Question II

GRATIAN. As to what is asked—what war is just—Isidore says in Book XVIII of the Etymologies:

A war is just when it is waged by edict for the recovery of property or for the purpose of repelling men. § 1. A judge is so called because he declares right to the people, or because he decides by right. To decide by right is to judge justly. For he is not a judge if justice is not in him.

Likewise Augustine in the book of Questions, [VI, question 10]. The Lord our God commands Joshua son of Nun to establish ambushes behind him—that is, warriors lying in ambush to ambush the enemies. From this we are admonished that this is not done unjustly by those who wage a just war, so that above all the just man should consider nothing in these matters except that he undertake a war which it is lawful for him to wage. For it is not lawful for all. But when he has undertaken a just war, whether he fights openly or by ambushes makes no difference to justice. Just wars are customarily defined as those that avenge injuries, as when some nation or state that is to be attacked in war has neglected either to punish what was wickedly done by its own people or to restore what was taken away through injuries. But that kind of war also is undoubtedly just which God commands, who knows what ought to be done to each person; in such a war the commander of the army or the people itself is to be judged not so much the author of the war as its minister. GRATIAN. Therefore, since a just war is one waged by edict or one by which injuries are avenged, it is asked how just wars were waged by the children of Israel. Augustine writes thus concerning these in Questions on Numbers, [question 44, on c. 20]:

It is certainly to be noted how just wars were waged by the children of Israel against the Amorites. For harmless passage was denied, which by the most equitable right of human fellowship ought to have lain open.