just war

Just war is a concept closely associated with Christian thinking regarding the resort to and conduct of war, but all the world's major religions have addressed the issues associated with warfare and have contributed to the development of notions of restraint and discrimination. The modern concept of just war draws not only upon these religious traditions, but also upon more recent approaches to the question of the laws of war. In the 19th and 20th centuries, thinking about the morality of war became as much a problem for secular ethicists, international lawyers, and advocates of universal human rights as for religious thinkers.

Early Christians were fundamentally pacifist. Accepting no distinction between murder and killing in war, they were convinced that any killing—even in self-defence in war—was wrong. A fundamental shift began when Constantine converted to Christianity and then, in 313, made the Roman a Christian empire in the Edict of Milan. As the ‘official’ religion of a martial empire, Christianity began to move away from the seeming unworldliness of absolute pacifism and began to wrestle with the possibility that war might, in certain circumstances, be both politically necessary and morally justifiable. The idea of fighting a ‘Christian war’ took several centuries to develop, and it was not until the end of the Dark Ages that the first indications of just-war thinking began to emerge. Relatively quickly thereafter, the two strands of just-war thinking began to emerge: jus ad bellum, concerning the resort to war, and jus in bello, concerning conduct in war.

Drawing upon the work of St Augustine and particularly St Thomas Aquinas in the 13th century, the concept of jus ad bellum has been elaborated over the centuries and requires that several conditions be met before resorting to war. First, there must be a just cause or right intention. That is, the purpose of the war must be to right a wrong which has been committed (self-defence against unlawful aggression would be considered just), and the ultimate objective must be peace. Second, the use of armed force must always be considered a last resort. Third, the resort to war is the preserve of legitimate authority; an arbitrary act of an individual cannot be considered just. Fourth, there must be good prospects; no matter what the grievance, if war is likely to be a wasted effort, it should not be undertaken. And finally, there should always be a sense of proportion between means and ends, in that the good to be achieved through war must outweigh the damage and harm to be endured.

Jus in bello thinking concentrates primarily on the effect of the conflict and is expressed in two different approaches to the regulation of armed conflict (see Geneva and Hague Conventions). The Hague approach concerns hostilities in general, the conduct of combat, and the concepts of occupation and neutrality while the Geneva approach addresses the protection and humane treatment of POWs, those made hors de combat through wounding or otherwise, and the status of non-combatant civilians and medical personnel. Jus in bello in its evolved form thus presents two key principles. First, conduct should be proportionate and belligerents cannot assume unlimited rights to injure an opponent. Second, there must be discrimination between combatants and others.

In early 1999 NATO's bombardment of Serbia on behalf of Kosovar Albanians was frequently debated in just-war terms. As so often in the past the concept was not able to produce an unequivocal and universally agreed judgement on NATO's action. There are indeed many criticisms to be made of the just war, on moral, legal, and political grounds. But perhaps the most eloquent critique was that offered by the British historian A. J. P. Taylor: ‘Bismarck fought “necessary” wars and killed thousands, the idealists of the 20th century fight “just” wars and kill millions.’

— Paul Cornish

An armed conflict in which one side enjoys the sanction of moral, religious, and legal tradition with respect to the initiation of the conflict, its conduct, and the objectives sought.

See the Introduction, Abbreviations and Pronunciation for further details.

A war held to be justly caused and humanely conducted.

Classical Greek thought, as represented most graphically in Thucydides' History of the Peloponnesian War, accepted war as an inherent aspect of politics. The early Christians were pacifist and practised abstention from politics. The Roman empire, once converted to Christianity, had to reconcile the pacifist teaching of Christ with the demands of politics, power, and war. Augustine's City of God argued that day-to-day acceptance of political ‘realities’ was inevitable for Christians living in a fallen world. The theme was developed by Aquinas, who distinguished between just and unjust war using two sets of criteria, the justice of the cause (jus ad bellum) and the justice of the conduct ( jus in bello).

The two elements of just cause and just conduct have continued to dominate the debate. In the twentieth century, just cause has narrowed to self-defence against aggression and helping the victims of aggression. The doctrine of just cause has concentrated on discrimination between combatants and non-combatants and proportionality between the injustice suffered and the level of retaliation. The waging of ‘total war’ has strained practically to breaking point the doctrine of just war.

Nuclear deterrence has added an additional dimension to the debate because, while most theorists of just war have condemned nuclear war as unjust (on grounds of discrimination and proportionality, but also on grounds that there is no prospect of a successful outcome), some Christian thinkers have considered deterrence—the threat to use nuclear weapons—to be morally allowable. Some Catholics, for instance the American Bishops, have distinguished between the mere possession of nuclear weapons, constituting a so-called existential deterrent, and the intention to use those weapons, the former being allowable while the latter is disallowed. See also Suarez.

— Peter Byrd