Just War doctrine.


Where can I find books about the just war doctrine? Was it Augustine’s theory or Aquinas’s? When a soldier is fighting in a just war, is it a mortal sin on his conscious or his superiors? Is a pre-emptive war ever justified using the just war doctrine? Thank you


I cant help you in your search.

But I do know that the Just War Theory in the Catholic Church is being re-looked at because of the new and deadlier development of terrorism.


If it’s a just war, it is not a mortal sin. Period. Whether or not a pre-emptive war also qualifies as a just war would depend on the particular circumstances surrounding it. Fortunately, I’m not ever going to be called on to make those heavy decisions because it would hurt my brain I’m sure. When I read bloggers duking it out with each other on just war theory, my head hurts.


Not necessarily. Catholic just war tradition makes a distinction between ius ad bellum (the reasons for going to war in the first place) and ius in bello (the manner in which the war is conducted).

You might satsify the ius ad bellum criteria if the war was defensive and directed toward protecting against unjust aggression, but at the same time fail to satisfy the ius in bello criteria by using more force than is necessary or intentionally killing innocents.


Hello KateQ,

I did a poll and most Catholics believe that even killing in war on the side of injustice is not a mortal sin. Unfortunately the poll was lost in the great CAF cyber attack.

Many of our Church leaders presently at the Vatican are from Germany and Italy and were of fighting age in the WWII era. No doubt many of them had to participate as soldiers for Hitler in his evil war machine or be executed by the Nazis for for sedition. I have never heard of the Church demanding that WWII German and Italian veterans confess and repent of their sin in joining the German and Italian army or die in a state of mortal sin.

I do not believe that the Church teaches that it is even mortal sin to fight and kill in war on the side of injustice. I think the Just War Theory is more of a Church discussion on secular world activity. I do not think that the Church’s Just war theory is a binding on mortal sin like say the use of condoms or the like.

What do you think?


Steve and atsheeran,

Thank you for your responses. As I said in my post, just war theory tends to make my head hurt.

I agree with atsheeran that a just war does not necessarily validate or excuse all actions taken during that conflict. (CCC 2312 - 2314) But, barring participation in an intrinsically immoral act such as genocide, a soldier is expected to carry out his orders honorably and his participation in normal wartime activities do not carry the burden of mortal sin. That’s really what I meant to convey in my post.

When I was a teenager I used to go to a pacifist church with a girlfriend of mine. Their stance was clear – for the most part. Any killing was a sin. Period. Although at the time I was visiting the church (late 1950s), men in good standing in the congregation could serve in the Reserves since at the time, serving in the Reserves meant you were never going to see any action. Most of the young men served their military time as medics, however.

Being a Catholic is rather more complicated – always having to judge where our duty lies – duties toward peace, allegiance and duties to our government, duties for our family. We have the wisdom of hindsight and distance to know that Hitler’s actions in taking Europe to war were unjustified – but would the average German in the street have known that? He would want to protect his family and country. And he should expect to be able to rely on the prudential judgment of his leaders. (My in-laws were able to get out of Germany in 1939, so there was handwriting on the wall, but not everyone had the resources and capability of leaving.)

Of course when it came to the Holocaust and massive killing of Jews, gypsies, Ukrainians, and so on, then mortal sin was involved. There is historical evidence that men who could not bring themselves to participate in killing of Jews were actually excused that duty. (I can find that reference if you like.) So in a way the German command recognized that killing innocent, unarmed civilians is repugnant to people. It’s against the natural law – although I doubt they saw it that way.

Basically I’m agreeing with both your posts and I appreciate your thoughtful responses. Thanks.


Here is an excellent book that addresses the Just War Theory. Written by the late John Cardinal O’Connor of New York.

He wrote it in 1980 during the Cold War. He was a U.S. Navy admiral, as I recall … chief of chaplains.

Keep in mind that that the time, the “ordinary” nukes were city busting 5 megaton or 10 megaton monsters. (Our bombdropping aiming and delivery accuracy and reliability were very poor from 1945 to 2005. Pinpoint accuracy was only a dream and there was every assurance that the bombers wouldn’t be able to get near the targets. So they built large yield nukes. The Soviets actually fired one that was over 50 megatons.)

Anyway, the book is only one dollar at ABE books.

Here’s the link:


I understand how all these arguments plus 2000 years of Catholic publishing by folks like Augustine and Aquinas, who wrote in Latin and had to have their work translated into English with questionable clarity!! … how all this can give a headache!!

Stay with it. Accumulate the best library that you can. Keep reading. Eventually stuff starts to link and click.


just wars STINK. I refuse to hurt, maim, let alone end someone’s life for anything regardless. Let alone deny anyone a chnace to repent.


Aren’t you an honorable person!

This is how Hitler rolled over Europe and killed 6 million jews because of people like you. Better others die than actually stand up against evil. Better RED than DEAD right? Ruthless dictators love people who think this way. Goody for you.

Your daughter being raped or killed - oh no can’t interfer! Your next door neighbor needs your help and you wont lift a finger - the cops cant come in time - and all you will do is watch so that you can say you are “pure” even though you could have saved an innocent persons life. How selfish!

How admirable of you. Catholics pretty much developed the Just War Doctrine so clearly its justifyable and at times maybe MANDATORY. Yet you would do nothing while others do YOUR bidding to earn your freedom while they risk their lives - convenient for you! Glad you are not my next door neighbor.


I suppose that if some of these folks opposed to U.S. military operations in Iraq were around in WWII, they would say that “Hitler didn’t attack Pearl Harbor.”


Yep you right.

Pearl Harbor was attacked by Japan so therefore we attacked Germany!

Can you imagine todays liberals and media back then? We didnt win a battle for what 2 years while we ramped up.

Wrong war at wrong time! Thousands dieing in ONE day - impeach! Criticize the soldiers as murderers like Kerry did. Or like the DNC head and crazy guy Howard Dean saying that we are going to lose! Or senators like the Osama Moma or Bagdad Jim McDermott assisting the enemy. Can you imagine the criticisim they would have received back then?

Its war time and one party has declared war on our President not terrorists and has done everything to aid and abet them in trying to give Terrorist who never set foot on our soil US Constitutional rights! Never in history - but now we have pascifist who like the poster above


They stand for nothing and in fact help the enemy.


The president is no one’s but Satan’s. living on a passing world.


I don’t have a daughter. Nor a neighbor to be friendly with. Because the neightbors I got don’t give a hang bout me an my folks.


If possible, get a copy of the Catechism of the Catholic Church, Part Three, page 555, Avoiding war. Note number 2321: The prohibition of murder does not abrogate the right to render an unjust aggressor unable to inflict harm. Legitimate defense is a grave duty for whoever is responsible for the lives of others or the common good.


I don’t call nuttin’ that hurts, maims and injures people, let alone cuts short their lives, denying them a chance to repent, thus sending them to hell, a so called “duty”, all in the name of defense. Seems we were born to be violent since the start of time.


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