After a stay of one year at the University of Oxford in 1954 he returned to the University of Innsbruck where he was appointed as associate professor for philosophy in 1956. After stays as visiting professor at the Universities of Kiel and Bonn he received a call from the Ludwig Maximilian University of Munich. Here in 1958 he was appointed professor for philosophy, logic, and philosophy of sciences and became director of the "Seminar II". Except for two stays at as a visiting professor in 1962/63 and 1964 at the University of Pennsylvania he remained in Munich and ran there a center for analytical philosophy until his retirement in 1990. From 1977 to 1979 he also was dean of the faculty for philosophy, philosophy of science, and statistics.