Tuesday, May 27, 2014
Vengeance consists in the infliction of a penal evil on one who has sinned. Accordingly, in the matter of vengeance, we must consider the mind of the avenger. For if his intention is directed chiefly to the evil of the person on whom he takes vengeance and rests there, then his vengeance is altogether unlawful: because to take pleasure in another's evil belongs to hatred, which is contrary to the charity whereby we are bound to love all men. Nor is it an excuse that he intends the evil of one who has unjustly inflicted evil on him, as neither is a man excused for hating one that hates him: for a man may not sin against another just because the latter has already sinned against him, since this is to be overcome by evil, which was forbidden by the Apostle, who says (Romans 12:21): "Be not overcome by evil, but overcome evil by good."
If, however, the avenger's intention be directed chiefly to some good, to be obtained by means of the punishment of the person who has sinned (for instance that the sinner may amend, or at least that he may be restrained and others be not disturbed, that justice may be upheld, and God honored), then vengeance may be lawful, provided other due circumstances be observed. (Summa Theologiae II-II.108.1)