In my last column I gave a brief overview of the Church’s teaching on self-defense. The same basic principle can at times be invoked on a larger scale, even among nations. While some of the ideas which would influence the Christian articulation of what is known as the “Just War Theory” predate Christianity, it was really the work of theologians like St. Augustine in the 4th Century who were able to reconcile such principles with the Gospel. In the end, it was believed (and is still believed) that Christians can only reconcile their faith and fighting a war, if certain, very demanding, criteria were met. Thus war might be seen as an act of legitimate self-defense on a large scale.

Generally speaking, the Church abhors war and the inevitable destruction and loss of life it brings. However, it also recognizes that in a fallen world at times war may be the only option which stands in the way of even greater evil being perpetrated. How does one know if such a point has been reached? In the classic formulation a war is only justified if all of the following criteria are met.

First, there must be a just cause. This can mean that I am defending against an unjust attacker or defending the rights of the vulnerable. It might also mean I am attempting to stop an attack before it happens or even that I am regaining ground unjustly taken. Regardless of the specifics, it must be demonstrated that the cause is one of justice or defense — not hatred, jealousy, greed or vengeance.

This also means one’s intentions must be as good and right as the cause is just. Wrong intentions, even with a just cause, destroy or weaken the legitimacy of the cause.

Second, there must be reason to believe that the good to be achieved will be proportionate to the evil to be suffered. This is perhaps the most difficult criteria to satisfy simply because the actual proportion cannot be known ahead of time. And, at times, the hoped for good may not end up being the actual good achieved. One must be honest and reasonable about any such assessment given the information at hand.

Third, those with legitimate authority are the ones who make the final determination. It is their responsibility in light of that authority. This also means that the moral responsibility for the decision to engage in war or not, lies squarely with those tasked to make such decisions. Individual soldiers have responsibility for the actions they engage in or refuse to engage in during that conflict, but the decision to engage in war in the first place is the responsibility of those with authority. An individual soldier is not responsible for the decision to go to war or not, but they must still conduct themselves so as not to engage in unnecessary or excessive harm.

Fourth, there must be a probability of success. A conflict is not engaged in simply to cause destruction or to harass an enemy. Rather, the goal of the conflict must be to right the wrong or eliminate the threat from causing further or future harm. This principle applies primarily to those actions which may be pre-emptive in nature. Fighting against an obviously stronger enemy because one is attacked may be legitimate even if it is a desperate attempt to defend one’s country, but intentionally beginning a fight that cannot reasonably be won is another story.

Finally, one must exhaust all other avenues of settling a conflict first. War must be the last resort after reasonable diplomatic alternatives have failed or as the last effort to defend one’s homeland.

These criteria are difficult and challenging. They demonstrate clearly that not all moral issues have easy black and white answers. Rather, they provide some basic guidelines to help us guide our choices in confusing and difficult circumstances.