Thomas Aquinas, Summa Theologiae

Objection 1: It would seem unlawful to kill men who have sinned. For our Lord in the parable (Mt. 13) forbade the uprooting of the cockle which denotes wicked men according to a gloss. Now whatever is forbidden by God is a sin. Therefore it is a sin to kill a sinner.

Objection 2: Further, human justice is conformed to Divine justice. Now according to Divine justice sinners are kept back for repentance, according to Ezech. 33:11, "I desire not the death of the wicked, but that the wicked turn from his way and live." Therefore it seems altogether unjust to kill sinners.

Objection 3: Further, it is not lawful, for any good end whatever, to do that which is evil in itself, according to Augustine (Contra Mendac. vii) and the Philosopher (Ethic. ii, 6). Now to kill a man is evil in itself, since we are bound to have charity towards all men, and "we wish our friends to live and to exist," according to Ethic. ix, 4. Therefore it is nowise lawful to kill a man who has sinned.

On the contrary, It is written (Ex. 22:18): "Wizards thou shalt not suffer to live"; and (Ps. 100:8): "In the morning I put to death all the wicked of the land."

I answer that, As stated above (Article 1), it is lawful to kill dumb animals, in so far as they are naturally directed to man's use, as the imperfect is directed to the perfect. Now every part is directed to the whole, as imperfect to perfect, wherefore every part is naturally for the sake of the whole. For this reason we observe that if the health of the whole body demands the excision of a member, through its being decayed or infectious to the other members, it will be both praiseworthy and advantageous to have it cut away. Now every individual person is compared to the whole community, as part to whole. Therefore if a man be dangerous and infectious to the community, on account of some sin, it is praiseworthy and advantageous that he be killed in order to safeguard the common good, since "a little leaven corrupteth the whole lump" (1 Cor. 5:6).

Reply to Objection 1: Our Lord commanded them to forbear from uprooting the cockle in order to spare the wheat, i.e. the good. This occurs when the wicked cannot be slain without the good being killed with them, either because the wicked lie hidden among the good, or because they have many followers, so that they cannot be killed without danger to the good, as Augustine says (Contra Parmen. iii, 2). Wherefore our Lord teaches that we should rather allow the wicked to live, and that vengeance is to be delayed until the last judgment, rather than that the good be put to death together with the wicked. When, however, the good incur no danger, but rather are protected and saved by the slaying of the wicked, then the latter may be lawfully put to death.

Reply to Objection 2: According to the order of His wisdom, God sometimes slays sinners forthwith in order to deliver the good, whereas sometimes He allows them time to repent, according as He knows what is expedient for His elect. This also does human justice imitate according to its powers; for it puts to death those who are dangerous to others, while it allows time for repentance to those who sin without grievously harming others.

Reply to Objection 3: By sinning man departs from the order of reason, and consequently falls away from the dignity of his manhood, in so far as he is naturally free, and exists for himself, and he falls into the slavish state of the beasts, by being disposed of according as he is useful to others. This is expressed in Ps. 48:21: "Man, when he was in honor, did not understand; he hath been compared to senseless beasts, and made like to them," and Prov. 11:29: "The fool shall serve the wise." Hence, although it be evil in itself to kill a man so long as he preserve his dignity, yet it may be good to kill a man who has sinned, even as it is to kill a beast. For a bad man is worse than a beast, and is more harmful, as the Philosopher states (Polit. i, 1 and Ethic. vii, 6).

Articulus 2

Argumentum 1

Ad secundum sic proceditur. Videtur quod non sit licitum occidere homines peccatores. Dominus enim, Matth. XIII, in parabola, prohibuit extirpare zizania, qui sunt filii nequam, ut ibidem dicitur.

Sed omne quod est prohibitum a deo est peccatum. Ergo occidere peccatorem est peccatum.

Argumentum 2

Praeterea, iustitia humana conformatur iustitiae divinae.

Sed secundum divinam iustitiam peccatores ad poenitentiam reservantur, secundum illud Ezech. XVIII, nolo mortem peccatoris, sed ut convertatur et vivat.

Ergo videtur esse omnino iniustum quod peccatores occidantur.

Argumentum 3

Praeterea, illud quod est secundum se malum nullo bono fine fieri licet, ut patet per Augustinum, in libro contra mendacium, et per philosophum, in II ethic..

Sed occidere hominem secundum se est malum, quia ad omnes homines debemus caritatem habere; amicos autem volumus vivere et esse, ut dicitur in IX ethic..

Ergo nullo modo licet hominem peccatorem interficere.

Sed Contra

Sed contra est quod dicitur Exod. XXII, maleficos non patieris vivere; et in psalm., in matutino interficiebam omnes peccatores terrae.

Corpus

Respondeo dicendum quod, sicut dictum est, licitum est occidere animalia bruta inquantum ordinantur naturaliter ad hominum usum, sicut imperfectum ordinatur ad perfectum. Omnis autem pars ordinatur ad totum ut imperfectum ad perfectum. Et ideo omnis pars naturaliter est propter totum.

Et propter hoc videmus quod si saluti totius corporis humani expediat praecisio alicuius membri, puta cum est putridum et corruptivum aliorum, laudabiliter et salubriter abscinditur.

Quaelibet autem persona singularis comparatur ad totam communitatem sicut pars ad totum. Et ideo si aliquis homo sit periculosus communitati et corruptivus ipsius propter aliquod peccatum, laudabiliter et salubriter occiditur, ut bonum commune conservetur, modicum enim fermentum totam massam corrumpit, ut dicitur I ad Cor. V.

Ad 1

Ad primum ergo dicendum quod dominus abstinendum mandavit ab eradicatione zizaniorum ut tritico parceretur, idest bonis.

Quod quidem fit quando non possunt occidi mali quin simul occidantur et boni, vel quia latent inter bonos; vel quia habent multos sequaces, ita quod sine bonorum periculo interfici non possunt; ut Augustinus dicit, contra parmen..

Unde dominus docet magis esse sinendum malos vivere, et ultionem reservandum usque ad extremum iudicium, quam quod boni simul occidantur. Quando vero ex occisione malorum non imminet periculum bonis, sed magis tutela et salus, tunc licite possunt mali occidi.

Ad 2

Ad secundum dicendum quod deus, secundum ordinem suae sapientiae, quandoque statim peccatores occidit, ad liberationem bonorum; quandoque autem eis poenitendi tempus concedit; secundum quod ipse novit suis electis expedire. Et hoc etiam humana iustitia imitatur pro posse, illos enim qui sunt perniciosi in alios, occidit; eos vero qui peccant aliis graviter non nocentes, ad poenitentiam reservat.

Ad 3

Ad tertium dicendum quod homo peccando ab ordine rationis recedit, et ideo decidit a dignitate humana, prout scilicet homo est naturaliter liber et propter seipsum existens, et incidit quodammodo in servitutem bestiarum, ut scilicet de ipso ordinetur secundum quod est utile aliis; secundum illud psalm., homo, cum in honore esset, non intellexit, comparatus est iumentis insipientibus, et similis factus est illis; et Prov. XI dicitur, qui stultus est serviet sapienti.

Et ideo quamvis hominem in sua dignitate manentem occidere sit secundum se malum, tamen hominem peccatorem occidere potest esse bonum, sicut occidere bestiam, peior enim est malus homo bestia, et plus nocet, ut philosophus dicit, in I polit. Et in VII ethic..