War and peace

What you'll learn

• How Christianity has contributed to debates about war, peace and the use of force.
• How Just War Theory works through jus ad bellum, jus in bello and jus post bellum.
• How Augustine and Aquinas shaped Christian thinking about morally justified war.
• How to evaluate pacifism, nuclear war, and real conflicts in an Edexcel essay.

Why war and peace is an ethics issue

War is not just a political event. It raises moral questions about killing, defence, justice, intention, civilians, weapons, punishment and peace after conflict. Religious ethics asks whether war can ever be morally right — and, if so, under what limits.

For Edexcel, you need to know the contribution of at least one religion. The most natural religion here is Christianity, because the set thinkers are Augustine and Aquinas, both major Christian theologians.

Christianity: a tension in the sacred texts

Christianity contains both pacifist and Just War strands.

Some New Testament teachings seem strongly pacifist. Jesus says, “Blessed are the peacemakers” in Matthew 5:9, “Love your enemies” in Matthew 5:44, and “turn the other cheek” in Matthew 5:39. When Jesus is arrested, he tells Peter to put away his sword, saying that “all who take the sword will perish by the sword” in Matthew 26:52.

However, other texts have been used to support limited force. Romans 13 teaches that governing authorities have a role in restraining wrongdoing. Some Christians argue this means the state may use force to protect the innocent and preserve justice.

Just War Theory

Just War Theory is not a blank cheque for violence. It is meant to limit war by asking whether force is genuinely necessary, proportionate and directed towards peace.

Augustine: war as a tragic duty

Augustine of Hippo was a fourth- and fifth-century Christian theologian. He argued that peace is the proper goal of human society. His famous idea of peace is tranquillitas ordinis, meaning the “tranquillity of order”: peace exists when society is rightly ordered under justice.

Augustine did not think war was good in itself. He saw it as a tragic consequence of sin. However, he believed that rulers might have a duty to use force to punish wrongdoing, restrain evil and protect the innocent.

For Augustine, the inner attitude matters. A Christian should not fight out of cruelty, revenge, greed or hatred. If force is used, it must be motivated by love of neighbour and aimed at restoring peace.

Aquinas: three classic conditions

Thomas Aquinas, a thirteenth-century theologian, developed Just War thinking in the Summa Theologiae. He asked whether it is always sinful to wage war and gave three key conditions.

1. Sovereign authority: war must be declared by the proper public authority, not by private individuals.
2. Just cause: those attacked must deserve it because of some serious wrong, such as aggression.
3. Right intention: the aim must be the advancement of good or the avoidance of evil.

Aquinas builds on Augustine. Like Augustine, he sees war as justified only if it is ordered towards peace and justice.

The three parts of Just War Theory

Jus ad bellum: justice before war

Common criteria include:

• Just cause: for example, self-defence or protecting innocent people.
• Legitimate authority: war must be authorised by a recognised authority.
• Right intention: the aim must be peace and justice, not revenge or gain.
• Last resort: diplomacy, sanctions and negotiation must have been seriously tried.
• Proportionality: the expected good must outweigh the expected harm.
• Reasonable chance of success: it is wrong to cause massive suffering for a hopeless aim.

Jus in bello: justice during war

The key principles are:

• Discrimination: soldiers must distinguish between combatants and non-combatants.
• Non-combatant immunity: civilians should not be deliberately targeted.
• Proportionality of means: the force used must not be excessive.

Jus post bellum: justice after war

This includes reconstruction, reconciliation, fair trials, avoiding revenge, and building a stable peace.

Why Just War Theory developed

Early Christianity often leaned towards pacifism because Christians followed Jesus’ non-violent example and were a minority within the Roman Empire.

After Christianity became connected with political power, especially after Constantine, Christians had to ask new questions. Could a Christian emperor defend citizens? Could the state punish invaders? Could love of neighbour require protecting victims by force?

Just War Theory developed as a middle position between two extremes:

• Realism: the view that war is mainly about power and survival, not morality.
• Pacifism: the view that war or violence is morally unacceptable, either always or in many cases.

Examples of wars to evaluate

The Second World War

The Second World War is often used as a strong Just War example. The defeat of Nazi aggression gives a powerful just cause, and the liberation of occupied countries suggests a morally serious aim.

However, the war also raises problems. The bombing of Dresden and the atomic bombings of Hiroshima and Nagasaki raise questions about discrimination and proportionality. Even a war with a just cause can involve unjust methods.

The Iraq War 2003

The Iraq War is often used as a challenge to Just War Theory in practice. Supporters argued that Saddam Hussein was a tyrant and that weapons of mass destruction posed a threat. Critics argue that the evidence was weak, the war lacked clear United Nations authorisation, and the post-war planning was poor.

This makes Iraq useful for evaluating last resort, legitimate authority, reasonable chance of success and jus post bellum.

Nuclear war

Nuclear weapons create special problems for Just War Theory because their effects are massive, long-lasting and hard to control. Blast, fire, radiation and environmental damage make discrimination between combatants and civilians extremely difficult.

A limited nuclear strike might be defended by some as deterrence or self-defence, but full-scale nuclear war appears almost impossible to justify because it would be indiscriminate and disproportionate.

Pacifism

Absolute pacifism

Absolute pacifism rejects all war and violence in every circumstance. Many Christian pacifists appeal to Jesus’ teaching to love enemies and refuse retaliation.

Its strength is moral consistency. Its weakness is practicality: critics argue it may fail to protect innocent people from genocide, invasion or oppression.

Relative or selective pacifism

Relative pacifism, also called selective pacifism, rejects particular wars rather than all wars. A selective pacifist might oppose the Iraq War but support defensive resistance against invasion.

Its strength is flexibility. Its weakness is that it may become very close to Just War Theory, so the difference can become blurred.

Nuclear pacifism

Nuclear pacifism specifically rejects nuclear weapons and nuclear war. A nuclear pacifist may not oppose every conventional war, but argues that nuclear weapons are uniquely immoral because they are indiscriminate and disproportionate.

Pacifist movements and pressure groups

Pacifist movements try to shape public conscience, law and government policy.

Examples include:

• Quakers, who have a long history of Christian pacifism, conscientious objection and humanitarian work.
• Fellowship of Reconciliation, a faith-based peace movement opposing war and promoting non-violence.
• Pax Christi, a Catholic peace movement focused on reconciliation, disarmament and justice.
• Campaign for Nuclear Disarmament, known as CND, which campaigns against nuclear weapons.
• Stop the War Coalition, which has organised protests against modern conflicts such as Iraq.

Their success is mixed. They may not always stop wars, but they can influence public debate, support conscientious objectors, challenge government narratives and keep moral scrutiny alive.

Is pacifism practical?

Pacifism has a powerful moral appeal because it refuses to mirror the violence it condemns. It also highlights the human cost of war, especially for civilians.

However, critics argue that absolute pacifism can be unrealistic in the face of aggressive evil. Augustine would argue that love of neighbour may require force to protect victims. Aquinas would ask whether legitimate authority, just cause and right intention are present.

Selective and nuclear pacifism are often more practical because they allow careful moral judgement. But they may struggle to explain exactly where the line should be drawn.

Does war ever have advantages?

Some argue that war has produced technological development: radar, computing, medicine, aviation, nuclear energy, GPS and the internet all have links to war or military competition.

But this is not a strong moral justification for war. A benefit that comes from war does not prove war was right. A Just War judgement must still consider intention, proportionality, civilian harm and whether peaceful alternatives were available.

Overall evaluation: Augustine and Aquinas today

Augustine’s strength is realism. He recognises that a fallen world may require force to restrain evil, but he insists that peace must remain the goal. Aquinas gives clearer criteria, especially authority, just cause and right intention.

The weakness is that governments can manipulate Just War language to justify wars they already want to fight. Iraq 2003 is a common example used by critics. Nuclear weapons also expose serious limits in the theory, because discrimination and proportionality are so difficult to maintain.

A balanced judgement might be: Just War Theory is highly successful as a moral framework for criticising war, but less successful at preventing unjust wars in practice. Pacifism gives a powerful witness to peace, but absolute pacifism may be difficult to defend when innocent life is under immediate threat.