Abstract

The philosophical ideas of ?ukasiewicz are not well known. Yet, knowledge of them is essential to understanding the inner evolution and the specific unity of the Lvov-Warsaw School. In this article, we show how, in the context of the criticism of psychologism, the young ?ukasiewicz broke away, on behalf of Aristotle, from the Brentanian and more generally from the German philosophical tradition (Husserl, Meinong). In addition, we assess the impact of this evolution on the Lvovian philosophers. The theory of acts and products (TAP), which was developed by Twardowski at that time and which asserts the autonomy of abstract notions stabilized in writing and produced in psychophysical acts, would from then on be the common epistemological basis of his disciples.