Summa Th. II-II EN Qu.64 a.3
Objection: 1. It would seem lawful for a private individual to kill a man who has sinned. For nothing unlawful is commanded in the Divine law. Yet, on account of the sin of the molten calf, Moses commanded (Ex 32,27): "Let every man kill his brother, and friend, and neighbor." Therefore it is lawful for private individuals to kill a sinner.
2. Further, as stated above (Article , ad 3), man, on account of sin, is compared to the beasts. Now it is lawful for any private individual to kill a wild beast, especially if it be harmful. Therefore for the same reason, it is lawful for any private individual to kill a man who has sinned.
3. Further, a man, though a private individual, deserves praise for doing what is useful for the common good. Now the slaying of evildoers is useful for the common good, as stated above (Article ). Therefore it is deserving of praise if even private individuals kill evil-doers.
On the contrary Augustine says (De Civ. Dei i) [*Can. Quicumque percutit, caus. xxiii, qu. 8]: "A man who, without exercising public authority, kills an evil-doer, shall be judged guilty of murder, and all the more, since he has dared to usurp a power which God has not given him."
I answer that As stated above (Article ), it is lawful to kill an evildoer in so far as it is directed to the welfare of the whole community, so that it belongs to him alone who has charge of the community's welfare. Thus it belongs to a physician to cut off a decayed limb, when he has been entrusted with the care of the health of the whole body. Now the care of the common good is entrusted to persons of rank having public authority: wherefore they alone, and not private individuals, can lawfully put evildoers to death.
Reply to Objection: 1. The person by whose authority a thing is done really does the thing as Dionysius declares (Coel. Hier. iii). Hence according to Augustine (De Civ. Dei i, 21), "He slays not who owes his service to one who commands him, even as a sword is merely the instrument to him that wields it." Wherefore those who, at the Lord's command, slew their neighbors and friends, would seem not to have done this themselves, but rather He by whose authority they acted thus: just as a soldier slays the foe by the authority of his sovereign, and the executioner slays the robber by the authority of the judge.
2. A beast is by nature distinct from man, wherefore in the case of a wild beast there is no need for an authority to kill it; whereas, in the case of domestic animals, such authority is required, not for their sake, but on account of the owner's loss. On the other hand a man who has sinned is not by nature distinct from good men; hence a public authority is requisite in order to condemn him to death for the common good.
3. It is lawful for any private individual to do anything for the common good, provided it harm nobody: but if it be harmful to some other, it cannot be done, except by virtue of the judgment of the person to whom it pertains to decide what is to be taken from the parts for the welfare of the whole.
Objection: 1. It would seem lawful for clerics to kill evil-doers. For clerics especially should fulfil the precept of the Apostle (1Co 4,16): "Be ye followers of me as I also am of Christ," whereby we are called upon to imitate God and His saints. Now the very God whom we worship puts evildoers to death, according to Ps 135,10, "Who smote Egypt with their firstborn." Again Moses made the Levites slay twenty-three thousand men on account of the worship of the calf (Ex 32), the priest Phinees slew the Israelite who went in to the woman of Madian (Nb 25), Samuel killed Agag king of Amalec (1R 15), Elias slew the priests of Baal (1R 18), Mathathias killed the man who went up to the altar to sacrifice (1 Mach. 2); and, in the New Testament, Peter killed Ananias and Saphira (Ac 5). Therefore it seems that even clerics may kill evil-doers.
2. Further, spiritual power is greater than the secular and is more united to God. Now the secular power as "God's minister" lawfully puts evil-doers to death, according to Rm 13,4. Much more therefore may clerics, who are God's ministers and have spiritual power, put evil-doers to death.
3. Further, whosoever lawfully accepts an office, may lawfully exercise the functions of that office. Now it belongs to the princely office to slay evildoers, as stated above (Article ). Therefore those clerics who are earthly princes may lawfully slay malefactors.
On the contrary It is written (1Tm 3,2-3): "It behooveth . . . a bishop to be without crime [*Vulg.: 'blameless.' 'Without crime' is the reading in Tit. 1:7] . . . not given to wine, no striker."
I answer that It is unlawful for clerics to kill, for two reasons. First, because they are chosen for the ministry of the altar, whereon is represented the Passion of Christ slain "Who, when He was struck did not strike [Vulg.: 'When He suffered, He threatened not']" (1P 2,23). Therefore it becomes not clerics to strike or kill: for ministers should imitate their master, according to Si 10,2, "As the judge of the people is himself, so also are his ministers." The other reason is because clerics are entrusted with the ministry of the New Law, wherein no punishment of death or of bodily maiming is appointed: wherefore they should abstain from such things in order that they may be fitting ministers of the New Testament.
Reply to Objection: 1. God works in all things without exception whatever is right, yet in each one according to its mode. Wherefore everyone should imitate God in that which is specially becoming to him. Hence, though God slays evildoers even corporally, it does not follow that all should imitate Him in this. As regards Peter, he did not put Ananias and Saphira to death by his own authority or with his own hand, but published their death sentence pronounced by God. The Priests or Levites of the Old Testament were the ministers of the Old Law, which appointed corporal penalties, so that it was fitting for them to slay with their own hands.
2. The ministry of clerics is concerned with better things than corporal slayings, namely with things pertaining to spiritual welfare, and so it is not fitting for them to meddle with minor matters.
3. Ecclesiastical prelates accept the office of earthly princes, not that they may inflict capital punishment themselves, but that this may be carried into effect by others in virtue of their authority.
Objection: 1. It would seem lawful for a man to kill himself. For murder is a sin in so far as it is contrary to justice. But no man can do an injustice to himself, as is proved in Ethic. v, 11. Therefore no man sins by killing himself.
2. Further, it is lawful, for one who exercises public authority, to kill evil-doers. Now he who exercises public authority is sometimes an evil-doer. Therefore he may lawfully kill himself.
3. Further, it is lawful for a man to suffer spontaneously a lesser danger that he may avoid a greater: thus it is lawful for a man to cut off a decayed limb even from himself, that he may save his whole body. Now sometimes a man, by killing himself, avoids a greater evil, for example an unhappy life, or the shame of sin. Therefore a man may kill himself.
4. Further, Samson killed himself, as related in Jg 16, and yet he is numbered among the saints (He 11). Therefore it is lawful for a man to kill himself.
5. Further, it is related (2M 14,42) that a certain Razias killed himself, "choosing to die nobly rather than to fall into the hands of the wicked, and to suffer abuses unbecoming his noble birth." Now nothing that is done nobly and bravely is unlawful. Therefore suicide is not unlawful.
On the contrary Augustine says (De Civ. Dei i, 20): "Hence it follows that the words 'Thou shalt not kill' refer to the killing of a man---not another man; therefore, not even thyself. For he who kills himself, kills nothing else than a man."
I answer that It is altogether unlawful to kill oneself, for three reasons. First, because everything naturally loves itself, the result being that everything naturally keeps itself in being, and resists corruptions so far as it can. Wherefore suicide is contrary to the inclination of nature, and to charity whereby every man should love himself. Hence suicide is always a mortal sin, as being contrary to the natural law and to charity. Secondly, because every part, as such, belongs to the whole. Now every man is part of the community, and so, as such, he belongs to the community. Hence by killing himself he injures the community, as the Philosopher declares (Ethic. v, 11). Thirdly, because life is God's gift to man, and is subject to His power, Who kills and makes to live. Hence whoever takes his own life, sins against God, even as he who kills another's slave, sins against that slave's master, and as he who usurps to himself judgment of a matter not entrusted to him. For it belongs to God alone to pronounce sentence of death and life, according to Dt 32,39, "I will kill and I will make to live."
Reply to Objection: 1. Murder is a sin, not only because it is contrary to justice, but also because it is opposed to charity which a man should have towards himself: in this respect suicide is a sin in relation to oneself. In relation to the community and to God, it is sinful, by reason also of its opposition to justice.
2. One who exercises public authority may lawfully put to death an evil-doer, since he can pass judgment on him. But no man is judge of himself. Wherefore it is not lawful for one who exercises public authority to put himself to death for any sin whatever: although he may lawfully commit himself to the judgment of others.
3. Man is made master of himself through his free-will: wherefore he can lawfully dispose of himself as to those matters which pertain to this life which is ruled by man's free-will. But the passage from this life to another and happier one is subject not to man's free-will but to the power of God. Hence it is not lawful for man to take his own life that he may pass to a happier life, nor that he may escape any unhappiness whatsoever of the present life, because the ultimate and most fearsome evil of this life is death, as the Philosopher states (Ethic. iii, 6). Therefore to bring death upon oneself in order to escape the other afflictions of this life, is to adopt a greater evil in order to avoid a lesser. In like manner it is unlawful to take one's own life on account of one's having committed a sin, both because by so doing one does oneself a very great injury, by depriving oneself of the time needful for repentance, and because it is not lawful to slay an evildoer except by the sentence of the public authority. Again it is unlawful for a woman to kill herself lest she be violated, because she ought not to commit on herself the very great sin of suicide, to avoid the lesser sir; of another. For she commits no sin in being violated by force, provided she does not consent, since "without consent of the mind there is no stain on the body," as the Blessed Lucy declared. Now it is evident that fornication and adultery are less grievous sins than taking a man's, especially one's own, life: since the latter is most grievous, because one injures oneself, to whom one owes the greatest love. Moreover it is most dangerous since no time is left wherein to expiate it by repentance. Again it is not lawful for anyone to take his own life for fear he should consent to sin, because "evil must not be done that good may come" (Rm 3,8) or that evil may be avoided especially if the evil be of small account and an uncertain event, for it is uncertain whether one will at some future time consent to a sin, since God is able to deliver man from sin under any temptation whatever.
4. As Augustine says (De Civ. Dei i, 21), "not even Samson is to be excused that he crushed himself together with his enemies under the ruins of the house, except the Holy Ghost, Who had wrought many wonders through him, had secretly commanded him to do this." He assigns the same reason in the case of certain holy women, who at the time of persecution took their own lives, and who are commemorated by the Church.
5. It belongs to fortitude that a man does not shrink from being slain by another, for the sake of the good of virtue, and that he may avoid sin. But that a man take his own life in order to avoid penal evils has indeed an appearance of fortitude (for which reason some, among whom was Razias, have killed themselves thinking to act from fortitude), yet it is not true fortitude, but rather a weakness of soul unable to bear penal evils, as the Philosopher (Ethic. iii, 7) and Augustine (De Civ. Dei 22,23) declare.
Objection: 1. It would seem that in some cases it is lawful to kill the innocent. The fear of God is never manifested by sin, since on the contrary "the fear of the Lord driveth out sin" (Si 1,27). Now Abraham was commended in that he feared the Lord, since he was willing to slay his innocent son. Therefore one may, without sin, kill an innocent person.
2. Further, among those sins that are committed against one's neighbor, the more grievous seem to be those whereby a more grievous injury is inflicted on the person sinned against. Now to be killed is a greater injury to a sinful than to an innocent person, because the latter, by death, passes forthwith from the unhappiness of this life to the glory of heaven. Since then it is lawful in certain cases to kill a sinful man, much more is it lawful to slay an innocent or a righteous person.
3. Further, what is done in keeping with the order of justice is not a sin. But sometimes a man is forced, according to the order of justice, to slay an innocent person: for instance, when a judge, who is bound to judge according to the evidence, condemns to death a man whom he knows to be innocent but who is convicted by false witnesses; and again the executioner, who in obedience to the judge puts to death the man who has been unjustly sentenced.
On the contrary It is written (Ex 23,7): "The innocent and just person thou shalt not put to death."
I answer that An individual man may be considered in two ways: first, in himself; secondly, in relation to something else. If we consider a man in himself, it is unlawful to kill any man, since in every man though he be sinful, we ought to love the nature which God has made, and which is destroyed by slaying him. Nevertheless, as stated above (Article ) the slaying of a sinner becomes lawful in relation to the common good, which is corrupted by sin. On the other hand the life of righteous men preserves and forwards the common good, since they are the chief part of the community. Therefore it is in no way lawful to slay the innocent.
Reply to Objection: 1. God is Lord of death and life, for by His decree both the sinful and the righteous die. Hence he who at God's command kills an innocent man does not sin, as neither does God Whose behest he executes: indeed his obedience to God's commands is a proof that he fears Him.
2. In weighing the gravity of a sin we must consider the essential rather than the accidental. Wherefore he who kills a just man, sins more grievously than he who slays a sinful man: first, because he injures one whom he should love more, and so acts more in opposition to charity: secondly, because he inflicts an injury on a man who is less deserving of one, and so acts more in opposition to justice: thirdly, because he deprives the community of a greater good: fourthly, because he despises God more, according to Lc 10,16, "He that despiseth you despiseth Me." On the other hand it is accidental to the slaying that the just man whose life is taken be received by God into glory.
3. If the judge knows that man who has been convicted by false witnesses, is innocent he must, like Daniel, examine the witnesses with great care, so as to find a motive for acquitting the innocent: but if he cannot do this he should remit him for judgment by a higher tribunal. If even this is impossible, he does not sin if he pronounce sentence in accordance with the evidence, for it is not he that puts the innocent man to death, but they who stated him to be guilty. He that carries out the sentence of the judge who has condemned an innocent man, if the sentence contains an inexcusable error, he should not obey, else there would be an excuse for the executions of the martyrs: if however it contain no manifest injustice, he does not has no right to discuss the judgment of his superior; nor is it he who slays the innocent man, but the judge whose minister he is.
Objection: 1. It would seem that nobody may lawfully kill a man in self-defense. For Augustine says to Publicola (Ep. xlvii): "I do not agree with the opinion that one may kill a man lest one be killed by him; unless one be a soldier, exercise a public office, so that one does it not for oneself but for others, having the power to do so, provided it be in keeping with one's person." Now he who kills a man in self-defense, kills him lest he be killed by him. Therefore this would seem to be unlawful.
2. Further, he says (De Lib. Arb. i, 5): "How are they free from sin in sight of Divine providence, who are guilty of taking a man's life for the sake of these contemptible things?" Now among contemptible things he reckons "those which men may forfeit unwillingly," as appears from the context (De Lib. Arb. i, 5): and the chief of these is the life of the body. Therefore it is unlawful for any man to take another's life for the sake of the life of his own body.
3. Further, Pope Nicolas [*Nicolas I, Dist. 1, can. De his clericis] says in the Decretals: "Concerning the clerics about whom you have consulted Us, those, namely, who have killed a pagan in self-defense, as to whether, after making amends by repenting, they may return to their former state, or rise to a higher degree; know that in no case is it lawful for them to kill any man under any circumstances whatever." Now clerics and laymen are alike bound to observe the moral precepts. Therefore neither is it lawful for laymen to kill anyone in self-defense.
4. Further, murder is a more grievous sin than fornication or adultery. Now nobody may lawfully commit simple fornication or adultery or any other mortal sin in order to save his own life; since the spiritual life is to be preferred to the life of the body. Therefore no man may lawfully take another's life in self-defense in order to save his own life.
5. Further, if the tree be evil, so is the fruit, according to Mt 7,17. Now self-defense itself seems to be unlawful, according to Rm 12,19: "Not defending [Douay: 'revenging'] yourselves, my dearly beloved." Therefore its result, which is the slaying of a man, is also unlawful.
On the contrary It is written (Ex 22,2): "If a thief be found breaking into a house or undermining it, and be wounded so as to die; he that slew him shall not be guilty of blood." Now it is much more lawful to defend one's life than one's house. Therefore neither is a man guilty of murder if he kill another in defense of his own life.
I answer that Nothing hinders one act from having two effects, only one of which is intended, while the other is beside the intention. Now moral acts take their species according to what is intended, and not according to what is beside the intention, since this is accidental as explained above (Question , Article ; I-II 12,1). Accordingly the act of self-defense may have two effects, one is the saving of one's life, the other is the slaying of the aggressor. Therefore this act, since one's intention is to save one's own life, is not unlawful, seeing that it is natural to everything to keep itself in "being," as far as possible. And yet, though proceeding from a good intention, an act may be rendered unlawful, if it be out of proportion to the end. Wherefore if a man, in self-defense, uses more than necessary violence, it will be unlawful: whereas if he repel force with moderation his defense will be lawful, because according to the jurists [*Cap. Significasti, De Homicid. volunt. vel casual.], "it is lawful to repel force by force, provided one does not exceed the limits of a blameless defense." Nor is it necessary for salvation that a man omit the act of moderate self-defense in order to avoid killing the other man, since one is bound to take more care of one's own life than of another's. But as it is unlawful to take a man's life, except for the public authority acting for the common good, as stated above (Article ), it is not lawful for a man to intend killing a man in self-defense, except for such as have public authority, who while intending to kill a man in self-defense, refer this to the public good, as in the case of a soldier fighting against the foe, and in the minister of the judge struggling with robbers, although even these sin if they be moved by private animosity.
Reply to Objection: 1. The words quoted from Augustine refer to the case when one man intends to kill another to save himself from death. The passage quoted in the Second Objection is to be understood in the same sense. Hence he says pointedly, "for the sake of these things," whereby he indicates the intention.
2. This suffices for the Reply to the Second Objection.
3. Irregularity results from the act though sinless of taking a man's life, as appears in the case of a judge who justly condemns a man to death. For this reason a cleric, though he kill a man in self-defense, is irregular, albeit he intends not to kill him, but to defend himself.
4. The act of fornication or adultery is not necessarily directed to the preservation of one's own life, as is the act whence sometimes results the taking of a man's life.
5. The defense forbidden in this passage is that which comes from revengeful spite. Hence a gloss says: "Not defending yourselves---that is, not striking your enemy back."
Objection: 1. It would seem that one is guilty of murder through killing someone by chance. For we read (Gn 4,23-24) that Lamech slew a man in mistake for a wild beast [*The text of the Bible does not say so, but this was the Jewish traditional commentary on Gn 4,23], and that he was accounted guilty of murder. Therefore one incurs the guilt of murder through killing a man by chance.
2. Further, it is written (Ex 21,22): "If . . . one strike a woman with child, and she miscarry indeed . . . if her death ensue thereupon, he shall render life for life." Yet this may happen without any intention of causing her death. Therefore one is guilty of murder through killing someone by chance.
3. Further, the Decretals [*Dist. 1] contain several canons prescribing penalties for unintentional homicide. Now penalty is not due save for guilt. Therefore he who kills a man by chance, incurs the guilt of murder.
On the contrary Augustine says to Publicola (Ep. xlvii): "When we do a thing for a good and lawful purpose, if thereby we unintentionally cause harm to anyone, it should by no means be imputed to us." Now it sometimes happens by chance that a person is killed as a result of something done for a good purpose. Therefore the person who did it is not accounted guilty.
I answer that According to the Philosopher (Phys. ii, 6) "chance is a cause that acts beside one's intention." Hence chance happenings, strictly speaking, are neither intended nor voluntary. And since every sin is voluntary, according to Augustine (De Vera Relig. xiv) it follows that chance happenings, as such, are not sins.Nevertheless it happens that what is not actually and directly voluntary and intended, is voluntary and intended accidentally, according as that which removes an obstacle is called an accidental cause. Wherefore he who does not remove something whence homicide results whereas he ought to remove it, is in a sense guilty of voluntary homicide. This happens in two ways: first when a man causes another's death through occupying himself with unlawful things which he ought to avoid: secondly, when he does not take sufficient care. Hence, according to jurists, if a man pursue a lawful occupation and take due care, the result being that a person loses his life, he is not guilty of that person's death: whereas if he be occupied with something unlawful, or even with something lawful, but without due care, he does not escape being guilty of murder, if his action results in someone's death.
Reply to Objection: 1. Lamech did not take sufficient care to avoid taking a man's life: and so he was not excused from being guilty of homicide.
2. He that strikes a woman with child does something unlawful: wherefore if there results the death either of the woman or of the animated fetus, he will not be excused from homicide, especially seeing that death is the natural result of such a blow.
3. According to the canons a penalty, is inflicted on those who cause death unintentionally, through doing something unlawful, or failing to take sufficient care.
We must now consider other sinful injuries committed on the person. Under this head there are four points of inquiry:
(1) The mutilation of members;
(4) Whether the sins that consist in inflicting such like injuries are aggravated through being perpetrated on persons connected with others?
Objection: 1. It would seem that in no case can it be lawful to maim anyone. For Damascene says (De Fide Orth. iv, 20) that "sin consists in departing from what is according to nature, towards that which is contrary to nature." Now according to nature it is appointed by God that a man's body should be entire in its members, and it is contrary to nature that it should be deprived of a member. Therefore it seems that it is always a sin to maim a person.
2. Further, as the whole soul is to the whole body, so are the parts of the soul to the parts of the body (De Anima ii, 1). But it is unlawful to deprive a man of his soul by killing him, except by public authority. Therefore neither is it lawful to maim anyone, except perhaps by public authority.
3. Further, the welfare of the soul is to be preferred to the welfare of the body. Now it is not lawful for a man to maim himself for the sake of the soul's welfare: since the council of Nicea [*P. I, sect. 4, can. i] punished those who castrated themselves that they might preserve chastity. Therefore it is not lawful for any other reason to maim a person.
On the contrary It is written (Ex 21,24): "Eye for eye, tooth for tooth, hand for hand, foot for foot."
I answer that Since a member is part of the whole human body, it is for the sake of the whole, as the imperfect for the perfect. Hence a member of the human body is to be disposed of according as it is expedient for the body. Now a member of the human body is of itself useful to the good of the whole body, yet, accidentally it may happen to be hurtful, as when a decayed member is a source of corruption to the whole body. Accordingly so long as a member is healthy and retains its natural disposition, it cannot be cut off without injury to the whole body. But as the whole of man is directed as to his end to the whole of the community of which he is a part, as stated above (Question , Article ; Question , Articles ,5), it may happen that although the removal of a member may be detrimental to the whole body, it may nevertheless be directed to the good of the community, in so far as it is applied to a person as a punishment for the purpose of restraining sin. Hence just as by public authority a person is lawfully deprived of life altogether on account of certain more heinous sins, so is he deprived of a member on account of certain lesser sins. But this is not lawful for a private individual, even with the consent of the owner of the member, because this would involve an injury to the community, to whom the man and all his parts belong. If, however, the member be decayed and therefore a source of corruption to the whole body, then it is lawful with the consent of the owner of the member, to cut away the member for the welfare of the whole body, since each one is entrusted with the care of his own welfare. The same applies if it be done with the consent of the person whose business it is to care for the welfare of the person who has a decayed member: otherwise it is altogether unlawful to maim anyone.
Reply to Objection: 1. Nothing prevents that which is contrary to a particular nature from being in harmony with universal nature: thus death and corruption, in the physical order, are contrary to the particular nature of the thing corrupted, although they are in keeping with universal nature. In like manner to maim anyone, though contrary to the particular nature of the body of the person maimed, is nevertheless in keeping with natural reason in relation to the common good.
2. The life of the entire man is not directed to something belonging to man; on the contrary whatever belongs to man is directed to his life. Hence in no case does it pertain to a person to take anyone's life, except to the public authority to whom is entrusted the procuring of the common good. But the removal of a member can be directed to the good of one man, and consequently in certain cases can pertain to him.
3. A member should not be removed for the sake of the bodily health of the whole, unless otherwise nothing can be done to further the good of the whole. Now it is always possible to further one's spiritual welfare otherwise than by cutting off a member, because sin is always subject to the will: and consequently in no case is it allowable to maim oneself, even to avoid any sin whatever. Hence Chrysostom, in his exposition on Mt 19,12 (Hom. lxii in Matth.), "There are eunuchs who have made themselves eunuchs for the kingdom of heaven," says: "Not by maiming themselves, but by destroying evil thoughts, for a man is accursed who maims himself, since they are murderers who do such things." And further on he says: "Nor is lust tamed thereby, on the contrary it becomes more importunate, for the seed springs in us from other sources, and chiefly from an incontinent purpose and a careless mind: and temptation is curbed not so much by cutting off a member as by curbing one's thoughts."
Objection: 1. It would seem unlawful for parents to strike their children, or masters their slaves. For the Apostle says (Ep 6,4): "You, fathers, provoke not your children to anger"; and further on (Ep 9,6): "And you, masters, do the same thing to your slaves [Vulg.: 'to them'] forbearing threatenings." Now some are provoked to anger by blows, and become more troublesome when threatened. Therefore neither should parents strike their children, nor masters their slaves.
2. Further, the Philosopher says (Ethic. x, 9) that "a father's words are admonitory and not coercive." Now blows are a kind of coercion. Therefore it is unlawful for parents to strike their children.
3. Further, everyone is allowed to impart correction, for this belongs to the spiritual almsdeeds, as stated above (Question , Article ). If, therefore, it is lawful for parents to strike their children for the sake of correction, for the same reason it will be lawful for any person to strike anyone, which is clearly false. Therefore the same conclusion follows.
On the contrary It is written (Pr 13,24): "He that spareth the rod hateth his son," and further on (Pr 23,13): "Withhold not correction from a child, for if thou strike him with the rod, he shall not die. Thou shalt beat him with the rod, and deliver his soul from hell." Again it is written (Si 33,28): "Torture and fetters are for a malicious slave."
I answer that Harm is done a body by striking it, yet not so as when it is maimed: since maiming destroys the body's integrity, while a blow merely affects the sense with pain, wherefore it causes much less harm than cutting off a member. Now it is unlawful to do a person a harm, except by way of punishment in the cause of justice. Again, no man justly punishes another, except one who is subject to his jurisdiction. Therefore it is not lawful for a man to strike another, unless he have some power over the one whom he strikes. And since the child is subject to the power of the parent, and the slave to the power of his master, a parent can lawfully strike his child, and a master his slave that instruction may be enforced by correction.
Reply to Objection: 1. Since anger is a desire for vengeance, it is aroused chiefly when a man deems himself unjustly injured, as the Philosopher states (Rhet. ii). Hence when parents are forbidden to provoke their children to anger, they are not prohibited from striking their children for the purpose of correction, but from inflicting blows on them without moderation. The command that masters should forbear from threatening their slaves may be understood in two ways. First that they should be slow to threaten, and this pertains to the moderation of correction; secondly, that they should not always carry out their threats, that is that they should sometimes by a merciful forgiveness temper the judgment whereby they threatened punishment.
2. The greater power should exercise the greater coercion. Now just as a city is a perfect community, so the governor of a city has perfect coercive power: wherefore he can inflict irreparable punishments such as death and mutilation. On the other hand the father and the master who preside over the family household, which is an imperfect community, have imperfect coercive power, which is exercised by inflicting lesser punishments, for instance by blows, which do not inflict irreparable harm.
3. It is lawful for anyone to impart correction to a willing subject. But to impart it to an unwilling subject belongs to those only who have charge over him. To this pertains chastisement by blows.
Summa Th. II-II EN Qu.64 a.3