Hans Reichenbach

Born Sept. 26, 1891, in Hamburg; died Apr. 9, 1953, in Los Angeles. German philosopher and logician.

Reichenbach was a professor of the philosophy of physics at the University of Berlin from 1926 to 1933. He founded both the journal Erkenntnis (Knowledge) and The International Encyclopedia of Unified Science. After the fascist regime became established in Germany, Reichenbach emigrated, first to Turkey and then to the USA. He was a professor of philosophy at the University of Istanbul from 1933 to 1938 and at the University of California from 1938 to 1953.

Reichenbach was a proponent of logical positivism. In his philosophical views he was close to materialism. He maintained that although physical objects are apprehended through sense impressions, it does not follow that these objects are reducible to impressions. He considered the major argument supporting the existence of the external world to be objective laws of causation, whose cognition is the aim of science. The problem of causality and the analysis of the ontological nature and logical structure of causal relationships constituted the nucleus of Rei-chenbach’s studies in philosophy and logic. These works dealt with the relationship between causality and probability and with dynamic and statistical scientific laws, temporal direction, and causal networks. Reichenbach assumed that causality was the objective relationship of real phenomena, although in a number of his earlier works he confused the ontological nature of causality with its subjective reflections in thought.

Reichenbach’s theory of knowledge rejected the ideal of veri-fiability, claiming that the establishment of any knowledge is best attained by probability logic. Adopting R. von Mises’ frequency interpretation of probability, Reichenbach applied the interpretation to logic and the theory of knowledge. He devised his own variant of a many-valued logic constructed as a special case of probability logic and used it to interpret logical and philosophic problems of quantum mechanics.