Kazimierz Ajdukiewicz on transcendental idealism from a semantic point of view

In a paper entitled A Semantical Version of the Problem of Transcendental Idealism, Kazimierz Ajdukiewicz gives a very impressive analysis of transcendental idealism. He approaches the matter using the tools of formal semantics developed by Alfred Tarski and draws a rather surprising conclusion. According to Ajdukiewicz, the idealist position, claiming that the world around us is ontologically dependent on our cognitive activity can be shown to be implausible on purely logical grounds. It is worth taking a closer look at this insightful argument, since Ajdukiewicz’s analysis, if sound, has a relevance reaching far beyond purely historical questions concerning the right interpretation and proper assessment of past idealist doctrines. These days various species of (mostly local) idealism are thriving under such labels as ‘anti realism’ or ‘pragmatism’. Ajdukiewicz’s venerable paper goes to the very core of many contemporary metaphysical discussions.