HKB
(1) Whether it is lawful to be angry?
(2) Whether anger is a sin?
(3) Whether it is a mortal sin?
(4) Whether it is the most grievous of sins?
(5) Of its species;
(6) Whether anger is a capital vice?
(7) Of its daughters;
(8) Whether it has a contrary vice?
FIRST ARTICLE [II-II, Q. 158, Art. 1]
Whether It Is Lawful to Be Angry?
Objection 1: It would seem that it cannot be lawful to be angry. For Jerome in his exposition on Matt. 5:22, "Whosoever is angry with his brother," etc. says: "Some codices add 'without cause.' However, in the genuine codices the sentence is unqualified, and anger is forbidden altogether." Therefore it is nowise lawful to be angry.
Obj. 2: Further, according to Dionysius (Div. Nom. iv) "The soul's evil is to be without reason." Now anger is always without reason: for the Philosopher says (Ethic. vii, 6) that "anger does not listen perfectly to reason"; and Gregory says (Moral. v, 45) that "when anger sunders the tranquil surface of the soul, it mangles and rends it by its riot"; and Cassian says (De Inst. Caenob. viii, 6): "From whatever cause it arises, the angry passion boils over and blinds the eye of the mind." Therefore it is always evil to be angry.
Obj. 3: Further, anger is "desire for vengeance" [*Aristotle, Rhet. ii, 2] according to a gloss on Lev. 19:17, "Thou shalt not hate thy brother in thy heart." Now it would seem unlawful to desire vengeance, since this should be left to God, according to Deut. 32:35, "Revenge is Mine." Therefore it would seem that to be angry is always an evil.
Obj. 4: Further, all that makes us depart from likeness to God is evil. Now anger always makes us depart from likeness to God, since God judges with tranquillity according to Wis. 12:18. Therefore to be angry is always an evil.
On the contrary, Chrysostom [*Hom. xi in the Opus Imperfectum, falsely ascribed to St. John Chrysostom] says: "He that is angry without cause, shall be in danger; but he that is angry with cause, shall not be in danger: for without anger, teaching will be useless, judgments unstable, crimes unchecked." Therefore to be angry is not always an evil.
I answer that, Properly speaking anger is a passion of the sensitive appetite, and gives its name to the irascible power, as stated above (I-II, Q. 46, A. 1) when we were treating of the passions. Now with regard to the passions of the soul, it is to be observed that evil may be found in them in two ways. First by reason of the passion's very species, which is derived from the passion's object. Thus envy, in respect of its species, denotes an evil, since it is displeasure at another's good, and such displeasure is in itself contrary to reason: wherefore, as the Philosopher remarks (Ethic. ii, 6), "the very mention of envy denotes something evil." Now this does not apply to anger, which is the desire for revenge, since revenge may be desired both well and ill. Secondly, evil is found in a passion in respect of the passion's quantity, that is in respect of its excess or deficiency; and thus evil may be found in anger, when, to wit, one is angry, more or less than right reason demands. But if one is angry in accordance with right reason, one's anger is deserving of praise.