German author, theatre critic, and exponent of philosophical Skepticism derived from a critique of human knowledge.

Though his novels and popular parodies of German classical poems brought him moderate literary fame, he spent most of the time between 1876 and 1905 as a theatre critic for Berliner Tageblatt. As a philosopher he was preoccupied with the implications of language. He had read Friedrich Nietzsche and Otto Ludwig's Shakespeare-Studien, and he admired Bismarck for combining a life of action with a contempt for words and ideologies. Mauthner believed that words have pragmatic social value, but, because they are applied subjectively and are ever changing, they represent sense experience only (and that imperfectly). Further, words cannot adequately express concepts, and they necessarily misrepresent reality.

Such considerations led Mauthner to philosophical Skepticism and the postulation of a criterion of truth based on personal experiences shaped by cultural influences. Mauthner applied linguistic analysis in both his major works: Wörterbuch der Philosophie, 2 vol. (1910; “Dictionary of Philosophy”), and Der Atheismus und seine Geschichte im Abendlande, 4 vol. (1921–23; “Atheism and Its History in the West”). His Skepticism was not new, but his approach to epistemology through language was unique.