The history of modern modal logic is too often presented as an American success story that started with the work of the Harvard philosopher C. I. Lewis, while prewar modal logic research in Europe is passed off as a side-show of well-intended failures. As a contribute towards correcting this picture, we carefully analyze and reconsider Oskar Becker’s pioneering work On the Logic of Modalities (1930), highlighting its influence on the early development of modal logic in the decade 1930 - 1940.weiterlesen