The Modern Secularization of Just War Theory and its Lessons for Contemporary Thought

Just war theory is a family of views that has undergone many important changes throughout its development in the Western philosophical tradition. The following is an historical analysis of the transition from a religious to a secular conception of just war theory in the Early Modern period. My main argument is that the secularization of the theory led to the separation of jus ad bellum from jus in bello, a major change that had positive consequences on the theory and its application. One important consequence of this change was to place combatants on both sides of a conflict on an equal moral footing, applying the principles of jus in bello equally to all. But the progress made since the theory’s secularization is threatened to be reversed. Michael Walzer’s “supreme emergency” exemption allows jus in bello to be sacrificed under certain extreme conditions, and Jeff McMahan promotes the view that just and unjust combatants do not have the same rights in war. Furthermore, a popular idea in the social sciences is that if the nations of the world all adopted a democratic mode of governance there would be few to no wars. This democratic peace theory, while not explicitly condoning the use of violence to achieve the result of a lasting peace, has had profound policy implications among democratic states. The United States, for example, has used the justification of spreading democracy abroad to promote its military ambitions for the last century. I put forward a number of arguments against these views and instead promote the adoption of a Kantian program for gradually moving towards a more peaceful international realm based on mutual trust and cooperation. Religious justifications for going to war are no longer popular as a lasting peace was not achieved but rather contradicted by the massive violence caused by religious wars. If the religious justifications for going to war put forward in the Middle Ages were fallacious then I believe we should be skeptical of similar arguments put forward today in the name of political structure