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Frans de Haas

Professor of Ancient and Medieval Philosophy

Prof.dr. F.A.J. de Haas
+31 71 527 2010

Frans de Haas is a Professor of Ancient and Medieval Philosophy / Director Dutch Research School of Philosophy at the Institute of Philosophy.

More information about Frans de Haas


My teaching is mainly concerned with influential aspects of the philosophy of Antiquity and the Middle Ages. I am interested in the reception of Plato, Aristotle, Stoics and Sceptics in the philosophical commentary tradition of late Antiquity (200-600 CE) and beyond. Philosophers in Late Antiquity discuss critical questions and problems which have shaped the reception of ancient philosophy in the Middle Ages, the Renaissance and the Early Modern period. Sometimes they have even managed to dominate modern interpretations of Plato and Aristotle.


My current research focuses on Alexander of Aphrodisias (ca. 200 CE), who was the most influential interpreter of Aristotle in Late Antiquity. While occupying the chair in Aristotelian philosophy in Athens set up by the Roman emperor Marcus Aurelius in 176 CE, Alexander re-designed Aristotelianism in order to offer the best possible alternative to the Platonic, Stoic and Epicurean philosophies of his peers in Athens. The purpose of my research is to show how his famous adaptations of Aristotelian philosophy in e.g. the fields of logic, metaphysics, hylomorphism, psychology and freedom of action combine to make a new consistent Aristotelianism for the third century CE. It was this Aristotelianism that shaped Neoplatonism,  as well as Medieval and Renaissance Aristotelianisms.

General interests that I have pursued throughout my career include Aristotle's philosophy of mind and philosophy of science, and their reception in later Antiquity. In addition, I am fascinated by the interplay between philosophy and the exact sciences like mathematics, astronomy and music in Antiquity. 

More recently, I have developed an interest in the role of ancient western philosophy in intercultural philosophical debates, and the need to rewrite the history of ancient philosophy as an open-minded, rather than as a geographically and culturally closed, human endeavour. I am currently exploring the systematic and historical connections between innovations in Hellenistic philosophy and Asian philosophy, e.g. Scepticism and Buddhist philosophy.

I currently lead a research group with 8 PhD candidates in ancient philosophy working on projects involving Plato, Aristotle, Alexander of Aphrodisias, and Iamblichus. The group has been regularly expanded with visiting PhD candidates and postdocs from e.g. Brazil, China, and Denmark. In 2020-2022 Marie-Curie Fellow Sebastian Mateiescu (Romania) joins the group with his research on the relations between Neoplatonic commentaries on the Categories and the logical innovations in post-Chalcedonian Christian theology of the 5-7th centuries CE.

International cooperation

• The Chairs in Ancient Philosophy of Leiden, Utrecht and Leuven cooperate in the Centre for Ancient Philosophy (CAW in Dutch), which facilitates part of the training of Research MA and PhD students, and organizes regular meetings, lectures by invited speakers etc.
•    Member and former president of the Academia Platonica septima Monasteriensis, a European network for research in Platonism, established in Münster (Germany).
•    Team leader in the European programme From natural philosophy to science (2002-2007) funded by the European Science Foundation.
•    Since 2012 I have established and developed cooperation with the School of Philosophy of Beijing Normal University (China), where I held a guest professorship at the Center for the Study of Sciences and Humanities in 2012-2015, and continue to teach regularly. I am also regularly invited as a speaker by other universities in China, including Peking University, Renmin University, and the China University for Politics and Law.
•    Since 2003 I have been a member of the editorial board of the book series Philosophia Antiqua edited by Brill Publishers, since 2019 as editor-in-chief.

Curriculum vitae

Prof.dr. Frans A.J. de Haas (1963) studied Classics, and received his PhD in ancient philosophy from Leiden University (1995). He spent a year as a visiting research fellow at the Institute of Classical Studies (London) on a scholarship from the Niels Stensen Foundation. He was Research Fellow of the Dutch Royal Academy of Arts and Sciences at Utrecht University (1997-2000), and Assistant Professor of Ancient and Medieval Philosophy at Nijmegen University (2000-2002). Since 2003 he is Full Professor of Ancient and Medieval Philosophy at Leiden University. 

In the years 2004-2005 he was Dean of the (then) Faculty of Philosophy, in 2011-2017 Academic Director of the Institute for Philosophy. Since 2019 he leads the Leiden Centre for Late Antique and Medieval Studies (LAMS) established by Dr Bdaiwi, in cooperation with Dr Van den Berg. In 2019-2023 he is Director of the Dutch Research School in Philosophy (OZSW).

Professor of Ancient and Medieval Philosophy

  • Faculty of Humanities
  • Instituut voor Wijsbegeerte

Work address

P.J. Veth
Nonnensteeg 1-3
2311 VJ Leiden
Room number 2.18



  • Faculty of Humanities
  • Centre for the Arts in Society
  • Griekse T&C

Work address

Arsenaalstraat 1
2311 CT Leiden
Room number B2.01




  • No relevant ancillary activities
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