Frege’s Way Out. Stanisław Leśniewski’s Unpublished Archival Document (1938)

This paper presents the transcription of a previously unknown archival document: Stanisław Leśniewski, The Basic Scheme of a Proof for the Theorem “a = b” in the Reformed Frege’s System [1938], written in German and stored in one of Berlin’s archives. It was sent to Heinrich Scholz, professor at the University of Münster (Germany). Nevertheless, it is kept in the legacy of Karl Schröter, who was previously Scholz’s student and co-worker. Furthermore, we provide introductory remarks on the problem of Russell’s antinomy in Gottlob Frege’s logical system from Basic Laws of Arithmetic, its subsequent correction, and the origin of the term Frege’s way out. We conclude that the document Basic Scheme of a Proof sheds new light on Frege’s logical system correction given by him in the Afterword to the second volume of the book.