Teichmüller Gustav (1832–88), German philosopher who contributed to the history of philosophy and developed a theory of knowledge and a metaphysical conception based on these historical studies. Born in Braunschweig, he taught at Göttingen and Basel and was influenced by Lotze and Leibniz. His major works are Aristotelische Forschungen (Aristotelian Investigations, 1867–73) and Die wirkliche und scheinbar Welt (The Actual and the Apparent World, 1882). His other works are Ueber die Unsterblichkeit der Seele (1874), Studien zur Geschichte der Begriffe (1874), Darwinismus und Philosophie (1877), Ueber das Wesen der Liebe (1879), Religionsphilosophie (1886), and the posthumously published Neue Grundlegung der Psychologie und Logik (1889). Teichmüller maintained that the self of immediate experience, the ‘I,’ is the most fundamental reality and that the conceptual world is a projection of its constituting activity. On the basis of his studies in the history of metaphysics and his sympathies with Leibniz’s monadology, he held that each metaphysical system contained partial truths and construed each metaphysical standpoint as a perspective on a complex reality. Thinking of both metaphysical interpretations of reality and the subjectivity of individual immediate experience, Teichmüller christened his own philosophical position ‘perspectivism.’ His work influenced later European thought through its impact on the philosophical reflections of Nietzsche, who was probably influenced by him in the development of his perspectival theory of knowledge. See also LEIBNIZ, LOTZE. G.J.S.