Ajdukiewicz’s Semantic Turn

Ajdukiewicz called his article Problemat idealizmu transcendentalnego w sformułowaniu semantycznym [The Semantic Version of Transcendental Idealism], published in “Przegląd Filozoficzny” in 1937, a “turning point” of his philosophical development. The aim of the paper is to present various aspects of this turn. Firstly, the historical and philosophical background of the 1937 paper is sketched. It includes the metaphilosophical position of the Lvov‑Warsaw School, and the development of methods applied in this group. Secondly, Ajdukiewicz’s ideas up to 1937 are outlined in order to present what the semantic turn consisted in. Next, the program of the semantic theory of knowledge is sketched, and the steps of Ajdukiewicz’s argumentation against transcendental idealism, with an emphasis on the use of metalogical and semantic results, are presented. Finally, Ajdukiewicz’s proposal is discussed from the methodological point of view.