Nicolai Hartmann
Paul Nicolai Hartmann (; 20 February 1882 – 9 October 1950) was a Baltic German philosopher. He is regarded as a key representative of critical realism and as one of the most important twentieth-century metaphysicians. Biography Hartmann was born a Baltic German in Riga, which was then the capital of the Governorate of Livonia in the Russian Empire, and which is now in Latvia. He was the son of the engineer Carl August Hartmann and his wife Helene, born Hackmann. He attended from 1897 the German-language high school in Saint Petersburg. In the years 1902–1903 he studied Medicine at the University of Yuryev (now Tartu), and 1903–1905 classical philology and philosophy at the Saint Petersburg Imperial University with his friend Vasily Sesemann. In 1905 he went to the University of Marburg, where he studied with the neo-Kantians Hermann Cohen and Paul Natorp. In Marburg began a lifelong friendship with Heinz Heimsoeth. In 1907 he received his doctorate with the thesis Das Seinsproblem in der griechischen Philosophie vor Plato (The Problem of Being in Greek Philosophy Before Plato). In 1909 he published the book Platos Logik des Seins (The Logic of Being in Plato). The same year he completed his habilitation on Proclus: Des Proklus Diadochus philosophische Anfangsgründe der Mathematik (Proclus Diadochus' Philosophical Elements of Mathematics). In 1911, Hartmann married Alice Stepanitz, with whom he had a daughter, Dagmar, in 1912. In 1912 he published Die philosophischen Grundfragen der Biologie (The Philosophical Foundations of Biology). From 1914 to 1918 he did military service as an interpreter, letter censor, and intelligence officer. In 1919, i.e., after the war, he received a position as Privatdozent in Marburg. Around this time he met Martin Heidegger. In 1920 he became Associate Professor (außerordentlicher Professor) and in 1921 appeared the work that established him as an independent philosophical thinker, Grundzüge einer Metaphysik der Erkenntnis (Foundation of a Metaphysics of Knowledge). The following year he became Full Professor (ordentlicher Professor) as successor of the Chair held by Natorp. In 1925, he moved to Cologne, where he came into contact with Max Scheler. In 1926 he published his second major work—Ethik—in which he develops a material value ethics akin to that of Scheler. The same year he divorced from his wife. In 1929 Hartmann married Frida Rosenfeld, with whom he had a son, Olaf (1930), and a daughter, Lise (1932). In 1931 he became Professor of Theoretical Philosophy in Berlin. He held the Chair until 1945. During this time he successively published many pieces of his ontology: Das Problem des geistigen Seins (The Problem of Spiritual Being) (1933), Zur Grundlegung der Ontologie (On the Foundation of Ontology) (1935), Möglichkeit und Wirklichkeit (Possibility and Actuality) (1938) and Der Aufbau der realen Welt. Grundriß der allgemeinen Kategorienlehre (The Structure of the Real World. Outline of the General Theory of Categories) (1940). The unrest of the National Socialist period seems to have left Hartmann relatively undisturbed in his task of developing a new ontology. In the "'-Dossiers über Philosophie-Professoren" (i.e. SD-files