John Duffy is a native of Ireland who studied Classics at Maynooth College and at University College Dublin. He did his doctoral work in the Classics Department at S.U.N.Y. Buffalo under the guidance of L. G. Westerink.
The main focus of his research has been on Byzantine literature in the areas of theology, philosophy, medicine, and religious tales. One of his specialties is the preparation of text editions, a type of research he believes to be of fundamental importance for Medieval Greek which, in the matter of reliable texts, lags far behind not only Classics but Medieval Latin as well.
Among his publications are Synodicon Vetus, ed. and trans. with J. Parker (Dumbarton Oaks Texts, 1979); Stephanus the Philosopher, A Commentary on the Prognosticon of Hippocrates (Corpus Medicorum Graecorum, Berlin, 1983); Gonimos: Neoplatonic and Byzantine Studies Presented to Leendert G. Westerink at 75, ed. with J. Peradotto (Buffalo, 1988); Michael Psellos, Philosophica Minora I (Bibliotheca Teubneriana, Stuttgart/Leipzig, 1992); John of Alexandria, Commentary on Hippocrates' Epidemics VI, (Corpus Medicorum Graecorum, Berlin 1997); Michael Psellos, Theologica II, ed. with L. G. Westerink (Bibliotheca Teubneriana, Munich/Leipzig, 2002); Nicetas David, The Life of Patriarch Ignatius, text and tr. by A. Smithies, with notes by J. M. Duffy, Dumbarton Oaks Texts XIII, (Washington DC, 2013); Sophronius of Jerusalem, Homilies, ed. and tr. by J. M. Duffy, Harvard U. Press (Cambridge MA, 2020).
Projects underway include a critical edition and English translation, in collaboration with K. Ierodiakonou, of Michael Psellos’ Commentary on the De interpretatione of Aristotle, and the editio princeps and English translation, in collaboration with Alexander Alexakis, of two treatises in defence of icon veneration by Sophronios of Alexandria. He is also preparing the first edition of the glosses and scholia on the Heavenly Ladder of John Climacus preserved in a 10th cent. Sinai manuscript.
Professor Duffy has been a Junior Fellow at Dumbarton Oaks (1971–73) and a Senior Fellow (1991–2023); he was an Alexander von Humboldt Fellow at the Freie Universität Berlin (1984; 1987). He was also a member of the following: the Kommission für das Corpus Fontium Historiae Byzantinae (2001–2023), the U.S. National Committee for Byzantine Studies (1992–2002), the Editorial Board of Dumbarton Oaks Papers (1996–2023). From 2005 to 2023 he was the editor of the Washington series of the Corpus Fontium Historiae Byzantinae. Since 2012 he has served on the Editorial Board of the Dumbarton Oaks Medieval Library (Byzantine Greek Series). In 1999 he was the recipient of the Paideia Award from the Greek Archdiocese of America.