Medieval history; ancient and medieval political thought.
History of Western Civilization I
History of Western Civilization II
Civilization of the Middle Ages I
Civilization of the Middle Ages II
Ph.D., Johns Hopkins, 1969.
Augustine, especially relations between his theology and political thought.
Early Christian thought.
Medieval Roman and Canon law.
Ancient, medieval, and early modern political theory.
Crusades and Warfare.
The Just War in the Middle Ages (Cambridge, Cambridge University Press, 1975). (Awarded the Herbert Baxter Adams Prize of the American Historical Association, 1976). Second, revised, printing and paperback edition, 1977. Digital Reprint, 2003.
Articles, Chapters In Books [all refereed]:
"Innocent IV's Proposals to Limit Warfare," in Proceedings of the Fourth International Congress of Medieval Canon Law; Monumenta Iuris Canonici, Series C, vol. 5 (Città del Vaticano, Biblioteca Apostolica Vaticana, 1976), 383-399.
"Paulus Vladimiri's Attack on the Just War: A Case Study in Legal Polemics," in Brian Tierney and Peter Linehan, eds., Authority and Power. Studies on Medieval Law and Government presented to Walter Ullmann (Cambridge, Cambridge University Press, 1980), pp. 237-254.
"The Historical Perspective of the Bishops' Pastoral Letter: The View of One Medievalist," in Charles. J. Reid, Jr., ed., Peace in a Nuclear Age. The Bishops" Pastoral Letter in Perspective (Washington, Catholic University of America Press, 1986), pp. 86-97.
"Love and Hate in Warfare: The Contribution of Saint Augustine," Nottingham Medieval Studies 31 (1987), 108-124. Reprinted: J. M. Dunn and Ian Harris, eds., Great Political Thinkers Section 1 (Cheltenham (UK), Edward Elgar. forthcoming).
"'Only Something Good Can Be Evil': The Genesis of Augustine's Secular Ambivalence," Theological Studies 51 (1990), 698-716.
"The Bifurcation of Creation: Augustine's Attitudes Toward Nature," Sewanee Mediaeval Studies no.6 (Susan J. Ridyard and Robert G. Benson, eds., Man and Nature in the Middle Ages) (1995), 83-96.
"Augustine: Conversion by the Book," in James Muldoon, ed., Varieties of Religious Conversion in the Middle Ages (Gainesville, FL, University Press of Florida, 1997), pp. 13-30.
"Persuading the Donatists: Augustine's Coercion by Words," in William E. Klingshirn and Mark Vessey, eds., The Limits of Ancient Christianity. Essays on Late Antique Thought and Culture in Honor of R. A. Markus (Ann Arbor, MI, University of Michigan Press, 1999) pp. 115-130.
"Augustine and Gratian on Religious Coercion: 'Augustinus non tamen legum severitatem non observandam docuit'," in Proceedings of the Tenth International Congress of Medieval Canon Law; Monumenta Iuris Canonici, Series C, vol. 11 (2001) (Città del Vaticano, Biblioteca Apostolica Vaticana), 861-873.
“La conversión de Agustín: de la espada a la palabra,” Augustinus 48 (2003) 229-235 (= Spanish translation of 1999 Oxford Patristics Conference paper).
“Miles”, submitted to Augustinus Lexikon, July 2008.
“Just War”, in Robert Pasnau, ed., Cambridge History of Medieval Philosophy (2 vols., Cambridge, 2010), II, ch. 43, 593-606.