philosopher and educator who was a leading representative of the Vienna Circle and founder of the Berlin school of Logical Positivism, a movement that viewed logical statements as revealing only the basic structure of a priori mental categories and language. He contributed significantly to logical interpretations of probability theories, theories of induction, and the philosophical bases of science. He went to the United States in 1938, where he helped edit the Journal of Unified Science (formerly Erkenntnis), and wrote Elements of Symbolic Logic (1947) and The Rise of Scientific Philosophy (1951).