The aim of this paper is to present life, main works and ideas of Tadeusz Czeżowski, who was a Polish logician, philosopher and an eminent representative of the Lvov-Warsaw School. Czeżowski's contribution to the contemporary philosophy and logic is of universal value and includes such achievements as the classification of reasoning types, the analysis of singular propositions, the analysis of Aristotle's modal logic from the point of view of modern logic, the reconstruction of Brentano's syllogistic and the theory of transcendental concepts.