The Origin of Just War Theory

November 14, 2012

The Underworld, Walter Bayes, 1918

From The New York Times:

The origin of just war theory is usually traced to the writings of Augustine, though many of the theory’s elements became well established only much later, during its “classical” period between the early 16^thand mid-17^th centuries. The principles of just war theory were then understood to be part of a unified set of objective moral principles governing all areas of life. Like the principles concerned with truth-telling, commerce, sexual relations, and so on, just war principles were to be used in guiding and judging the acts of individuals. Later, however, as individuals became more firmly sorted into sovereign states and the regulation of warfare through treaties between states became increasingly effective, the theory began to conceive of war as an activity of states, in which individual soldiers were merely the instruments through which states acted.

Beginning in earnest in the 17^th century and continuing through the 20^th, the theory of the just war evolved in conjunction with international law. While the theory initially guided the development of the law, by the 19^th century and especially over the course of the 20^th, the law had acquired such great practical importance that the most significant developments in normative thought about war were pioneered by legal theorists, with just war theorists trailing humbly along behind.

During the aftermath of World War II, a consensus began to emerge that a set of just war principles, which coincided closely with the law as codified in the United Nations Charter and the Geneva Conventions, provided the correct account of the morality of war.

Both just war theory and the law distinguished between the justification for the resort to war (jus ad bellum) and justified conduct in war (jus in bello). In most presentations of the theory of the just war there are six principles of jus ad bellum, each with its own label: just cause, legitimate authority, right intention, necessity or last resort, proportionality and reasonable hope of success. Jus in bello comprises three principles: discrimination, necessity or minimal force, and, again, proportionality. These principles articulate in a compressed form an understanding of the morality of war that is, in its fundamental structure, much the same as it was 300 years ago. Mainly as a result of its evolution in tandem with a body of law that has states rather than individual persons as its subjects, the theory in its present form is quite different from the classical theory from which it is descended. To distinguish it from its classical predecessor, some just war theorists refer to it as the traditional theory of the just war, though for brevity I will generally refer to it simply as “the Theory.”