The article is an analysis of the metaphysical and meta-epistemological views of Stanislaw Brzozowski (1878-1911), considered to be the greatest Polish critic of the Young Poland epoch. Brzozowski’s thought exemplified the anti-positivistic turn of Polish culture, initiated in the 80’s and 90’s of the 19th century. In his works, such as Kultura i życie (Culture and Life, 1907) and Idee (Ideas, 1910), the Polish thinker refuted theories of metaphysical realism and naturalistic evolutionism, and argued that one cannot separate human thought from life as an objective, biological process. Although Brzozowski temporarily supported the meta-epistemological thesis of empiriocriticism (he claimed that truth is strictly determined by the biological factors of human nature and therefore cannot be grounded in the correspondence theory of agreement between judgments and an objective reality), in the end he took up different views connected with the transcendental idealism of Kant and Fichte. Brzozowski’s original idea was his famous philosophy of work, which claimed that an objective world does not exist because it is created by an active human subject. In other words, the Polish critic subscribed to the view that the reality is just a dynamic process. This metaphysical hypothesis was obviously opposed to realism and essentialism.