Hartmann held posts at Marburg (1922–5), Cologne (1925–31), Berlin (1931–45), and Göttingen (1945–50). His philosophy aims to establish a unified ontological system, not containing God, but with room for absolute values. Works included Ethik (1926, trs. in 3 vol., 1932); Grundzüge einer Metaphysik der Erkenntnis (1921); Das Problem des geistigen Seins (1933); Möglichkeit und Wirklichkeit (1938); Der Aufbau der realen Welt (1940); Neue Wege der Ontologie (1949, trs. New Ways of Ontology, 1952); and Ästhetik (1953).