Kazimierz Twardowski had a twofold role in the recent history of philosophy. He had a decisive influence on Polish philosophy in the twentieth century; and at the turn of the twentieth century he contributed to the transformation of European philosophy in its search for new, intellectually responsible methods of philosophical inquiry. His conception of philosophy and his specific contributions to epistemology, philosophical psychology, and theory of science helped to pave the way for the emergence of phenomenology and of some forms of analytic philosophy.

Twardowski was born in Vienna. He studied philosophy at the University of Vienna, where he came under the influence of Franz Brentano. In 1892 he received a PhD degree from the university, and he became a lecturer there in 1894. In 1895 he was appointed to a chair of philosophy at the University of Lwów, where he taught until 1930.

Like Brentano, he...