 In 1906 Łukasiewicz published a substantial piece, “Analysis and construction of the concept of cause”, which gained him his Habilitation in Lwów. It is significant both for its carefully argued method and for presaging themes that were to occupy him later. Taking concepts platonistically as abstract objects, Łukasiewicz rejects psychological, subjective and regularity accounts of causality and accepts that cause and effect are linked by necessity, which he identifies with logical necessity: “a causal relation is a necessary relation, and the relative feature […] due to which we call some object a cause, is the feature ‘entailing or bringing-about with necessity’.” The piece’s motto is Arceo psychologiam, “Reject psychology”, marking a clear break with Twardowski and Brentano, while the logical analysis is aimed at extracting the logical features of the notion of cause. It is a clear example of what later came to be called ‘analytic philosophy’, and shows Łukasiewicz bringing logical concepts to bear on scientifically central concepts, as he was later to do with his logical analysis of determinism.