John O'Callaghan is associate professor of Philosophy and Director of the Jacques Maritain Center at the University of Notre Dame. He has written or edited a number of books and articles in the area of Thomistic studies, including Thomist Realism and the Linguistic Turn (2003), and Recovering Nature (with Thomas Hibbs, 1999). He is a past president of the American Catholic Philosophical Association, and is a permanent member of the Pontifical Academy of St. Thomas Aquinas.
Aquinas's argument is not that killing an offender is always lawful, much less that it is mandatory. It is lawful upon a condition, namely, that it is necessary to protect the common good from a threat. Absent that condition, Aquinas does not argue or even suggest that killing a malefactor, including one who has committed murder, is lawful.
Date posted: 2023-03-25