Notable quotations from Catholic social teaching on the theme of just war
The moral theory of the "just-war" or "limited-war" doctrine begins with the presumption which binds all Christians: we should do no harm to our neighbors; how we treat our enemy is the key test of whether we love our neighbor; and the possibility of taking even one human life is a prospect we should consider in fear and trembling.
The Challenge of Peace, #80
Just-war teaching has evolved, however, as an effort to prevent war; only if war cannot be rationally avoided, does the teaching then seek to restrict and reduce its horrors. It does this by establishing a set of rigorous conditions which must be met if the decision to go to war is to be morally permissible. Such a decision, especially today, requires extraordinarily strong reasons for overriding the presumption in favor of peace and against war.
The Challenge of Peace #83
Why and when recourse to war is permissible.
a) Just Cause: War is permissible only to confront "a real and certain danger," i.e., to protect innocent life, to preserve conditions necessary for decent human existence, and to basic human rights. . . .
b) Competent Authority: In the Catholic tradition the right to use force has always been joined to the common good; war must be declared by those with responsibility for public order, not by private groups or individuals. . . .
c) Comparative Justice: . . . .he question in its most basic form is this: do the rights and values involved justify killing?. . .
d) Right Intention: Right intention is related to just cause - war can be legitimately intended only for the reasons set forth above as a just cause. . . .
e) Last Resort. For resort to war to be justified, all peaceful alternatives must have been exhausted. . . .
f) Probability of Success. This criterion to apply, but its purpose is to prevent irrational resort to force or hopeless resistance when the outcome of either will clearly be disproportionate or futile. The determination includes a recognition that at times defense of key values, even against great odds, may be a "proportionate" witness. . . .
g) Proportionality: In terms of the "jus ad bellum" criteria, proportionality means that the damage to be inflicted and the costs incurred by war must be proportionate to the good expected by taking up arms.
. . .
The Challenge of Peace, #85 - 99
Even when the stringent conditions which justify resort to war are met, the conduct of war (i.e., strategy, tactics, and individual actions) remains subject to continuous scrutiny in light of two principles which have special significance today precisely because of the destructive capability of modern technological warfare. These principles are proportionality and discrimination.
The Challenge of Peace #101
When confronting choices among specific military options, the question asked by proportionality is: once we take into account not only the military advantages that will be achieved by using this means but also all the harms reasonably expected to follow from using it, can its use still be justified? We know, of course, that no end can justify means evil in themselves, such as the executing of hostages or the targeting of non-combatants. Nonetheless, even if the means adopted is not evil in itself, it is necessary to take into account the probable harms that will result from using it and the justice of accepting those harms. It is of utmost importance, in assessing harms and the justice of accepting them, to think about the poor and the helpless, for they are usually the ones who have the least to gain and the most to lose when war's violence touches their lives.
The Challenge of Peace #105
. . . another set of questions concerns the interpretation of the principle of discrimination. The principle prohibits directly intended attacks on non-combatants and non-military targets.
The Challenge of Peace #107
