is an art historian and the head of the Interdisciplinary Center »Art and Esthetics« at Freie Universität Berlin. His research focus is on French art of the 19thand early 20thcentury, US-American art of the post-1945 era and on modern aesthetics. He is also head of the subordinated project of »Mittelbarkeit und Unmittelbarkeit in der Kunst der Moderne« as part of a collaborate research project funded by the »Deutsche Forschungsgemeinschaft« (DFG) on »Ästhetische Erfahrung im Zeichen der Entgrenzung der Künste«, a project he also supervises.
had been a member of the Collaborate Research Centre »Ästhetische Erfahrung im Zeichen der Entgrenzung der Künste« and professor of Ethics and Aesthetics at Potsdam University until 2008. He has since moved on to teach at the professorship of Practical Philosophy as part of the Cluster of Excellence »Die Herausbildung normativer Ordnungen« and at the department of Philosophy at Frankfurt Main University. His research focus is on Political Philosophy (freedom and normativity, democracy and equality), Legal Theory (human rights, subjective justice), Aesthetics (the tragedy and theatre) and the Theory of Subjectivity (spirit and nature, ability and activity). He is a member of the editorial board of numerous magazines (Constellations: An International Journal of Critical and Democratic Theory; Philosophy and Social Criticism; Revue d’Esthétique; Polar). Together with Dieter Thomä he is editor of the Deutsche Zeitschrift für Philosophie with book reviews on philosophical literature.