declarativa em uma dada linguagem, é definido pelo conteúdo descritivo expresso pelas sentenças. A quantidade de informação é calculada com base em um conjunto de funções lógicas probabilísticas sobre conjuntos de conteúdos descritíveis. Esta teoria tem aplicabilidade dedutiva e indutiva, significando um marco para o desenvolvimento das teorias filosóficas da informação.