Jan Lukasiewicz’s Account of the Intuitionistic Propositional Logic

Abstract

The aim of the article was to show Lukas iewicz’s programmatic theses that are contained mainly in his work On the In tu itionistic Propositional Logic and concerning first of all the connections between the intuitionistic and classical sentential calculi. It was also shown that in the same article Lukasiewicz did not put into effect the programmatic theses he proclaimed although he thought that he fulfilled the task formulated in this way. Moreover, an attempt was made to complement some of the theses proposed by the Polish logician in connection with understanding of the principle of excluded middle and logical constants occurring in this principle.