Catholic Just War Theory
Taken from the U.S. Catholic Bishops’ 1983 The Challenge of Peace
The theory of the just war or limited war begins with a presumption that binds all Christians, we must love our neighbors and our enemies. The possibility of taking even one human life must be a prospect we should consider with fear and trembling.
Jus ad Bellum: Criteria that must be met in order for a war to be considered just.
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 life existence, and to basic human rights.
Competent Authority: The right to use force must be joined with the common good; war must be declared by those with responsibility for public order, not by private groups or individuals.
Comparative Justice: No state should act on the basis that it has “absolute justice” on its side. Every party to a conflict must acknowledge the limits of its “just cause” and the consequent requirement to use only limited means in pursuit of its objectives.
Right Intention: War can be legitimately intended for only the reasons set forth as a just cause.
Last Resort: For war to be justified, all peaceful alternatives must have been exhausted.
Probability of Success: This is a difficult 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
Proportionality: The destruction to be inflicted and the costs incurred by war must be proportionate to the good expected by taking up arms. Destruction applies in both the temporal and spiritual sense.
Jus in Bello: Criteria that must be met in order for actions within war to be considered just.
Discrimination: This criterion requires that actions within a war must never be “total war”, nuclear war, and must never target civilian populations or non-military targets.
Proportionality: Destruction caused by actions in war must be proportionate to the good expected by the actions. Destruction applies in both the temporal and spiritual sense.