Ludwig Josef Johann (ˈluːtvɪç ˈjoːzɛf joˈhan). 1889–1951, British philosopher, born in Austria. After studying with Bertrand Russell, he wrote the Tractatus Logico-Philosophicus (1921), which explores the relationship of language to the world. He was a major influence on logical positivism but later repudiated this, and in Philosophical Investigations (1953) he argues that philosophical problems arise from insufficient attention to the variety of natural language use