The Catholic Perspective Regarding Just War
Table of Contents
War Can Be Just, Sometimes
War can be a horrible thing. It leads to suffering, death and destruction.
But sometimes it is necessary to justly engage in war.
As I wrote in a recent article about self-defense, sometimes it is justified to kill.
However, many times it is not justified to participate in war. So we should know what makes a war just.
In this article, we will go through what the Catholic Church teaches about what makes a war just.
The Catholic Magisterium on Killing in a Just War
What does the magisterium of the Catholic Church say regarding killing in a just war?
First, according to the Catechism of the Council of Trent, written in AD 1566:
In like manner, the soldier is guiltless who, actuated not by motives of ambition or cruelty, but by a pure desire of serving the interests of his country, takes away the life of an enemy in a just war.
Furthermore, there are on record instances of carnage executed by the special command of God. The sons of Levi, who put to death so many thousands in one day, were guilty of no sin; when the slaughter had ceased, they were addressed by Moses in these words: You have consecrated your hands this day to the Lord.
Catechism of the Council of Trent, Fifth Commandment
Second, The Douay Catechism of 1649 says:
Q. Is it not lawful to kill in any cause?
A. Yes, in a just war, or when public justice requires it: “For the magistrate beareth not the sword without cause.” Rom. i. 4. As also in the blameless defence of our own, or our innocent neighbour’s life, against an unjust invader.
The Douay Catechism of 1649 by Henry Tuberville, D.D.
Third, the Baltimore Catechism, written in the late 19th century, states:
Q. 1276. Under what circumstances may human life be lawfully taken?
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2. In a just war, when the safety or rights of the nation require it;
Baltimore Catechism
Fourth, in the Catechism of St. Pius X written in 1908, Pope St. Pius X writes:
3 Q. Are there cases in which it is lawful to kill?
A. It is lawful to kill when fighting in a just war; when carrying out by order of the Supreme Authority a sentence of death in punishment of a crime; and, finally, in cases of necessary and lawful defence of one’s own life against an unjust aggressor.
Catechism of Saint Pius X
There are other Magisterial documents that say the same thing as these.
But the point is that the Church teaches that killing is lawful in a just war.
Father and Doctor St. Augustine on Just War Theory
Church Father and Doctor of the Church St. Augustine was the man who coined the term “just war.”
Around 400 AD, St. Augustine says in Contra Faustum:
The real evils in war are love of violence, revengeful cruelty, fierce and implacable enmity, wild resistance, and the lust of power, and such like; and it is generally to punish these things, when force is required to inflict the punishment, that, in obedience to God or some lawful authority, good men undertake wars, when they find themselves in such a position as regards the conduct of human affairs, that right conduct requires them to act, or to make others act in this way.
Contra Faustum, Book XXII, 74
And:
A great deal depends on the causes for which men undertake wars, and on the authority they have for doing so; for the natural order which seeks the peace of mankind, ordains that the monarch should have the power of undertaking war if he thinks it advisable, and that the soldiers should perform their military duties in behalf of the peace and safety of the community.
Ibid., 75
In a letter written in 418 AD, St. Augustine says:
For, when faith is pledged, it is to be kept even with the enemy against whom the war is waged, how much more with the friend for whom the battle is fought! Peace should be the object of your desire; war should be waged only as a necessity, and waged only that God may by it deliver men from the necessity and preserve them in peace. For peace is not sought in order to the kindling of war, but war is waged in order that peace may be obtained. Therefore, even in waging war, cherish the spirit of a peacemaker, that, by conquering those whom you attack, you may lead them back to the advantages of peace
Letter 189 (A.D. 418)
In The City of God St. Augustine says:
But, say they, the wise man will wage just wars. As if he would not all the rather lament the necessity of just wars, if he remembers that he is a man; for if they were not just he would not wage them, and would therefore be delivered from all wars. For it is the wrongdoing of the opposing party which compels the wise man to wage just wars; and this wrong-doing, even though it gave rise to no war, would still be matter of grief to man because it is man’s wrong-doing.
The City of God (Book XIX) Chapter 7
Later in the book, St. Augustine says:
For even when we wage a just war, our adversaries must be sinning; and every victory, even though gained by wicked men, is a result of the first judgment of God, who humbles the vanquished either for the sake of removing or of punishing their sins.
Ibid., Chapter 15
To summarize: St. Augustine talks about the just causes of war; the need for a legitimate authority to declare war; and the desire to secure peace, to promote good and to punish evil through a just war.
Angelic Doctor St. Thomas Aquinas on Just War Theory
Building on the work of St. Augustine, Angelic Doctor of the Church St. Thomas says:
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 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.”
ST II-II, q. 40, a. 1
To summarize: only the leader of a State has the authority to wage a just war, the authority figure must have a just cause for war, and the intent of the war should be to promote good and/or avoid evil.
Doctor St. Robert Bellarmine on Just War Theory
Regarding just war, Doctor of the Church St. Robert Bellarmine says:
For first it must be shown that war is sometimes lawful for Christians. Secondly, the causes of a just war must be explained.
DE LAICIS, CHAPTER XIV.
For the first proposition of war being sometimes lawful for Christians, St. Robert Bellarmine says:
But we, as the universal Church has always taught, both by word and by deed, say that war is not of its nature unlawful, and that it is lawful not only for Jews but also for Christians to carry on war, provided that those conditions of which we shall treat afterwards are fulfilled.
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Our proposition is proved secondly by the examples of the saints, who waged war; for if war were evil, certainly it would not have been waged by the saints. We read in the Old Testament that Abraham, Moses, Josue, Gideon, Samson, David, Josias, and the Maccabees waged war, thus earning great praise.
…it is evident that war was waged by Constantine, Theodosius, Valentinian, Charlemagne, St. Louis, King of France, St. Maurice with his Theban legion, and by other very saintly Christians, whom the holy bishops never reproved
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Our proposition is proved, thirdly, by the fact that God often aids just wars, which He certainly would not do if war were unlawful : for evils may be permitted, but aid may not also be given in carrying them out.
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Our proposition is proved, fourthly, from reason. Granted that it is lawful for the State to protect its citizens from disturbers of its peace from within, by executing them with various forms of torture, then this is also lawful when there is no other possible way of defending those same citizens from external enemies ; since, in order that the State may be preserved, it is necessary that all enemies, internal as well as external, may be kept off. And since this is the law of nature it is incredible that it should be set aside by the Gospel.
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Lastly, our proposition is proved by the testimony of the Fathers.
Ibid.
To summarize: war is not by definition evil, many Saints have waged war for just reasons, God has commanded and aided wars, the State has a duty to protect its citizens by waging war against any enemies that cause evil, and the Fathers (such as St. Augustine) have all claimed that war can be just.
Regarding the just causes of war, St. Robert Bellarmine says:
Those who treat of such matters usually enumerate four conditions of a just war, lawful authority, a just cause, a good intention, and a suitable method.
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The first condition, then, is lawful authority. For St. Augustine says, “The proper order among human beings, adapted to peace, demands this, that there be authority for undertaking a war and deliberation on the part of the leader, but the soldiers owe to common peace and safety the duty of carrying out orders.” And reason proves this; for private citizens, and those who have a superior, if they are injured by any one, can have recourse to the superior, and seek judgment from him. But if rulers suffer anything at the hands of another ruler, they have no common tribunal before which they may accuse the aggressor, and therefore it is lawful for them to oppose public wrongs by war.
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The second condition is a just cause ; for war cannot be declared for any offense at all, but only for the purpose of warding off an injury. Thus St. Augustine says: “Just wars are usually defined as those in which injuries are avenged, when any nation or city which to be attacked in war has either neglected to satisfy for what has been wickedly done by it, or to return what has been unjustly taken.”
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The third condition is a good intention. For, since the end of war is peace and public tranquility, it is not lawful to undertake war for any other end, hence those sin seriously, whether rulers or soldiers, who begin a war either to injure someone, or to extend their empire, or to show warlike prowess, or for any other cause than the common good, even if lawful authority and a just cause are not lacking. So St. Augustine, in the Epistle to Count Boniface, says, “The will should esteem peace, necessity only should bring about war, that God may deliver us from the necessity of war and preserve us in peace; for peace is not sought in order that war may be waged, but war is waged that peace may be attained…”
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The fourth condition is the suitable manner, which consists chiefly in this, that no innocent person be harmed, as John the Baptist explains, “Do violence to no man ; neither calumniate any man ; and be content with your pay.” By these words he forbids the injuries which soldiers usually inflict on the innocent, either by violence or by trickery, whether to person or to property.
DE LAICIS, CHAPTER XV.
To summarize: a just war requires lawful authority, a just cause, a good intention, and intentional harm of innocents cannot happen in a just war.
If you still want to know more about the Catholic position on just war, then read this article here.