This collection celebrates the centenary of the Lvov - Warsaw school, established by Kazimierz Twardowski in Lvov in 1895. This school belongs to analytic philosophy and successfully worked in all branches of philosophy. The Warsaw school of logic became perhaps the most important part of Twardowski's heritage. Lesniewski, Lukasiewicz and Tarski, leading Polish logicians, achieved results which essentially influenced the development of contemporary logic. A close connection of logic and philosophy was a typical feature of the Lvov - Warsaw school. The papers included in the collection deal with all directions of research undertaken by Polish analytic philosophers. Special attention is paid to logic and comparisons with other philosophical movements, particularly with Brentanism, which was one of the sources of the Lvov - Warsaw school.