German philosopher and sociologist who considered society as an organization in which progress is determined by the power of ideas.

Barth was professor of philosophy and education in Leipzig from 1897. His Philosophy of History of Hegel and the Hegelians (1896) and his broad Philosophy of History of Sociology (1897) were outstanding works. He developed for the first time in German not only a history of the various sociological systems but also, in his critique of Hegel, the different philosophic systems of history (anthropological, political, individualist, collectivist, and ideological).

Barth edited the Quarterly of Scientific Philosophy from 1899 until 1916. His Elements of Education and Teaching Based on Psychology and Philosophy (1906; trans. into Italian, Spanish, and Russian) was concerned chiefly with moral education and was designed to replace the old textbooks based on Johann Herbart's philosophy. Barth also wrote History of Education in the Light of Sociology and History of Ideas (1911) and The Necessity of a Systematic Moral Teaching (1922).