Kazimierz Twardowski. A Great Teacher of Great Philosophers

Kazimierz Twardowski was the founder of the Lvov-Warsaw School, one of the greatest phenomena in the European culture. The School had its representatives in all scientific disciplines, logic and mathematics including. Among his pupils are such great figures of European philosophy like: Jan Łukasiewicz, Stanisław Leśniewski, Tadeusz Kotarbiński, Władysław Tatarkiewicz and Kazimierz Ajdukiewicz. The paper presents his life and various fields of his rich activity, as well as the list of his main works and the greatest achievements in philosophy. He is best known in the world as the author of the distinction presentation-object-content, act-product, as well as the supporter of the postulate of clarity of thought and speech and the critic of psychologism, relativity of truth, symbolomania and pragmatophobia in science.