Born Nov. 19, 1843; died Aug. 18, 1896. Swiss idealist philosopher, one of the founders of empiriocriticism; a professor at the University of Zurich.

The basic concept of Avenarius’ philosophy is experience, in which he tries to dissolve the opposition between matter and mind—the physical and the psychological (A Critique of Pure Experience, 1888–90; Russian translation 1905, 1907–08). Yet the concept of the physical and psychological only as the content of both external and internal experience is an admission of the primacy of consciousness, for experience without a subject—that is, without consciousness—is impossible. Avenarius’ doctrine of “principal coordination”—“without the subject there is no object and without the object there is no subject”—is subjective idealism excluding objective reality which exists independent of consciousness. To objective truth, Avenarius juxtaposed the biological value of knowledge and thought according to the “principle of the least expenditure of energy.” The philosophy of Avenarius and his students— R. Willy, I. Petztoldt, F. Carstanjen—was subjected to extensive criticism by V. I. Lenin in his work Materialism and Empiriocriticism (1908, published 1909).