ABSTRACT
Contemporary moral reflection on armed force is heavily indebted to the pioneering work of medieval theorists: canon lawyers such as Gratian and Innocent IV, as well as theologians such as Alexander of Hales and Thomas Aquinas. This chapter traces out their thought on ethical decision-making about war. They emphasized how leaders who were entrusted with oversight of the common good (the possessors of legitimate authority) could rightly resort to armed force only to rectify an egregious wrong (just cause) and under condition that their ultimate aim was to promote the well-being of the political community (right intention). Since the common good was conceived of in moral terms-the collective life of virtue-those who led their polities to war were expected to be virtuous themselves. Thomas Aquinas, in particular, emphasized how the initiation of war should flow from a choice which, on the part of the leader, is inwardly regulated by the appropriate virtues. By the same token, the obedience which is due to these leaders on the part of the citizenry must likewise be tempered by virtue.
