Behler studied philosophy and literature at the universities of Mainz, Munich, Paris ( Sorbonne ) and Bonn. In 1951 he earned his doctorate at the University of Munich with Alois Dempf Dr. phil. In 1961, at the University of Bonn under Vincent Rüfner habilitation in philosophy with the work of the philosophical controversy about the eternity of the world in the 13th century. In this context, he dealt with Avicenna, Al- Ghazali, Averroes and Maimonides. He then taught as a lecturer in philosophy at the University of Bonn. In 1965 he was appointed to the University of Washington. In 1976 he was Chairman of the Department of Comparative Literature at the University of Washington in Seattle.
His research included Friedrich von Schlegel and the early Romantic period. He was founder and editor of Critical Friedrich Schlegel output. His book Friedrich Schlegel in autobiographies and image documents is published in its seventh edition, 2007. Also known are his two books about the irony: Classical irony, romantic irony, tragic irony, and irony and literary modernism. His wife Diana Behler, a student of Raymond Always True, was also Professor of German Studies and Comparative Literature. His son Constantin is Professor at the University in Bothell. Behler was a friend of Jakob Baxa and Jean Grondin.
- Classical irony, romantic irony, tragic irony: the origin of these terms, University Press, ISBN 3-534-05741-4 Darmstadt 1981
- Irony and literary modernism, Schöningh, Paderborn; Munich; Vienna; Zurich 1997 ISBN 3-506-70714-0