The volume is a collection of essays about prominent Polish 20th century philosophers of science and scientists who were concerned with problems in the philosophy of science. The contribution made by Polish logicians, especially those from the Lvov-Warsaw School, like Łukasiewicz, Kotarbiński, Czeżowski or Ajdukiewicz, is already well known. One of the aims of the volume is to offer a broader perspective. The papers collected here are devoted to the work of such philosophers as Zawirski, Metallmann, Dąmbska, Mehlberg, Szaniawski and Giedymin as well as to the work of such scientists as Smoluchowski, Fleck, Infeld and Chyliński. The introduction to the volume, written by the editor and Jacek Jadacki, presents an overview of the history of the Polish philosophy of science from the foundation of the Cracow Academy (in 1364) to the present.