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What is a Just War?

The traditional Just-War Theory derives from Christian theology. Saint Augustine is often regarded as the first to propose a doctrine of war and justice. The Saint appealed to the Bible and believed that certain wars were necessary to rectify evil.

Augustine's version was updated by Saint Thomas Aquinas, who established three requirements for a good war: the war had to be undertaken by a legitimate authority, for a just cause, and with the appropriate motives. Traditional just war theory concerns itself with two questions:

  1. When is it just to go to war and

  2. how may war be justly fought? Moral justifications for war are articulated in jus ad Bellum, while moral conduct of the war is conveyed in jus in Bello. The Just-War Theory is a set of military battle laws.

Principles of Just-War Theory

1. The Last Resort

Only when all peaceful alternatives have been exhausted can a fair war be fought. Force should only be used as a last option.

2. Legitimate Authority

A legitimate authority wages a just war. Individuals or organisations who are not part of the legitimate government cannot wage war.

3. Just Cause

A just war must be waged in reaction to an injustice. Self-defense against an assault is always a just war; nevertheless, the war must be conducted with the aim of correcting the inflicted harm.

4. Probability of Success

A battle must have a realistic chance of victory in order to be fair. A country cannot engage a war for a hopeless cause.

5. Right Intention

The primary goal of a just war is to restore peace. The peace that results from the conflict should, in particular, be greater than the peace that would have resulted from the absence of force. The goal of using force must be justice.

6. Proportionality

The violence in a just war must be proportional to the casualties suffered. The countries participating in the conflict must avoid excessive military action and employ only the amount of force that is absolutely required.

7. Civilian Casualties

The use of force must differentiate between militia and civilians. Innocent people must never be the aim of a conflict, and troops must always avoid killing civilians. Civilians' deaths are only permissible when they are the unavoidable victims of a military strike on a strategic target.

The case of Double Effect

The principle of double effect was developed in the Middle Ages to come to grips with the inevitable "spillage" of war. The core idea is that, although injuring or killing innocent people is always immoral, either might be justified if it is not the intended goal of a given act of war.

The idea is that actions of war may have two effects: the planned result is the harm or death of the legal military target, and the unintentional consequence is the injury or death of an innocent person. Acts of war may be forgiven as unexpected or incidental losses as long as they do not target and thereby seek to injure or kill innocent people according to the given justification.

The notion of double effect is complicated and causes perplexing problems. The use of nuclear bombs on Hiroshima and Nagasaki, for example, may be said not to have had the intention of injuring or killing non-combatants, and so the concept of double effect would legitimize hundreds of thousands of injuries and deaths. But is it truly justifiable given the heinous nature of the act as such casualties, however, were certainly anticipated? It is difficult to distinguish between unexpected and anticipated casualties.

Sun Tzu and Confucianism’s view

Confucianism adds a definitive moral component to the concept of legitimate authority, arguing that there is a certain, fixed moral center that states and state leaders must adhere to in order to be considered legitimate authorities and thus declare war.

Sun Tzu's Art of War, a Chinese military book written by Sun Tzu that explores the basic essence of war, expands on and emphasizes this topic. In the Art of War, Sun Tzu argues that war remains the worst method of settling disputes for nations and by its nature is an unjust act. Sun Tzu further argues that while wars are unjust by nature, circumstances might necessitate virtuous rulers to wage war, and while this might not make wars just, such wars of necessity, declared by virtuous rulers, were morally acceptable. Sun Tzu, therefore, goes beyond Confucian thinkers in his understanding of ruler morality and its relationship to battle.

Despite these variations, a significant tendency emerges from the Chinese interpretation of the legitimate authority requirements in just war theory– -the moral character of the leader is critical in deciding whether political power and hence the wars that it proclaims, are legitimate and so just.


Wars are not fought on moral grounds, though they are justified on moral grounds to make them appear less evil. Wars have a political end and in politics there’s no place for morality. Morality is a luxury that nations cannot afford since they live in an anarchical international arena in which they must be able to compete and win in order to serve and protect their populations effectively . As they say-survival truly is the strongest instinct.

We may always use certain criteria to determine whether a war is just or unjust, but is there actually any justification for the violence and loss of life and property that occurs after a war is declared? A moral justification won’t undo the cost of war. Certainly war must be the last resort to settle disputes.

Today, it is not uncommon for leaders to speak of peace and harmony, but it is also not uncommon for those same leaders to resort to violence to attain their ends, whenever time demands.


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