Just war

Just war theory (Latin: jus bellum iustum) is a doctrine, also referred to as a tradition, of military ethics studied by theologians, ethicists, policy makers, and military leaders. The purpose of the doctrine is to ensure war is morally justifiable through a series of criteria, all of which must be met for a war to be considered just. The criteria are split into two groups: "right to go to war" (jus ad bellum) and "right conduct in war" (jus in bello). The first concerns the morality of going to war, and the second the moral conduct within war. Recently there have been calls for the inclusion of a third category of Just War theory—jus post bellum—dealing with the morality of post-war settlement and reconstruction.

Just War theory postulates that war, while terrible, is not always the worst option. Important responsibilities, undesirable outcomes, or preventable atrocities may justify war.

Opponents of Just War theory claim that there has never been a political philosopher who argued that war poses any real benefit to any participating party. In a large number of cases, philosophers state that individuals need not be of guilty conscience if required to fight. A few nobilify the virtues of the soldier while declaring spite for war itself. A few, such as Rousseau, argue for insurrection against oppressive rule.

The historical aspect, or the "just war tradition," deals with the historical body of rules or agreements that have applied in various wars across the ages. The just war tradition also considers the writings of various philosophers and lawyers through history, and examines both their philosophical visions of war's ethical limits and whether their thoughts have contributed to the body of conventions that have evolved to guide war and warfare.

The Indian epic, the Mahabharata, offers one of the first written discussions of a "just war." In it, one of five ruling brothers asks if the suffering caused by war can ever be justified, and then a long discussion ensues between the siblings, establishing criteria like proportionality (chariots cannot attack cavalry, only other chariots; no attacking people in distress), just means (no poisoned or barbed arrows), just cause (no attacking out of rage), and fair treatment of captives and the wounded. The war in the Mahabharata is preceded by context that develops the "just cause" for the war including last minute efforts to reconcile differences to avoid war. At the beginning of the war, there is the discussion of "just conduct" appropriate to the context of war. In ancient Rome, a "just cause" for war might include the necessity of repelling an invasion, or retaliation for pillaging or a breach of treaty. War was always potentially nefas, ("wrong, forbidden") and risked religious pollution and divine disfavor. A just war (bellum iustum) thus required a ritualized declaration by the fetial priests. More broadly, conventions of war and treaty-making were part of the ius gentium, the "law of nations," the customary moral obligations regarded as innate and universal to human beings. The quintessential explanation of Just War theory in the ancient world is found in Cicero's De Officiis, Book 1, sections 1.11.33–1.13.41

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