Just and Unjust War
I hardly ever talk about Just War theory. Why? Because, with all due respect, I think the whole thing is baloney. I think we need to discard the notion of Just and Unjust war and replace it with a new way of thinking.
First of all, war is never just, as in acceptable, righteous, etc. It is hell for everyone involved.
The only relevant value-based category is not an essentially moral category, but a political one: necessary or unnecessary. That's it. We should guage wars or the desire to wage a war on if it is necessary or unnecessary.
Now, a quick note. The Just War theory suffers from the ambiguity of the term "just." "Just" can be used in the sense of "righteous" or morally-bound. The other sense of "Just" is "justified," i.e., acceptable. I would resonate with the second sense of the word but without any moral overtones. The positive necessity of a war does not grant it immunity from its intrinsic evil. There is absolutely nothing good about war. The converse is that peace and cooperation are the alternatives that we seek.
This of course flies in the face of fundamental Catholic moral principle which I also reject, "we cannot do evil that good may come of it." That is, if war is intrinsically evil, then we can't engage in it under any circumstances. That quite simply is impossible. In this life, you back away from one pile of crap only to squish into another. There is no avoiding it. So its best to evaluate then the different piles and navigate accordingly. Thus, when we fight wars that we deem are necessary, and this will be very infrequent, we do not fool ourselves into thinking we are doing a good thing: we are doing a necessary thing or a worthy thing.
Another way to look at this is that war is the action of a body politic of some sort and not an individual. War is a political action and falls under a different rubric of moral evaluation which really only allows for the categories of necessary or unnecessary.
When war is understood in terms of necessary or unnecessary, then the calculus that goes into evaluating it is much clearer and yeilds more reasonable and favorable results, less war and or milder wars, eventually the elimination of war.