Just War Doctrine
The ‘just war’ doctrine, in history and political science, attempts to define moral criteria for the initiation of war (jus ad bellum: Latin, ‘justice prior to war’) and the conduct of war (jus in bello: Latin, ‘justice during war’). Attempts to develop just war criteria can be traced to classical Roman law, itself influenced by Greek and Hebrew philosophy. These ideas were systematized in European, Christian canon law (see Catholic political thought) in the early Middle Ages, and then developed further in the 16th and 17th centuries by jurists like Grotius. Key figures in the elaboration of criteria for a just war include St. Augustine in the 5th century, Thomas Aquinas in the 13th century, and Reinhold Niebuhr in the 20th.