Hans Reichenbach (1891–1953) was the leader of “logical empiricism.” He was born in Hamburg and studied mathematics, physics, logic, and philosophy. He became a professor of philosophy of science at the University of Berlin and was a close associate of Albert Einstein. He founded Erkenntnis with Rudolf Carnap (1891–1970), which was the premier journal of scientific philosophy in the 1930s.

As with thousands of other Jews at the time, Reichenbach had to leave Germany in 1933. He first went to Istanbul before settling down at the University of California at Los Angeles. His main works include Experience and Prediction (1938), The Theory of Probability (1939–1949), and the posthumous The Direction of Time (1956).