Just War Theory Revisited

While the U.S. government deliberates over possibly military action against Syria, we as Catholics have the opportunity to re-familiarize ourselves with the Church’s teaching on what makes a war just. Below is a helpful summary  by Fr. William Saunders from the Jan/Feb 2002 issue of Lay Witness magazine. 

Just cause

-The war must confront an unquestioned danger. St. Augustine, quoted by St. Thomas, said, “A just war is apt to be described as one that avenges wrongs, when a nation or state has to be punished, for refusing to make amends for the wrongs inflicted by its subjects, or to restore what it has seized unjustly.” The Catechism says that “the damage inflicted by the aggressor on the nation or community of nations must be lasting, grave, and certain” (no. 2309).

Proper authority
-The legitimate authority must decide if war is necessary and must be acting on behalf of the people.

Right intention
-The reasons for declaring the war must be based on just objectives and not a masking of ulterior motives. St. Thomas taught that the right intention is essential “so that they intend the advancement of good or the avoidance of evil.” St. Augustine also noted, “True religion looks upon as peaceful those wars that are waged not for motives of aggrandizement or cruelty, but with the object of securing peace or punishing evildoers, and of uplifting the good.” An evil intention (such as to destroy a race or to absorb another nation) can turn a legitimately declared war waged for just cause into a wrongful act.

Last resort
-All reasonable peaceful alternatives must have been exhausted or deemed impractical or ineffective. The contentious parties must strive to resolve their differences peacefully before engaging in war, which can be done through negotiation, mediation, or even embargoes. Here, too, we see the value of an international mediating body, such as the United Nations.


-The good that is achieved by waging war must not be outweighed by the harm. What good is it to wage war if it leaves the country in total devastation with no real victor? Modern means of warfare give great weight to this criterion insofar as weapons of mass destruction make for a real possibility of a devastating, disproportionate response.

Probability of success
-The achievement of the war’s purpose must have a reasonable chance of success. If a country can meet the above criteria, then it may justly enter war. Further, a country could come to the assistance of another country that is not able to defend itself provided these criteria are met.

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