Christians and War

by St. Thomas Aquinas


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 Mathew: "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: "But I say to you not to resist evil"; and "Not revenging yourselves on others... but await God's wrath to punish them." 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 counseled 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. 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 commonweal is committed to those who are in authority, it is their business to watch over the commonweal 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 commonweal against internal disturbances, when they punish evil-doers, according to the words of the Apostle: "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 commonweal against external enemies. Hence it is said to those who are in authority: "Rescue the poor: and deliver the needy out of the hand of the sinner"; and for this reason Augustine says: "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: "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: "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: "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: "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, 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: "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". Hence Augustine says: "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 that 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.


Objection 1: It would seem lawful for clerics and bishops to fight. For, as stated above, wars are lawful and just in so far as they protect the poor and the entire common weal from suffering at the hands of the foe. Now this seems to be above all the duty of prelates, for Gregory says: "The wolf comes upon the sheep, when any unjust and rapacious man oppresses those who are faithful and humble. But he who was thought to be the shepherd, and was not, leaves the sheep and flies, for he fears lest the wolf hurt him, and dares not stand up against his injustice." Therefore it is lawful for prelates and clerics to fight.

Objection 2: Further, Pope Leo IV writes: "As untoward tidings had frequently come from the Saracen side, some said that the Saracens would come to the port of Rome secretly and covertly; for which reason we commanded our people to gather together, and ordered them to go down to the seashore." Therefore it is lawful for bishops to fight.

Objection 3: Further, apparently, it comes to the same whether a man does a thing himself, or consents to its being done by another...: "They who do such things, are worthy of death, and not only they that do them, but they also that consent to them that do them." Now those, above all, seem to consent to a thing, who induce others to do it. But it is lawful for bishops and clerics to induce others to fight: for it is written that Charles went to war with the Lombards at the instance and entreaty of Adrian, bishop of Rome. Therefore they also are allowed to fight.

Objection 4: Further, whatever is right and meritorious in itself, is lawful for prelates and clerics. Now it is sometimes right and meritorious to make war, for it is written that if "a man die for the true faith, or to save his country, or in defense of Christians, God will give him a heavenly reward." Therefore it is lawful for bishops and clerics to fight.

On the contrary, It was said to Peter as representing bishops and clerics: "Put up again thy sword into its place." Therefore it is not lawful for them to fight.

I answer that, Several things are requisite for the good of a human society: and a number of things are done better and quicker by a number of persons than by one, as the Philosopher observes, while certain occupations are so inconsistent with one another, that they cannot be fittingly exercised at the same time; wherefore those who are deputed to important duties are forbidden to occupy themselves with things of small importance. Thus according to human laws, soldiers who are deputed to warlike pursuits are forbidden to engage in commerce.

Now warlike pursuits are altogether incompatible with the duties of a bishop and a cleric, for two reasons. The first reason is a general one, because...warlike pursuits are full of unrest, so that they hinder the mind very much from the contemplation of Divine things, the praise of God, and prayers for the people, which belong to the duties of a cleric. Wherefore just as commercial enterprises are forbidden to clerics, because they unsettle the mind too much, so too are warlike pursuits...: "No man being a soldier to God, entangles himself with secular business." The second reason is a special one... all the clerical Orders are directed to the ministry of the altar, on which the Passion of Christ is represented sacramentally...: "As often as you shall eat this bread, and drink the chalice, you shall show the death of the Lord, until He come." Wherefore it is unbecoming for them to slay or shed blood, and it is more fitting that they should be ready to shed their own blood for Christ, so as to imitate in deed what they portray in their ministry. For this reason it has been decreed that those who shed blood, even without sin, become contrary to the law specific to the clerical state. Now no man who has a certain duty to perform, can lawfully do that which renders him unfit for that duty. Wherefore it is altogether unlawful for clerics to fight, because war is directed to the shedding of blood.

Reply to Objection 1: Prelates ought to withstand not only the wolf who brings spiritual death upon the flock, but also the pillager and the oppressor who work bodily harm; not, however, by having recourse themselves to material arms, but by means of spiritual weapons, according to the saying of the Apostle: "The weapons of our warfare are not carnal, but mighty through God." Such are salutary warnings, devout prayers, and, for those who are obstinate, the sentence of excommunication.

Reply to Objection 2: Prelates and clerics may, by the authority of their superiors, take part in wars, not indeed by taking up arms themselves, but by affording spiritual help to those who fight justly, by exhorting and absolving them, and by other like spiritual helps. Thus in the Old Testament the priests were commanded to sound the sacred trumpets in the battle. It was for this purpose that bishops or clerics were first allowed to go to the front: and it is an abuse of this permission, if any of them take up arms themselves.

Reply to Objection 3: As stated above every power, art or virtue that regards the end, has to dispose that which is directed to the end. Now, among the faithful, carnal wars should be considered as having for their end the Divine spiritual good to which clerics are deputed. Wherefore it is the duty of clerics to dispose and counsel other men to engage in just wars. For they are forbidden to take up arms, not as though it were a sin, but because such an occupation is unbecoming their personality.

Reply to Objection 4: Although it is meritorious to wage a just war, nevertheless it is rendered unlawful for clerics, by reason of their being deputed to works more meritorious still. Thus the marriage act may be meritorious; and yet it becomes reprehensible in those who have vowed virginity, because they are bound to a yet greater good.


Objection 1: It would seem that it is unlawful to lay ambushes in war. For it is written: "Thou shalt follow justly after that which is just." But ambushes, since they are a kind of deception, seem to pertain to injustice. Therefore it is unlawful to lay ambushes even in a just war.

Objection 2: Further, ambushes and deception seem to be opposed to faithfulness even as lies are. But since we are bound to keep faith with all men, it is wrong to lie to anyone, as Augustine states. Therefore, as one is bound to keep faith with one's enemy, as Augustine states, it seems that it is unlawful to lay ambushes for one's enemies.

Objection 3: Further, it is written: "Whatsoever you would that men should do to you, do you also to them": and we ought to observe this in all our dealings with our neighbor. Now our enemy is our neighbor. Therefore, since no man wishes ambushes or deceptions to be prepared for himself, it seems that no one ought to carry on war by laying ambushes.

On the contrary, Augustine says: "Provided the war be just, it is no concern of justice whether it be carried on openly or by ambushes": and he proves this by the authority of the Lord, Who commanded Joshua to lay ambushes for the city of Hai.

I answer that, the object of laying ambushes is in order to deceive the enemy. Now a man may be deceived by another's word or deed in two ways. First, through being told something false, or through the breaking of a promise, and this is always unlawful. No one ought to deceive the enemy in this way, for there are certain "rights of war and covenants, which ought to be observed even among enemies," as Ambrose states.

Secondly, a man may be deceived by what we say or do, because we do not declare our purpose or meaning to him. Now we are not always bound to do this, since even in the Sacred Doctrine many things have to be concealed, especially from unbelievers, lest they deride it, according to Matthew: "Give not that which is holy, to dogs." Wherefore much more ought the plan of campaign to be hidden from the enemy. For this reason among other things that a soldier has to learn the art of concealing his purpose lest it come to the enemy's knowledge, as stated in the Book on Strategy by Frontinus. Such like concealment is what is meant by an ambush which may be lawfully employed in a just war.

Nor can these ambushes be properly called deceptions, nor are they contrary to justice or to a well-ordered will. For a man would have an inordinate will if he were unwilling that others should hide anything from him. This suffices for the Replies to the Objections.


Objection 1: It would seem unlawful to fight on holy days. For holy days are instituted that we may give our time to the things of God. Hence they are included in the keeping of the Sabbath prescribed in Exodus: for "sabbath" is interpreted "rest." But wars are full of unrest. Therefore by no means is it lawful to fight on holy days.

Objection 2: Further, certain persons are reproached because on fast-days they exacted what was owing to them, were guilty of strife, and of smiting with the fist. Much more, therefore, is it unlawful to fight on holy days.

Objection 3: Further, no ill deed should be done to avoid temporal harm. But fighting on a holy day seems in itself to be an ill deed. Therefore no one should fight on a holy day even through the need of avoiding temporal harm.

On the contrary, It is written: The Jews rightly determined . . . saying: "Whosoever shall come up against us to fight on the Sabbath-day, we will fight against him."

I answer that, the observance of holy days is no hindrance to those things which are ordained to man's safety, even that of his body. Hence Our Lord argued with the Jews, saying: "Are you angry at Me because I have healed the whole man on the Sabbath-day?" Hence physicians may lawfully attend to their patients on holy days. Now there is much more reason for safeguarding the commonweal (whereby many are saved from being slain, and innumerable evils both temporal and spiritual prevented), than the bodily safety of an individual. Therefore, for the purpose of safeguarding the commonweal of the faithful, it is lawful to carry on a war on holy days, provided there be need for doing so: because it would be to tempt God, if notwithstanding such a need, one were to choose to refrain from fighting.

However, as soon as the need ceases, it is no longer lawful to fight on a holy day, for the reasons given. This suffices for the Replies to the Objections.


Objection 1. It seems that fortitude is not properly about dangers of death in battle. For martyrs above all are commended for their fortitude. But martyrs are not commended in connection with battle. Therefore fortitude is not properly about dangers of death in battle.

Objection 2. Further, Ambrose says that "fortitude is applicable both to warlike and to civil matters": and Tully, under the heading, "That it pertains to fortitude to excel in battle rather than in civil life," says: "Although not a few think that the business of war is of greater importance than the affairs of civil life, this opinion must be qualified: and if we wish to judge the matter truly, there are many things in civil life that are more important and more glorious than those connected with war." Now greater fortitude is about greater things. Therefore fortitude is not properly concerned with death in battle.

Objection 3. Further, war is directed to the preservation of a country's temporal peace: for Augustine says that "wars are waged in order to insure peace." Now it does not seem that one ought to expose oneself to the danger of death for the temporal peace of one's country, since this same peace is the occasion of much license in morals. Therefore it seems that the virtue of fortitude is not about the danger of death in battle.

On the contrary, the Philosopher says that fortitude is chiefly about death in battle.

I answer that, as stated above, fortitude strengthens a man's mind against the greatest danger, which is that of death. Now fortitude is a virtue; and it is essential to virtue ever to tend to good; wherefore it is in order to pursue some good that man does not fly from the danger of death. But the dangers of death arising out of sickness, storms at sea, attacks from robbers, and the like, do not seem to come on a man through his pursuing some good. On the other hand, the dangers of death which occur in battle come to man directly on account of some good, because, to wit, he is defending the common good by a just fight.

Now a just fight is of two kinds. First, there is the general combat, for instance, of those who fight in battle; secondly, there is the private combat, as when a judge or even private individual does not refrain from giving a just judgment through fear of the impending sword, or any other danger though it threaten death. Hence it belongs to fortitude to strengthen the mind against dangers of death, not only such as arise in a general battle, but also such as occur in private combat, which may be called by the general name of battle. Accordingly it must be granted that fortitude is properly about dangers of death occurring in battle.

Moreover, a brave man behaves well in face of danger of any other kind of death; especially since man may be in danger of any kind of death on account of virtue: thus may a man not fail to attend on a sick friend through fear of deadly infection, or not refuse to undertake a journey with some godly object in view through fear of shipwreck or robbers.

Reply to Objection 1. Martyrs face the fight that is waged against their own person, and this for the sake of the sovereign good which is God; wherefore their fortitude is praised above all. Nor is it outside the genus of fortitude that regards warlike actions, for which reason they are said to have been valiant in battle.

Reply to Objection 2
. Personal and civil business is differentiated from the business of war that regards general wars. However, personal and civil affairs admit of dangers of death arising out of certain conflicts which are private wars, and so with regard to these also there may be fortitude properly so called.

Reply to Objection 3. The peace of the state is good in itself, nor does it become evil because certain persons make evil use of it. For there are many others who make good use of it; and many evils prevented by it, such as murders and sacrileges, are much greater than those which are occasioned by it, and which belong chiefly to the sins of the flesh.


Objection 1. It would seem that we ought not to love more those who are more closely united to us by ties of blood. For it is written (Prov. 18:24): "A man amiable in society, shall be more friendly than a brother." Again, Valerius Maximus says: "The ties of friendship are most strong and in no way yield to the ties of blood." Moreover it is quite certain and undeniable, that as to the latter, the lot of birth is fortuitous, whereas we contract the former by an untrammelled will, and a solid pledge. Therefore we ought not to love more than others those who are united to us by ties of blood.

Objection 2
. Further, Ambrose says: "I love not less you whom I have begotten in the Gospel, than if I had begotten you in wedlock, for nature is no more eager to love than grace." Surely we ought to love those whom we expect to be with us for ever more than those who will be with us only in this world. Therefore we should not love our kindred more than those who are otherwise connected with us.

Objection 3. Further, "Love is proved by deeds," as Gregory states. Now we are bound to do acts of love to others than our kindred: thus in the army a man must obey his officer rather than his father. Therefore we are not bound to love our kindred most of all.

On the contrary, The commandments of the decalogue contain a special precept about the honor due to our parents. Therefore we ought to love more specially those who are united to us by ties of blood.

I answer that
, As stated above, we ought out of charity to love those who are more closely united to us more, both because our love for them is more intense, and because there are more reasons for loving them. Now intensity of love arises from the union of lover and beloved: and therefore we should measure the love of different persons according to the different kinds of union, so that a man is more loved in matters touching that particular union in respect of which he is loved. And, again, in comparing love to love we should compare one union with another.

Accordingly we must say that friendship among blood relations is based upon their connection by natural origin, the friendship of fellow-citizens on their civic fellowship, and the friendship of those who are fighting side by side on the comradeship of battle. Wherefore in matters pertaining to nature we should love our kindred most, in matters concerning relations between citizens, we should prefer our fellow-citizens, and on the battlefield our fellow-soldiers. Hence the Philosopher says that "it is our duty to render to each class of people such respect as is natural and appropriate. This is in fact the principle upon which we seem to act, for we invite our relations to a wedding . . . It would seem to be a special duty to afford our parents the means of living . . . and to honor them."

The same applies to other kinds of friendship.

If however we compare union with union, it is evident that the union arising from natural origin is prior to, and more stable than, all others, because it is something affecting the very substance, whereas other unions supervene and may cease altogether. Therefore the friendship of kindred is more stable, while other friendships may be stronger in respect of that which is proper to each of them.

Reply to Objection 1. In as much as the friendship of comrades originates through their own choice, love of this kind takes precedence of the love of kindred in matters where we are free to do as we choose, for instance in matters of action. Yet the friendship of kindred is more stable, since it is more natural, and preponderates over others in matters touching nature: consequently we are more beholden to them in the providing of necessaries.

Reply to Objection 2. Ambrose is speaking of love with regard to favors respecting the fellowship of grace, namely, moral instruction. For in this matter, a man ought to provide for his spiritual children whom he has begotten spiritually, more than for the sons of his body, whom he is bound to support in bodily sustenance.

Reply to Objection 3. The fact that in the battle a man obeys his officer rather than his father proves, that he loves his father less, not in an absolute sense but simply relatively, i.e. as regards the love which is based on fellowship in battle. [Selections from St. Thomas Aquinas, Summa Theologica.]

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