Arnold Gehlen (29 January 1904 in Leipzig, German Empire – 30 January 1976 in Hamburg, West Germany) was an influential conservative German philosopher, sociologist, and philosophical anthropologist, connected with thinkers such as Max Scheler, Helmuth Plessner. His major influences while studying philosophy were Hans Driesch, Nicolai Hartmann and especially Max Scheler.
In 1933 Gehlen signed the Vow of allegiance of the Professors of the German Universities and High-Schools to Adolf Hitler and the National Socialistic State.
He joined the Nazi Party in 1933 and had a shining career as a member of the 'Leipzig School' under Hans Freyer. He replaced Paul Tillich, who emigrated to the U.S., at the University of Frankfurt. In 1938 he accepted a teaching position at the University of Königsberg (today's Kaliningrad) and then taught at the University of Vienna in 1940 until he was drafted into the Wehrmacht in 1943. After his 'denazification' he taught at the administrative college in Speyer. He went on to teach at the Aachen University of Technology between 1962 and 1969. Gehlen became a sharp critic of the protest movements that developed in the late 1960s. Gehlen's philosophy has influenced many contemporary neoconservative German thinkers. Many terms from his work, like Reizüberflutung ("Sensory overload"), deinstitutionalization or post-history, have gained popular currency in Germany.