Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that it is always sinful to wage war. Because punishment is not inflicted except for sin. Now those who wage war are threatened by Our Lord with punishment, according to Mt. 26:52: "All that take the sword shall perish with the sword." Therefore all wars are unlawful.

Objection 2: Further, whatever is contrary to a Divine precept is a sin. But war is contrary to a Divine precept, for it is written (Mt. 5:39): "But I say to you not to resist evil"; and (Rm. 12:19): "Not revenging yourselves, my dearly beloved, but give place unto wrath." Therefore war is always sinful.

Objection 3: Further, nothing, except sin, is contrary to an act of virtue. But war is contrary to peace. Therefore war is always a sin.

Objection 4: Further, the exercise of a lawful thing is itself lawful, as is evident in scientific exercises. But warlike exercises which take place in tournaments are forbidden by the Church, since those who are slain in these trials are deprived of ecclesiastical burial. Therefore it seems that war is a sin in itself.

On the contrary, Augustine says in a sermon on the son of the centurion : "If the Christian Religion forbade war altogether, those who sought salutary advice in the Gospel would rather have been counselled to cast aside their arms, and to give up soldiering altogether. On the contrary, they were told: 'Do violence to no man . . . and be content with your pay' . If he commanded them to be content with their pay, he did not forbid soldiering."

I answer that, In order for a war to be just, three things are necessary. First, the authority of the sovereign by whose command the war is to be waged. For it is not the business of a private individual to declare war, because he can seek for redress of his rights from the tribunal of his superior. Moreover it is not the business of a private individual to summon together the people, which has to be done in wartime. And as the care of the common weal is committed to those who are in authority, it is their business to watch over the common weal of the city, kingdom or province subject to them. And just as it is lawful for them to have recourse to the sword in defending that common weal against internal disturbances, when they punish evil-doers, according to the words of the Apostle (Rm. 13:4): "He beareth not the sword in vain: for he is God's minister, an avenger to execute wrath upon him that doth evil"; so too, it is their business to have recourse to the sword of war in defending the common weal against external enemies. Hence it is said to those who are in authority (Ps. 81:4): "Rescue the poor: and deliver the needy out of the hand of the sinner"; and for this reason Augustine says (Contra Faust. xxii, 75): "The natural order conducive to peace among mortals demands that the power to declare and counsel war should be in the hands of those who hold the supreme authority."

Secondly, a just cause is required, namely that those who are attacked, should be attacked because they deserve it on account of some fault. Wherefore Augustine says (Questions. in Hept., qu. x, super Jos.): "A just war is wont to be described as one that avenges wrongs, when a nation or state has to be punished, for refusing to make amends for the wrongs inflicted by its subjects, or to restore what it has seized unjustly."

Thirdly, it is necessary that the belligerents should have a rightful intention, so that they intend the advancement of good, or the avoidance of evil. Hence Augustine says (De Verb. Dom. ): "True religion looks upon as peaceful those wars that are waged not for motives of aggrandizement, or cruelty, but with the object of securing peace, of punishing evil-doers, and of uplifting the good." For it may happen that the war is declared by the legitimate authority, and for a just cause, and yet be rendered unlawful through a wicked intention. Hence Augustine says (Contra Faust. xxii, 74): "The passion for inflicting harm, the cruel thirst for vengeance, an unpacific and relentless spirit, the fever of revolt, the lust of power, and such like things, all these are rightly condemned in war."

Reply to Objection 1: As Augustine says (Contra Faust. xxii, 70): "To take the sword is to arm oneself in order to take the life of anyone, without the command or permission of superior or lawful authority." On the other hand, to have recourse to the sword (as a private person) by the authority of the sovereign or judge, or (as a public person) through zeal for justice, and by the authority, so to speak, of God, is not to "take the sword," but to use it as commissioned by another, wherefore it does not deserve punishment. And yet even those who make sinful use of the sword are not always slain with the sword, yet they always perish with their own sword, because, unless they repent, they are punished eternally for their sinful use of the sword.

Reply to Objection 2: Such like precepts, as Augustine observes (De Serm. Dom. in Monte i, 19), should always be borne in readiness of mind, so that we be ready to obey them, and, if necessary, to refrain from resistance or self-defense. Nevertheless it is necessary sometimes for a man to act otherwise for the common good, or for the good of those with whom he is fighting. Hence Augustine says (Ep. ad Marcellin. cxxxviii): "Those whom we have to punish with a kindly severity, it is necessary to handle in many ways against their will. For when we are stripping a man of the lawlessness of sin, it is good for him to be vanquished, since nothing is more hopeless than the happiness of sinners, whence arises a guilty impunity, and an evil will, like an internal enemy."

Reply to Objection 3: Those who wage war justly aim at peace, and so they are not opposed to peace, except to the evil peace, which Our Lord "came not to send upon earth" (Mt. 10:34). Hence Augustine says (Ep. ad Bonif. clxxxix): "We do not seek peace in order to be at war, but we go to war that we may have peace. Be peaceful, therefore, in warring, so that you may vanquish those whom you war against, and bring them to the prosperity of peace."

Reply to Objection 4: Manly exercises in warlike feats of arms are not all forbidden, but those which are inordinate and perilous, and end in slaying or plundering. In olden times warlike exercises presented no such danger, and hence they were called "exercises of arms" or "bloodless wars," as Jerome states in an epistle .

Articulus 1

Argumentum 1

Ad primum sic proceditur. Videtur quod bellare semper sit peccatum. Poena enim non infligitur nisi pro peccato.

Sed bellantibus a domino indicitur poena, secundum illud Matth. XXVI, omnis qui acceperit gladium gladio peribit.

Ergo omne bellum est illicitum.

Argumentum 2

Praeterea, quidquid contrariatur divino praecepto est peccatum.

Sed bellare contrariatur divino praecepto, dicitur enim Matth. V, ego dico vobis non resistere malo; et Rom. XII dicitur, non vos defendentes, carissimi, sed date locum irae.

Ergo bellare semper est peccatum.

Argumentum 3

Praeterea, nihil contrariatur actui virtutis nisi peccatum.

Sed bellum contrariatur paci.

Ergo bellum semper est peccatum.

Argumentum 4

Praeterea, omne exercitium ad rem licitam licitum est, sicut patet in exercitiis scientiarum. Sed exercitia bellorum, quae fiunt in torneamentis, prohibentur ab ecclesia, quia morientes in huiusmodi tyrociniis ecclesiastica sepultura privantur.

Ergo bellum videtur esse simpliciter peccatum.

Sed Contra

Sed contra est quod Augustinus dicit, in sermone de puero centurionis, si christiana disciplina omnino bella culparet, hoc potius consilium salutis petentibus in evangelio daretur, ut abiicerent arma, seque militiae omnino subtraherent. Dictum est autem eis, neminem concutiatis; estote contenti stipendiis vestris. Quibus proprium stipendium sufficere praecepit, militare non prohibuit.

Corpus

Respondeo dicendum quod ad hoc quod aliquod bellum sit iustum, tria requiruntur. Primo quidem, auctoritas principis, cuius mandato bellum est gerendum. Non enim pertinet ad personam privatam bellum movere, quia potest ius suum in iudicio superioris prosequi. Similiter etiam quia convocare multitudinem, quod in bellis oportet fieri, non pertinet ad privatam personam.

Cum autem cura reipublicae commissa sit principibus, ad eos pertinet rem publicam civitatis vel regni seu provinciae sibi subditae tueri. Et sicut licite defendunt eam materiali gladio contra interiores quidem perturbatores, dum malefactores puniunt, secundum illud apostoli, ad Rom. XIII, non sine causa gladium portat, minister enim dei est, vindex in iram ei qui male agit; ita etiam gladio bellico ad eos pertinet rempublicam tueri ab exterioribus hostibus.

Unde et principibus dicitur in psalm., eripite pauperem, et egenum de manu peccatoris liberate.

Unde Augustinus dicit, contra faust., ordo naturalis, mortalium paci accommodatus, hoc poscit, ut suscipiendi belli auctoritas atque consilium penes principes sit.

Secundo, requiritur causa iusta, ut scilicet illi qui impugnantur propter aliquam culpam impugnationem mereantur.

Unde Augustinus dicit, in libro quaest., iusta bella solent definiri quae ulciscuntur iniurias, si gens vel civitas plectenda est quae vel vindicare neglexerit quod a suis improbe factum est, vel reddere quod per iniuriam ablatum est.

Tertio, requiritur ut sit intentio bellantium recta, qua scilicet intenditur vel ut bonum promoveatur, vel ut malum vitetur.

Unde Augustinus, in libro de verbis dom., apud veros dei cultores etiam illa bella pacata sunt quae non cupiditate aut crudelitate, sed pacis studio geruntur, ut mali coerceantur et boni subleventur.

Potest autem contingere quod etiam si sit legitima auctoritas indicentis bellum et causa iusta, nihilominus propter pravam intentionem bellum reddatur illicitum.

Dicit enim Augustinus, in libro contra faust., nocendi cupiditas, ulciscendi crudelitas, implacatus et implacabilis animus, feritas rebellandi, libido dominandi, et si qua sunt similia, haec sunt quae in bellis iure culpantur.

Ad 1

Ad primum ergo dicendum quod, sicut Augustinus dicit, in II Lib. Contra manich., ille accipit gladium qui, nulla superiori aut legitima potestate aut iubente vel concedente, in sanguinem alicuius armatur.

Qui vero ex auctoritate principis vel iudicis, si sit persona privata; vel ex zelo iustitiae, quasi ex auctoritate dei, si sit persona publica, gladio utitur, non ipse accipit gladium, sed ab alio sibi commisso utitur. Unde ei poena non debetur. Nec tamen illi etiam qui cum peccato gladio utuntur semper gladio occiduntur. Sed ipso suo gladio semper pereunt, quia pro peccato gladii aeternaliter puniuntur, nisi poeniteant.

Ad 2

Ad secundum dicendum quod huiusmodi praecepta, sicut Augustinus dicit, in libro de serm. Dom. In monte, semper sunt servanda in praeparatione animi, ut scilicet semper homo sit paratus non resistere vel non se defendere si opus fuerit. Sed quandoque est aliter agendum propter commune bonum, et etiam illorum cum quibus pugnatur.

Unde Augustinus dicit, in Epist. Ad Marcellinum, agenda sunt multa etiam cum invitis benigna quadam asperitate plectendis. Nam cui licentia iniquitatis eripitur, utiliter vincitur, quoniam nihil est infelicius felicitate peccantium, qua poenalis nutritur impunitas, et mala voluntas, velut hostis interior, roboratur.

Ad 3

Ad tertium dicendum quod etiam illi qui iusta bella gerunt pacem intendunt. Et ita paci non contrariantur nisi malae, quam dominus non venit mittere in terram, ut dicitur Matth. X.

Unde Augustinus dicit, ad bonifacium, non quaeritur pax ut bellum exerceatur, sed bellum geritur ut pax acquiratur. Esto ergo bellando pacificus, ut eos quos expugnas ad pacis utilitatem vincendo perducas.

Ad 4

Ad quartum dicendum quod exercitia hominum ad res bellicas non sunt universaliter prohibita, sed inordinata exercitia et periculosa, ex quibus occisiones et depraedationes proveniunt.

Apud antiquos autem exercitationes ad bella sine huiusmodi periculis erant, et ideo vocabantur meditationes armorum, vel bella sine sanguine, ut per Hieronymum patet, in quadam epistola.