Austrian philosopher remembered for his introduction of the term Gestalt (Gestalt psychology) (“figure”) into psychology and for his contribution to value theory.

As a student at the University of Vienna, Ehrenfels came under the influence of Franz Brentano and Alexius Meinong. Ehrenfels, who was licensed to teach at Vienna in 1888, moved to Prague in 1896 as extraordinary professor of philosophy at the German university there and served as ordinary professor (1900–29).

Ehrenfels' article “Über Gestaltqualitäten,” which appeared in the Vierteljahrsschrift für wissenschaftliche Philosophie, xiv (1890; “Quarterly Journal for Scientific Philosophy”), was the starting point of Gestalt psychology. He used the term Gestalt to refer to the complex data that require more than immediate sense experience in order to be perceived. For example, an immediate sense experience of sound is insufficient to signify a melody to the hearer. Recollection and sometimes other components are also necessary for apprehension. All the components taken together form a Gestalt, or whole structure. He extended the same principle to logic and number theory.

In his System der Werttheorie, 2 vol. (1897–98; “System of Value Theory”), also a pioneer work, Ehrenfels treated the concept of value psychologically, as a function of desire. The value placed by persons on various objects thus became the basis of both his social and his individual ethics. Ehrenfels' other writings include plays, choral dramas, two pamphlets on the composer Richard Wagner (1896 and 1913), Grundbegriffe der Ethik (1907; “Foundations of Ethics”), Sexualethik (1907; “Sexual Ethics”), Kosmogonie (1916), and Die Religion der Zukunft (1929; “The Religion of the Future”).