Just War Theory: Criteria, History & Modern Implications
The purpose of just war theory 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. It is a war declared for right and noble reasons and fought in a specific way. A just war isn’t inherently good; it’s a war deemed necessary or just in certain circumstances, when all other solutions have been exhausted. It is a necessary evil and a last resort.
In Antiquity, Cicero argued that acceptable reasons for war were limited to just vengeance or self-defense, including the defense of honor. Cicero’s attitude towards war reflects a lack of bellicosity, typical of the Romans. He argued that war could only be fought to protect the safety and honor of the state. Early Christians were mostly pacifists. St. Augustine, a Christian, believed the only justifiable reason for war was the pursuit of peace. He acknowledged war’s inevitability, considering it always a sin; however, if war was unavoidable, it should be waged with sadness. He argued that killing in defense of others could be justified with the right intention—not hatred, envy, or greed, but love and a desire for peace.
In the Middle Ages, Canon Law identified three legitimate reasons for war: recovering stolen goods, avenging injuries, and self-defense. Thomas Aquinas stated that the theory aims not to justify all wars but to prevent them by demonstrating that going to war, except under specific circumstances, is wrong. The intention was to encourage states to find alternative conflict resolution methods, prevent war, and limit its effects.
Conditions for a Just War
According to just war theory, several conditions must be met:
- Legal Authority: The war must be waged by a legally recognized authority, such as a government.
- Just Cause: The cause of war must be just.
- Right Intention: The war must be fought with the intention of establishing good or correcting evil.
- Reasonable Chance of Success: There must be a reasonable chance of success.
- Last Resort: War must be the last resort, after all diplomatic negotiations have failed.
- Proportionality: Only sufficient force must be used.
- Non-combatant Immunity: Civilians must not be involved.
During the Renaissance, Machiavelli, observing human selfishness, suggested harnessing this for the state’s good, while limiting violence.
The present UN Charter outlines two exceptions to the principle of refraining from war:
- Article 51: Inherent right to individual or collective self-defense if an armed attack occurs.
- Articles 39 & 42: The Security Council can determine threats to peace, breaches of the peace, or acts of aggression and take necessary action to maintain or restore international peace and security.
Jus ad Bellum and Jus in Bello
Jus ad bellum concerns the morality of going to war—the conditions under which states may resort to war or the use of armed force. Jus in bello concerns conduct in war, with three main principles:
- Discrimination: Civilians must never be deliberately targeted.
- Proportionality: Military targets can only be attacked when their military value outweighs the destruction caused.
- Compliance with the Laws of War: Soldiers must obey the laws of war, codified in international humanitarian law (Geneva Conventions, Additional Protocols, and other treaties).