|The classic Just-War Theory has its origins in Christian theology. Saint Augustine is usually indentified as the first individual to offer a theory on war and justice. The Saint referred to the Bible and regarded some wars as necessary to amend an evil. Saint Thomas Aquinas revised Augustine's version, creating three criteria for a just war: the war needed to be waged by a legitimate authority, have a just cause, and have the right intentions. The moral justifcations for a war are expressed in jus ad bellum; whereas, the moral conduct of the war is expressed in jus in bello. The Just-War Theory is a set of rules for military combat.|
Principles of Just-War Theory
1. Last Resort
A just war can only be waged after all peaceful options are considered. The use of force can only be used as a last resort.
2. Legitimate Authority
A just war is waged by a legitimate authority. A war cannot be waged by individuals or groups that do not constitute the legitimate government.
3. Just Cause
A just war needs to be in response to a wrong suffered. Self-defense against an attack always constitutes a just war; however, the war needs to be fought with the objective to correct the inflicted wound.
4. Probability of Success
In order for a war to be just, there must be a rational possibility of success. A nation cannot enter into a war with a hopeless cause.
5. Right Intention
The pirmary objective of a just war is to re-establish peace. In particular, the peace after the war should excede the peace that would have succeeded without the use of force. The aim of the use of force must be justice.
The violence in a just war must be proportional to the casualties suffered. The nations involved in the war must avoid disproportionate military action and only use the amount of force absolutely necessary.
7. Civilian Casualties
The use of force must distinguish between the militia and civilians. Innocent citizens must never be the target of war; soldiers should always avoid killing civilians. The deaths of civilians are only justified when they are unaviodable victims of a military attack on a strategic target.
St. Thomas Aquinas