I work on ancient philosophy and the history of ancient science, in particular on Aristotle's theory of argumentation and its epistemic underpinnings. I have also published on the history of ancient astronomy, the history of the historiography of ancient philosophy, and on the theory of our knowledge of the past and the interpretation of the texts and testimony which provide the basis for it. I am based at the Humboldt-Universit├Ąt zu Berlin, where I am regular teaching member of the philosophy faculty and co-odinator of the August Boeckh Centre for Classical Studies.