 Bolzano, Bernard |  Brentano, Franz |  Brentano, Franz: theory of judgement |  Husserl, Edmund |  Ingarden, Roman |  intentionality |  Leśniewski, Stanisław |  Lvov-Warsaw School |  Meinong, Alexius |  mereology |  nonexistent objects |  psychologism |  Wundt, Wilhelm Maximilian 