Thomas Aquinas (1224/5–1274)

The fact that Thomas Aquinas speaks of "public authority" to declare war, as an equivalent for the more traditional term of "princely authority", shows to what degree he had moved beyond the confines of medieval feudalism that was oriented around personal bonds of fealty to one&s;s lord. In reflecting on just war Aquinas was visibly dependent on St. Augustine and Gratian. Aquinas was also well versed in the writings of his confrere Raymond of Penafort, an influential canon lawyer who had considered how soldierly participation in war should be taken up in the confessional. That princes alone should occupy the office of supreme command, "calling the multitude to action as happens in wars", Aquinas deduces from their principal duty, which is "to care for the polity". By framing the public use of force in terms of protection, Aquinas launched a new concept into just-war reflection, namely that of defensive war .