Ludwig Josef Johann Wittgenstein (1889 –1951) was an Austrian philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. His writing inspired two of the twentieth century's principle philosophical movements - the Vienna Circle and Oxford ordinary language philosophy. His two chief works are considered Tractatus Logico-Philosophicus and Philosophical Investigations. Wittgenstein's influence has been felt in nearly every field of the humanities and social sciences, yet the interpretations of his thought are widely diverging.

Moritz Nähr
Ludwig Wittgenstein
Photo, ca. 1930