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Written as the first chapter of War on Iraq - A Just War? by Bruce Duncan CSsR this chapter was omitted because of lack of space. However, this short history sketches some background to debates on the morality of war.

Armed conflict and warfare have long been painful aspects of human existence, and over thousands of years people developed customs and expectations concerning fighting. In the western tradition, various elements of what came to be called `just war? theory gradually emerged, identifying key moral conditions which determined if a war was justified, and later, moral criteria for how wars should be fought. These principles or criteria of just war were far from self-evident, but resulted from the distilled reflections on the long, agonising experience of often endemic warfare. Roman law and military custom set the foundations for the western tradition.1  But how could this be reconciled with the Christian message of peace and non-violence?

'Peace be with you'

The Gospels present Jesus as being generally opposed to violence and encouraging peacemaking, but do not clearly address the question of war fighting. In contrast with the tribalism of the Middle East and even with Jewish history, Jesus' God is not a warrior god fighting against the enemies of the Jews. Jesus is depicted as having nothing to do with the holy war tradition of ancient Israel, and distancing himself from the militant millennialism of his day.

Not only is killing forbidden, but Jesus insists that 'Anyone who nurses anger against his brother must be brought to justice' (Mt. 5:21-22). And instead of the tribal code of 'lex talionis' or eye for an eye, Jesus declares: 'But what I tell you is this: Do not resist those who wrong you. If anyone slaps you on the right cheek, turn and offer him the other also'. 'Love your enemies and pray for your persecutors; only so can you be children of your heavenly Father' (Mt. 5:39, 44). Instead of extolling the martial virtues, Jesus declares 'Blessed are the peacemakers; they shall be called God’s children' (Mt. 5:10). And when Jesus was being arrested, Peter struck the servant of the high priest with his sword, cutting off his ear. But Jesus rebuked Peter: 'Put up your sword. Do you suppose that I cannot appeal for help to my Father, and at once be sent more than twelve legions of angels?' (Mt. 26:51-53). Jesus explicitly rejects a kingdom of this earth. To Pilate Jesus says at his trial: 'My kingdom does not belong to this world. If it did, my followers would be fighting to save me from the clutches of the Jews. My kingdom belongs elsewhere' (Jn. 18:36.).

However, there are some ambiguous verses in the Gospels which complicate this picture of Jesus. In Matthew 10:34, Jesus says: 'You must not think that I have come to bring peace to the earth; I have come not to bring peace but a sword'. Moreover, Christ physically drove the money changers from the temple (Jn. 2:15). And St Paul (Romans 13:4) insisted on submission to civil authority, since it came from God. 'It is not for nothing that they hold the power of the sword, for they are God’s agents of punishment bringing retribution on the offender'. Depending on how they are interpreted, such verses could be used to justify Christians fighting a holy war.

Nevertheless, the usual interpretation of the Gospels, most particularly in the early centuries, dwelt earnestly on Christ’s words of peace and rejection of violence. But the implications of Christ’s message of peace were not always self-evident when it came to fighting in war. The issue was not immediate, since the early Christians shared the exemption of the Jews from military service in the Roman army. Nor were the Jewish Christians attracted to the messianic revolutionary movements against the Romans, since they already recognised Jesus as their Messiah, whose kingdom was not of this world. Instead they were urged to endure persecution and even death until Jesus should shortly come again.

Jesus' admonitions against violence were taken very seriously, but did they amount to a pacifist position? Roland Bainton’s classic pacifist work, Christian Attitudes toward War and Peace, and C. John Cadoux’s The Early Christian Attitude to War,2  have had a strong influence on some Christian writers, particularly arguing that there was a 'fall' in the Church’s earlier strict pacifist views after the conversion of the Emperor Constantine in AD 310.3

Other scholars have challenged this. Louis J. Swift demonstrated a spectrum of early Christian views on violence and military service, before forming into a dualism supporting both a proto-pacifist view and also endorsing military service,4 a dualism which has revived significantly in Catholic thinking in recent decades.5

A leading authority on just war theory, James Turner Johnson, argued that the early Christian rejection of war-fighting and killing stemmed from their expectation that the Reign of God was imminent and not from pacifism. The gradual realisation that Jesus' Second Coming was taking longer than expected led the Christians gradually to focus on more immediate issues, such as military service. Johnson argues that the sizeable Christian presence in the Roman Army from at least AD 174 indicates that many Christians accepted the legitimacy of military service, and presumably had for some time. This does not mean that the ideal of non-violence was abandoned by Christians, but that it was lived out more fully by the monks and ascetics while most ordinary people adjusted to the demands of civil society, including sharing the burdens of defence.6 

Johnson contests the view that there was a revolutionary change in Christian attitudes with the conversion of Constantine.  In short, changes in the army, in Roman society and the Christian communities resulted in divergent practices in different parts of the Empire even from early in the second century AD, as the earlier millennial leanings gave way to a realisation that Christians had to contribute to the maintenance of the security of the Empire.7 

The problem for the Christians was how to maintain the prohibition against killing and violence but also to recognise the need to defend the innocent against violence.

The first major attempt to think through this problem came from Clement of Alexandria (AD c.150-c.215), whom Johnson regards as ambiguous at times, but who could also be seen as the first Christian just war thinker introducing two elements of what would later become standard just war theory, arguing for the defence of the Empire (just cause), on the authority of the emperor (right authority).8 


Considerably later, St Ambrose (c.339-97), like St Augustine after him, repeated Clement’s criteria of just cause and right authority, but augmented these with Roman law and the views of the Roman thinker, Cicero: a just war should be one of defence, agreements should be honoured, and with mercy shown the defeated. But drawing from examples of divinely sanctioned war in the Old Testament, Ambrose added that war could be waged to protect religious orthodoxy, beginning what was to be an ominous development.

Ambrose was a highly educated man and had been pretorian prefect of northern Italy before being elected bishop of Milan. Writing 50 years after the death of Constantine, Ambrose preserved the Christian presumption against the use of violence, unless it was needed to protect important social values. He explicitly rejected defending one’s own person with violence, but argued that charity demanded one protect one’s neighbour. He preserved the dual emphasis in Christian thinking, of a presumption against violence by stipulating that the clergy must refrain from violence, but arguing that the lay man may morally be required to defend the innocent though only by the force needed to prevent evil.9  Thus did Ambrose achieve a first synthesis of the Christian suspicion of violence and the classical Roman tradition requiring limited violence for good order and to defend the Empire?

Ambrose met Emperor Gratian in AD 379, resulting in orthodox Christianity becoming the official religion of the Empire, and heretics being subject to penalties and even death, on the grounds that heresy was treason to the state. Most of the barbarian tribes attacking Rome were heretics.10


This synthesis was developed further by St Augustine (AD 354-430), bishop of Hippo in North Africa, but as Johnson cautions, his influence was all but forgotten until his thought was revived by the jurist Gratian in the 12th century. There 'is no just war tradition prior to its coalescence in the Middle Ages around concepts drawn from canon law, theology, secular law, chivalric morality, and the habits of relations among princes'.11  Augustine’s significance stems from the fact that not until Christian civilisation had struggled out of the so-called Dark Ages seven centuries later, did his extant corpus of five million words assume enormous dimensions as that of the most sophisticated theologian in the West. Western thinkers began to develop theology and philosophy, and to recover the inheritance of classical Greece and Rome, in part through the eyes of Augustine, however inadequately he was understood.

Augustine’s thinking on just war underwent major changes. After his conversion from being a Manichee, he at first embraced a neo-Platonist view of cosmic order in which war may be the appropriate means to conform society to God’s order.12  The waging of war was widely accepted in Christian circles as legitimate in this violent and authoritarian age. Augustine also argued that the Church could persecute heretics because their spiritual health and that of the state were at risk, and hence persecution was a form of charity. He invoked the power of the state to force heretics and schismatics to rejoin the Church.13 

Whereas Roman thought centred on restoring the rights of an injured party, Augustine introduced a more theocratic notion with a penal emphasis, to restore the rights of God. 'Further, the subjective culpa or guilt of the enemy merited punishment of the enemy population without regard to the distinction between soldiers and civilians.'14  Nor did Augustine distinguish between offensive and defensive wars, since God had commanded wars of offence (e.g. Joshua against the citizens of Ai. See Joshua, chapter 8), and since remedying injuries was the key to his just cause rather than defence. Augustine did not allow soldiers to disobey their commanders even in an unjust war.15 

Instead of the earlier pagan priests of Rome giving their religious endorsement to a war,16 like Ambrose, Augustine gave a special role to the Christian bishop in determining the justice of a war. Johnson does not consider the determination by a bishop as constituting it as strictly a 'holy war' but as establishing that 'wars fought on God’s account are the most just of all wars'.17

But Augustine later lost confidence in human control over a rationally ordered universe. Because of the power of sin, Augustine came to realise that God’s order could not be readily realised through human thought or action. Hence the soldier could no longer simply be seen as carrying out a divine command when he killed. Augustine had to abandon his illusion that the whole world had 'become a choir praising Christ' as he wrote in 399-400.

No more could he naively imagine that the Emperor Constantine was God’s warrior, which had allowed Augustine to embrace the Empire’s policies of religious coercion.18  By the time he wrote the City of God, Augustine had concluded, as Markus put it, that: 'The quest for justice and order is doomed; but dedication to the impossible task is demanded by the very precariousness of civilised order in the world'. Against the threat of chaos and breakdown of civil order, a wise man will wage war justly but lamenting his unavoidable duty.19

Although he never reverted to any version of an early Christian 'pacifism', war now became for him one of the tragic necessities to which Christians must at times resort in order to check the savagery which is liable to break out between, as well as within, political societies.20

Despite the changes in his thinking, Augustine’s views on just war remained clearly identifiable. He drew from the Roman tradition the very idea of `just war? which included the requirements of

  • legitimate authority and
  • just cause, which was conceived as
    • repelling aggression or injury
    • retaking something wrongly taken, and
    • punishing wrongdoing.

Hence the requirement of just cause was long and well established.

Implied in his thought also were the criteria of

  • proportionality between the sacrifices and goals of war;
  • last resort;
  • and the goal of achieving peace.

Augustine also added a new condition for war, a right intention, meaning those dispositions inspired by Christianity to act justly in war, in both external action and especially interior disposition. The intention to restore justice must not give way to 'the love of violence, revengeful cruelty, fierce and implacable enmity, wild resistance and the lust of power'.21 

These developments gave significant shape to the emerging just war tradition in its ius ad bellum aspects, though little had developed explicitly about conditions for the just conduct of warfare, the ius in bello.22  Augustine’s legacy was deeply ambiguous, with elements of his thinking picked up in later centuries, laying the basis for the crusades.

A spurious work attributed to Augustine, Gravi de Pugna, went further than Augustine and assured Christians that God would be on their side in a just war and guarantee them victory. Justice would be confirmed by the result.23  It was likely to appeal greatly to later crusaders.

The Germanic warrior code

The barbarian incursions which swept Europe in succeeding centuries resulted in an astonishing collapse of learning and culture, and precipitated population decline. 'For practical purposes', Johnson wrote, 'there was in fact no just war doctrine in the Church from the time of Augustine until the Peace of God movement in the tenth and eleventh centuries ... began to open up debate on the protection of non-combatants and the authority to wield the sword.24

The warrior cultures of those tribes dominated Europe, so that as Christian learning and culture slowly revived, the resulting early medieval civilisations melded Christian and Germanic traditions into a highly militant culture based on the warrior code of honour won in battle. The earlier Roman restraints on warfare were submerged beneath those of tribal solidarity and honour earned from valour and plunder.25  Needless to say, Church personnel were constantly trying to curb this violence and the love of warfare.

These competing strands in European culture contested for dominance, with the Church trying to moderate the knightly lust for military glory, especially from the late 10th century with the efforts to restrict the days and seasons when fighting might occur (the Truce of God), and who could be involved or were not to be harmed (the Peace of God).

Eventually, the knightly code of chivalry emerged, defining honour partly in terms of protecting the weak against despoliation and oppression. Nevertheless, fighting among the knights was endemic in this period.26  This was a far cry from the early Christian presumption against killing.

Partly in an effort to curb the disorder in Europe and to give the knights something useful to do to absorb their energies, Pope Urban II launched the First Crusade in 1095 to rescue the Holy Places from Muslim rule, though Christian communities had lived as protected minorities under Muslim rulers for four centuries.27  The Byzantine rulers had initially appealed to the West for help against the Muslims but the alliance was tenuous, for the westerners deeply resented the superior culture of the Byzantines and in fact were often to fight against them, before the Fourth Crusade treacherously conquered Constantinople in AD 1204,  establishing a Latin kingdom which ruled there for nearly 60 years.28 

Gratian’s foundational synthesis and the crusades

With the first major revival of Roman law, Gratian’s Decretum (c.1148) began to consolidate a firm body of thought on just war. For many years Gratian’s canon law served as the standard text of jurisprudence on these areas, providing a comprehensive grounding for the redevelopment of just war tradition in the West. 'A just war is waged by an authoritative edict to avenge injuries', he wrote. This emphasised authority, a declaration of war, and the avenging of injuries. It set the conditions for just war, but followed Augustine in insisting on an inward disposition of love towards those against whom one was fighting.29  Gratian and later commentators concentrated on right authority in just war, while the theologians focused on just cause and right intention.30  But he also determined that excommunicates could be killed without committing murder, knights had a moral duty to wage war against heretics, and bishops could command wars for Church purposes.31 

This was a dangerous new doctrine, as Johnson commented. 'European civilisation would have been better off had the canonical doctrine of the crusade gone the way of the Truce of God, into oblivion'.32  The Peace of God movement in Europe was developed to protect church and other people from violence, and helped develop the concept of non-combatant immunity. But paradoxically it tended to encourage holy war outside Christendom, not restrain it, and it offered 'no restraints on war for religion against unbelievers'.33

The theoretical justification of the crusades took its classic form in the writings of the Church lawyers following Gratian, the Decretists (AD 1140-90), particularly Huguccio, who drew in a novel way from the example of God commanding wars and extermination of enemies in the Old Testament (Joshua 6: 21) to develop the doctrine of the crusade as the just war of the Church. While clergy could not take part in fighting, the pope spoke with the authority of God and could declare war and command Christians to fight in it. This went well beyond Augustine who limited the Church to inviting the secular authority to use its power against the enemies of the Church, but did not envisage a crusade against pagans or heretics, or call for a war for the faith.34  These initial efforts by the Church to espouse peace as a religious cause were to make war 'a pious duty in order to establish such peace, and the Church herself did not hesitate to identify enemies of the peace for the pious to make war against? the result was holy war.'35 

The crusade was at first immensely popular in Europe, and in the next five centuries was extended beyond fighting the Muslims to combating heretics in Europe and North Africa as well. However, the crusades in the Middle East led to atrocities on both sides and inflamed feeling with the supposed religious legitimation of the crusade and its mirror image in the Muslim jihad. Although a crusade was supposed to be conducted in accord with Christian ideals, in the fervour of combat these were often sacrificed to expediency or passion. The prospect of booty and glory also inevitably attracted all sorts of adventurers. The Church declared that death on crusade entitled one, after confession, to the indulgence - meaning the remission in the next life of the temporal punishment due to sin.36  This was easily corrupted into the idea that death on crusade automatically guaranteed one heaven, similar to the Muslim view of immediate admission to heaven if one died on jihad.

The debates over who had authority to make war and on what conditions were intimately linked with the struggle between the Church and temporal rulers. By the 13th century, the authority of the Church to command war was being pared back and limited to the Pope, in the case of crusades, or those bishops who were also temporal rulers.

Thomas Aquinas

St Thomas (1225-74) presented a short summary on the question of just war in his Summa Theologia, but did not go further than Gratian. He defended the right and duty to wage just war, and quoted Augustine commenting that Jesus `did not forbid soldiering? when he told soldiers: `Do violence to no man…and be content with your pay? (Luke 3:14) Aquinas reiterated the three ad bellum conditions.

  1. Right authority, possessed by the sovereign (the highest political authority).  Aquinas quoted Romans 13:4 that the civil authorities were agents who `hold the power of the sword? to punish lawbreakers. Aquinas added they also had to defend the common weal against external enemies.
  2. Just cause, to remedy some wrong. Again he quoted Augustine that a war was just when a state had to be punished for refusing to make amends for wrongs committed by its subjects or to restore what had been unjustly seized.
  3. Right intention, to secure peace, punish evildoers or promote the good.37

Aquinas situated his account of war in the context of Christian charity, the central virtue animating all others, including those of soldiers whose duty was to defend the community against unjust attack or evil to restore peace based on justice. Curiously, he gave no explicit consideration to ius in bello principles of proportionality and non-combatant immunity. One author suggests this was because Aquinas thought 'right conduct in battle is largely culture-dependent; what counts as praiseworthy or blameworthy action in combat will vary from place to place'. If the Christian soldier acted virtuously, right judgment would help them act appropriately in the widely differing circumstances they were likely to face. For Aquinas, morality was not governed by a precise set of rules, but stemmed from ingrained habits of virtue determining the right course of action.38  Brian Johnstone also interpreted Aquinas’s thinking on right conduct as being governed by this theology of charity and justice to all.39  Aquinas posited a central role for bishops and clerics in advising and counselling rulers and others about just wars so as to ensure moral consideration was adequate.40

Aquinas was reluctant to discuss crusades, presumably because he thought they did not cohere well with the early Christian prohibition against killing. He opposed forced conversions or wars of conversion, insisting on the need for a just cause declared by the appropriate authority to wage war against infidels or heretics before invoking a crusade. He approved of just wars against infidels who harmed Christians by persecution or blasphemies, but tacitly advised against such wars, thus by implication favouring toleration. He accepted limited persecution of heretics and infidels but did not link this to just wars or crusades.41  Further tragic outcomes of the call to crusade were the emergence of a violent anti-Semitism which became culturally entrenched, and the development of the Inquisitions to enforce doctrinal orthodoxy.

Emerging modern approaches to just war theories

Despite the crusades, an alternative tradition of thought in Europe began to take shape in an attempt to limit warfare and specify the moral conditions to govern the conduct of war.

This marks the beginning of the modern development in just war thinking, looking to universal human values and rejecting religious claims for war. But only from the 14th century did a right of non-combatant immunity begin to be recognised, as a result of Church moral scruple and the military tradition’s wish to limit casualties. Not until the end of the Middle Ages was the principle generally accepted. The slow emergence of the recognition of a right of non-combatant immunity is a caution not to assume that such principles are self-evident.42 

Values are mediated by cultures, and the moral conscience of humanity is a developing human construct, more dependent on circumstances than our contemporary beliefs in human rights and the dignity of the person might indicate. Indeed just war theory 'is not a moral absolute, demarcating the limits of that which is ideally, inflexibly and eternally just, but a time bound and culture bound formulation of a moral floor upon human conduct in war'.43

The crusading mentality also brought a particular fanaticism to the religious wars in Europe in the 16th century and overlapped with the savage conquest of the New World. The debates over the legitimacy of the conquista, especially at the School of Salamanca, with Francesco de Vitoria (1492-1546) and Francisco Suarez (1548-1617), and the Protestant Dutchman, Hugo Grotius (1583-1645) after the Thirty Years' War, contributed to the development of international law and the just war tradition.44  Against Spanish claims to wage war legitimately on the Indians, Vitoria declared that `Difference of religion is not a cause of just war'. He located the criteria for a just war not in religion but in reason and natural law known to all peoples.45  Vitoria and Suarez developed the ius in bello conditions for fighting, in response to the problems of their time.

Writing in The Law of War and Peace, Grotius emphasised defence as a just cause for war, and recognised a right of pre-emptive attack, saying the 'first just cause of war …is an injury, which even though not actually committed, threatens our persons or property'. The 'danger must be immediate, and as it were, at the point of happening',46  but that 'the bare possibility that violence may be some day turned on us gives us the right to inflict violence on others is a doctrine repugnant to every principle of justice.' One must be absolutely certain an attack is imminent, and other steps must be considered to defuse the situation. A nation was also required publicly to declare the reasons so that 'the whole human race, as it were, might weigh the justice of them'.47  Thus he laid the ground for modern international law and the positive law of war.

The ferocity of wars of religion eventually led to the widespread conviction that the cause of religion must be kept out of warfare as much as possible. Vitoria redeveloped just war theory as a systematic and coherent doctrine based on universal moral and legal principles. He denied that ideological wars, and wars based on difference of religion, were justified, and was particularly concerned about ius in bello. Grotius completed the secularisation of just war theory, but also insisted it be waged with moderation or proportionality.48

Ideological and 'holy' wars

The revolutionary movements of the 18th century changed the context for just war thinking, since the new emphasis on inalienable human rights provided a powerful challenge to the authority of the sovereign state. This virulent new ideological view justified war not just on the grounds of defence, but as a mission to spread its new belief in individual human rights, drawing on the entire resources of the nation to do so. With such an expansion in the destructive power of war, by the nineteenth century the right to wage war was narrowed to the single grounds of just defence; the other grounds of recovery of something taken and punishing evil lent themselves too readily to naked national interest.49

Meanwhile, the mentality of the crusade continued to trouble the Catholic Church even into modern times, as it resurfaced during the Spanish Civil War in 1936-39, with some Catholic bishops invoking the rhetoric of the 'crusade' against communism. The French philosopher, Jacques Maritain, with Georges Bernanos and François Mauriac, strongly opposed this crusade mentality. Maritain denounced it for writing a blank cheque in the name of religion to demonise one’s enemy, with the danger that the human rights of one’s adversary would not be recognised, and atrocities would be committed, violating the conditions for waging a just war.

Maritain insisted that the causes and conduct of war were complex and morally obtuse, with people lacking adequate information and acting out of mixed motivations of fear or anger, and often under compulsion. He lamented that this crusade mentality readily collapsed into a quasi-Manichaean view of the world, as a conflict between outright 'good' and 'evil'. He castigated this simplistic and self-serving attitude on both Catholic and communist sides in Spain as leading to the widespread violation of human rights. He insisted that the first condition for fighting a just war was to eliminate any religious motivation for the war. It was bad enough to have to kill someone in defence of a just cause, he said, but people must not kill in the name of Christ. No 'holy war' can serve the Reign of God, for war 'risks causing blasphemy of what is holy.'50

Thus the just war tradition in the West evolved only gradually, seeking to clarify rules of war to restore justice, as far as possible protect the innocent, and to restrict the damage caused by war. The churches and Christian values have played an important and distinctive part in the development of this tradition, but in interaction with wider cultural and political events so that the moral conditions governing war have been developed in the international forum in a secular context on the basis of universal ethical principles. It also must be acknowledged that secular and Enlightenment thinkers helped the Church decisively to abandon the crusade tradition of warfare which horrifies us so much today.51 

But as Maritain argued, a competing tradition of the crusade mentality, has repeatedly threatened the restraints of just war theory. These ideological wars, whether in religious or secular garb (e.g. under Nazism or communism), see the world through a quasi-Manichaean lens of moral absolutes, of Good versus Evil, with the demonizing of opponents, so that the ends are taken to justify the means, tending to the abuse of human rights, torture, ethnic cleansing, systematic mass killing of the innocent, etc. It is this ideological lens which makes such wars so morally pernicious.

Brian Johnstone also cautioned:

Vague metaphysical notions of condign punishment are not admissible, since they are not reasonably calculable. The range of action must be limited to what is needed to repel this particular aggression, and to prevent these perpetrators from further aggression. War may not be engaged in for quasi religious ends, such as making the world a better place, or making the world safe for democracy, or conquering 'evil', since such notions are simply indefinable and can never be used in assessing proportionality.52

Modern developments in Catholic thinking

Despite the efforts of recent popes and the Holy See to avert war during the twentieth century, there was little further formal development in Catholic teaching on just war until Pope Pius XII (1939-58) who responded to the trauma of World War II. While acknowledging that war may be needed to restore justice, he also realised that weapons of mass destruction and the ideology of total war made war destructive beyond reason, and could only be justified on the grounds of defence against unjust aggression.53  However, in 1956 he rejected conscientious objection as incompatible with the Church’s teaching on the just war and the duty of individual to obey state authorities.54

The just war tradition sees war as a rule-governed enterprise which presumes on moral and legal grounds that war is generally not justified, but with certain exceptions when our moral duty requires us to defend the innocent or supremely important human values.55 

But increasingly war itself was seen as the major problem, often resulting in new injustices. John XXIII in his 1963 encyclical, Peace on Earth, argued that in an atomic age, 'it no longer makes sense to maintain that war is a fit instrument with which to repair the violation of justice' (par. 127). James T. Johnson thought that Pope John here gave up too much, since the classic just war doctrine was about the repairing of justice.56  But as Hehir argues, later documents did not interpret John XXIII in a pacifist sense.57

However the Vatican Council’s Church in the Modern World made 'an evaluation of war with an entirely new attitude' (par. 78), especially because of the scale of modern war, and the expense of the arms race which diverted resources from the needy.58  It especially condemned 'any act of war aimed indiscriminately at the destruction of entire cities or extensive areas, along with their population, [as] a crime against God and man himself' (par. 80).

The Council praised those who chose non-violence rather than violence in defence of their rights, and for the first time supported a right of conscientious objection to bearing arms, reversing Pius XII’s position.59  Though some argued that this meant the Church had embraced pacifism, Hehir contended that the 'total content of recent Catholic teaching does not support a judgment that the Church has moved from a just-war ethic to a pacifist position.' Indeed, the Church in the Modern World itself recognised the right to legitimate defence once very means of peaceful settlement has been exhausted (par. 79), even while it urged the beginning of disarmament, not unilaterally, but in a controlled and verifiable way.60  The shift in Catholic thinking is also evident in the 1983 US bishops'statement, The Challenge of Peace, which began with a 'presumption against war'.

In an excellent review of developments in just war theory since World War II, Hehir traces the effects of the changing context of debate, from World War II, to Vietnam, the nuclear stand-off in the Cold War, and the Gulf War.  What has made more recent developments so difficult is that the inviolability of national sovereignty is being constrained by the burgeoning network of international organisations and agreements, human rights conventions and law. Though the world does not have an international authority with the power to outlaw war, nations still retain a right of self-defence. However the new international framework of governance is providing avenues for the resolution of conflict which did not exist before, and hence resort to war is hopefully becoming less necessary. The new networks of governance result from voluntary constraints on national sovereignty.

Secondly, war has changed. It has become extremely expensive, more disruptive to living conditions and more destructive, especially with the proliferation of new weapons, including weapons of mass destruction which make it extremely difficult to observe the principles of proportionality and non-combatant immunity. Moreover, public opinion seems to becoming less accepting of the need for war, and is insisting on other means of conflict resolution.61

John Paul II’s increasing restriction on the legitimacy of war

Hehir notes the contrast in statements by John Paul II. In Ireland in 1979 he declared: 'I proclaim with the conviction of my faith in Christ and with the awareness of my mission that violence is evil, that violence is unacceptable as a solution to problems ... Violence destroys what it claims to defend: the dignity of life, the freedom of human beings.' Yet elsewhere he recognised the right of defence against an unjust aggressor. How he balanced these contrary aspects was tested in his response to the 1990-91 Gulf War.

John Paul spoke on the conflict over 50 times, and became a strong opponent. Writing to President Bush, he implied that a just cause existed but that it would cause disproportionate damage and tragic consequences. In January 1991 he called the war 'a grave defeat for international law and the international community'.62  John Paul is certainly not a pacifist and invoked just war principles as in Kosovo and supported the UN intervention in East Timor, but he is emphasising that there are many more alternatives to war today and mechanisms to mediate conflicts.

This shift to a far less liberal interpretation of the just war criteria has been evident in the statements of John Paul II for some time. Right from his first encyclical, The Redeemer of Man (1979), the Pope urged an end to the arms race and warfare: 'the Church does not cease to ... beg everybody in the name of God and in the name of man: do not kill! Do not prepare for destruction and extermination...' (par. 16).

In his 1995 encyclical, The Gospel of Life, John Paul counted as a sign of hope 'at many levels of public opinion ... a new sensitivity ever more opposed to war as an instrument for the resolution of conflicts between peoples, and increasingly oriented to finding effective but "nonviolent" means to counter the armed aggressor' (italics in original). As Drew Christiansen commented, the Pope had not abandoned just war theory, but 'there is a growing presumption against the use of force and an increased appeal to strategies of nonviolence and negotiation.'63 

Exorcising past demons

It is not by accident that Pope John Paul II has repeatedly apologised for mistakes by Catholics and churchmen in the past, including for wars of religion and, by inference, the crusades. In 1994 he asked the cardinals: 'How can we be silent about so many kinds of violence perpetrated in the name of the faith? Religious wars, courts of the Inquisition, and other violations of the rights of the human person…'64  In March 2000 the Pope solemnly apologised in more general terms for mistakes and injustices committed in the name of the Church or by Catholics.65  The Pope clearly recognised that the use of violence at the service of the Church was an aberration which profoundly distorted Christ’s message of peacemaking, and violated people’s rights of conscience and religious freedom.

In a total repudiation of the crusade mentality, John Paul echoed the thought of Maritain in declaring to the diplomatic corps on 10 January 2002:

To kill in the name of God is a blasphemy and a perversion of religion, and I want to repeat this morning what I wrote in my message of Jan.1. 'It is a profanation of religion to proclaim oneself a terrorist in the name of God, to kill and violate human beings in the name of God. Terrorist violence, in fact, is contrary to faith in God the creator of the human person, a God that takes care of humanity and loves it.'

In the Pope’s view, if the world is to know peace, the world religions must denounce any appeal to violence in the name of God.


The just war tradition does not supply a simple stock of easy answers to the range of issues arising in war at different periods. But it does allow us to disaggregate key moral issues that need to be considered, to clearly identify and debate them. In the contemporary context, we need to stretch the just war criteria robustly and urgently to establish a new moral framework in which we can control a world proliferating with weapons of mass destruction.

Moral ambiguities abound in the application of just war criteria to specific circumstances, notably how to judge success and proportionality. However the Church cannot speak only on the level of principle, but within the limits of its competence must take part in the debate about how these principles bear on difficult situations.66


  1.  For key texts in the development of the western just war tradition, see Arthur F Holmes (ed.), War and Christian Ethics (Grand Rapids Mich.: Baker Book House, 1975).
  2. See Roland H. Bainton, Christian Attitudes toward War and Peace: a Historical Survey and Critical Re-evaluation (Nashville: Abingdon, 1960) and C. John Cadoux, The Early Christian Attitude to War (New York: Seabury Press, 1982).
  3. In his pacifist reading of the Catholic tradition, Ronald G. Musto, The Catholic Peace Tradition (Maryknoll: Orbis, 1986) leaves out material contrary to his thesis, especially during the patristic period.
  4. Louis J. Swift, The Early Church Fathers on War and Military Service (Wilmington Del.: Michael Glazier, 1983).
  5. See a contemporary pacifist orientation in Eileen Egan, Peace be with You: Justified Warfare or the Way of Nonviolence (Maryknoll: Orbis, 1999), and Brian Wicker (ed.), Studying War no more: from Just War to Just Peace (Grand Rapids Mich: William B. Eerdmans, 1993).
  6. See James Turner Johnson, The Quest for Peace: Three Moral Traditions in Western Cultural History, (Princeton NJ: Princeton University Press, 1987) 14-17.
  7. Swift (op. cit.) reflects the complex nature of the shift in Christian attitudes to killing and war, and how this varied in time and place.
  8. Johnson, op. cit., 20, 50.
  9. Ibid., 50-56.
  10. Frederick H. Russell, The Just War in the Middle Ages (Cambridge: Cambridge University Press, 1975/77), 13.
  11. Johnson, Quest for Peace, 58.
  12. R. A. Markus, `Saint Augustine’s Views on the “Just War”,’ in Sacred and Secular: Studies on Augustineand Latin Christianity (Variorum, 1994), 3-4.
  13. Russell, op. cit., 24-25.
  14. Ibid., 19-20.
  15. Ibid., 21-22.
  16. For the role of the fetiales, the Fetian priests of Rome, in rubberstamping recourse to war, see James Turner Johnson, The Just War Tradition and the Restraint of War: a Moral and Historical Inquiry (Princeton NJ: Princeton University Press), 154-55.
  17. Johnson, Quest for Peace, 60.
  18. For the historical background to religious coercion in Africa, see Peter Brown, Religion and Society in the Age of St Augustine (London: Faber and Faber, 1972).
  19. Markus, op., cit., 9-10.
  20. Ibid., 12.
  21. Johnson, Quest for Peace, 60-61.
  22. ibid., 68.
  23. Russell, op. cit., 26.
  24. ibid., 58.
  25. Johnson, Quest for Peace, 69.
  26. ibid., 75 ff.
  27. John Esposito, Islamic Threat: Myth or Reality? (New York: Oxford University Press, 1992), 40-41.
  28. See Karen Armstrong, Holy War: the Crusades and their Impact on Today’s World (New York: Anchor Books, 2001), 384 ff.
  29. Johnson, Just War Tradition, 121.
  30. Ibid., 123.
  31. Russell, op. cit., 74 ff.
  32. Johnson, Just War Tradition, 169.
  33. James Turner Johnson, The Holy War Idea in Western and Islamic Traditions, (University Park PA: Pennsylvania State University Press, 2001), 106.
  34. See Johnson, Just War Tradition, 156-60.
  35. Johnson, The Quest for Peace, 86. See Michael Walzer, `The Idea of Holy War in ancient Israel’, in J. Religious Ethics 20, 2 (Fall 1992), 215-228.
  36. Pope John VIII in the ninth century promised indulgences to those dying in defence of the Church and salvation to those dying fighting infidels and pagans, meaning the Saracens. See Russell, op. cit., 33.
  37. Aquinas, Summa Theologica, 2a, 2ae, q.40.
  38. Darrell Cole, `Thomas Aquinas on virtuous Warfare’, in J. Religious Ethics 27, 1 (Spring 1999), 69-70.
  39. Brian Johnstone CSsR, `The War on Terrorism: a Just War?’, Studia Moralia 40 (2002), 49 ff.
  40. Cole, op. cit., 76.
  41. Russell, op. cit., 258 ff.
  42. See Johnson, Just War Tradition, 131, 166-67.
  43. ibid., 150.
  44. Ibid., 174-75. See Gustavo Gutierrez on the ethical debate over the colonisation of Latin America in Las Casas: In Search of the Poor of Jesus Christ (Maryknoll NY: Orbis, 1993), particularly the famous condemnation of the Spanish by the Dominican preachers, p. 29.
  45. James Turner Johnson, `Just Cause Revisited’, in Elliott Abrams (ed.), Close Calls: Intervention, Terrorism, Missile Defense, and `Just War’ Today (Washington DC: Ethics and Public Policy Centre, 1998, 10-11.
  46. Ibid., 12-13.
  47. Ibid., 14.
  48. Johnson, Just War Tradition, 176-79.
  49. Johnson, `Just Cause Revisited’, 16-17.
  50. Jacques Maritain, `Preface’, in Professor A. Mendizabal, The Martyrdom of Spain: Origins of a CivilWar (London: Geoffrey Bles, 1938), 31 ff. See also Jose M. Sanchez, The Spanish Civil War as a Religious Tragedy (Notre Dame IN: University of Notre Dame Press, 1987) and Bernard Doering, Jacques Maritain and the French Catholic Intellectuals (Notre Dame IN: University of Notre Dame Press, 1983).
  51. James Turner Johnson gives a splendid account of recent developments in `The Just War idea and the American Search for Peace’, in G. Weigel and John R. Langan (eds.), The American Search for Peace: Moral Reasoning, Religious Hope, and National Security (Washington DC: Georgetown University Press, 1991), 69-101.
  52. Brian Johnstone, op. cit., 60.
  53. J. Bryan Hehir, `The Just-War Ethic and Catholic Theology: Dynamics of Change and Continuity’, in Thomas A. Shannon (ed.), War or Peace: The Search for New Answers (Maryknoll NY: Orbis, 1982), 17.
  54. Thomas A. Shannon, What are they saying about Peace and War? (Ramsey NJ: Paulis t Press, 1983), 25.
  55. Hehir, op. cit., 19.
  56. Johnson, `Just Cause revisited’, 26-27.
  57. Hehir, `Just –War Ethic…’, 23.
  58. Shannon, What are they saying…, 31.
  59. Hehir, op. cit., 21.
  60. Ibid., 23.
  61. See J. Bryan Hehir, `Just War Theory in a post Cold-War World’, J. Religious Ethics 20, 2 (Fall 1992),
    243 ff.
  62. ibid., 250.
  63. Drew Christiansen, `Peacemaking and the Use of Force: behind the Pope’s stringent Just-War Teaching’, America, 15 May 1999, 17.
  64. Pope John Paul II, `Reflections on the Great Jubilee of the Year 2000’, Spring 1994, in Luigi Accattoli, When a Pope asks Forgiveness: the mea culpa’s [sic] of John Paul II (New York: Alba House, 1998), 55- 58. See also Pope John Paul II, `Incarnationis Mysterium’, Origins, 28, 26 (December 10, 1998), 446-53, especially pars. 11-12.
  65. See `Appendix 1’ in The International Theological Commission, Memory and Reconciliation: the Churchand the Faults of the Past (Strathfield NSW: St Pauls Publications, 2000), 84-92. For a general context, see my `The Significance of the Pope’s Proposed Apologies for Errors by the Church’, Australasian Catholic Record, lxxvi, 4 (October 1999), 462-79.
  66. Christiansen, op. cit., 18