The War in Ukraine in the Light of Just War Principles

1 Passion and Reason[1]

Pity, fear, and anger are the natural responses to the invasion of Ukraine by Russia. Such passions are naturally intensified by personal ties to Ukraine. I notice that I feel such passions much more strongly in response to this war, than I have felt them in the past towards wars in places to which I had fewer ties. I often visited Ukraine, and have many friends there. Although I am a dual citizen of Austria and the United States, I learned to sing the Ukrainian anthem, She ne vmerla Ukraina[2], at a summer camp in Ukraine before I could sing either the Austrian or the US anthems by heart.

The passions were given us by our Creator to assist us in acting, to help us respond rightly to the goods and evils that we encounter in this life. The passions are like powerful horses pulling the chariot of the soul toward action. But of course, passion is not a sufficient guide to human action. In order to be good guides to action, passion must be informed and guided by reason. The virtuous man “is not passion’s slave.”[3] This does not mean that he lacks passions, but rather that he feels them in the right way, and toward the right objects, so as to preserve the true good apprehended by reason. Reason is like the charioteer who controls the horses of the passions with reigns and whip, so that they draw the chariot in the right direction, and at the right speed, so that it does not capsize at a corner.

There is a danger in human life of being swept along by passion beyond the measure of reason. This is danger is certainly strong in war time. Thus, Sohrab Ahmari, the brilliant post-liberal journalist, warns of us of “trembling emotion, cheap propaganda, wild fantasies, a refusal to dialogue and de-escalate.”[4] Especially in a conflict with Russia, a nation with a huge arsenal of nuclear weapons, the catastrophic effects that could follow from escalating to the point of nuclear war should give us pause. Ahmari is clearly right about this, and those who attack him for being a propagandist for Putin are merely proving his point.

Passions need to be guided by reason. I shall, therefore, lay out some principles for judging the war in a rational manner, the principles of “just war.” I shall then apply them to the situation in Ukraine. I will argue that:

  1. The Russian invasion of Ukraine is unjust.
  2. The Ukrainian defense of their homeland against the invasion is just.
  3. Other countries are justified in giving the Ukrainians indirect aid, but the justice of direct military involvement of a nato country in the war would be more doubtful, given the acute danger of an escalation to the mutually assured destruction of nuclear war.

2 The Principles of Just War

The principles of just war come to us both from Revelation, and from the natural law, written by the Creator into our hearts.

The testimony of Sacred Scripture on war is complex.[5] In the Old Testament, especially in the context of the conquest of the Holy Land, God sometimes commands wars. In the New Testament a great emphasis is laid on renouncing violence. This complexity of the scriptural witness was one of the reasons why the Manichaeans opposed the God of the Old Testament to the God of the Jesus. In his refutation of the Manichaean bishop Faustus, Augustine gave systematic criteria for judging the morality of war. Augustine gives scriptural arguments to show that Jesus was not opposed to war in principle. For example, that Jesus praised a centurion for his faith, but does not tell him to leave his profession (Matthew 8:10).[6] Augustine then gives arguments from natural reason to show that war can sometimes be justified. The two basic criteria for a just war that Augustine mentions are that such a war must be for a just cause, and authorized by the proper authority:

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.[7]

Augustine describes the just cause for a war as the punishment of such evils as violence and lust for power, in other words it is to inflict punishment for the kinds of evil most associated with war:

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.[8]

In other words, for Augustine, a just war is a punitive war.

Augustine’s approach to just war was further developed by the medieval Scholastics (for example, by St Thomas in IIa-IIae Q. 40), and then again by the Baroque Scholastics. Francisco de Vitoria Vitoria (1483-1546), for example, emphasizes the necessity of just war for securing peace and justice:

The purpose of war is the peace and security of the commonwealth. But there can be no security for the commonwealth unless its enemies are prevented from injustice by fear of war. […] Surely it would be impossible for the world to be happy— indeed, it would be the worst of all possible worlds— if tyrants and thieves and robbers were able to injure and oppress the good and the innocent without punishment, whereas the innocent were not allowed to teach the guilty a lesson in return.[9]

He further argues that the only possible just cause for war is “when harm has been inflicted,” either in immediate defense against unjust harm, or in “avenging injuries” after a culpable offense.[10] There are thus two kinds of just war: a defensive war aimed at repelling injustice, and an offensive war, aimed at punishing injustice. Both kinds depend on an actual injustice already committed by the enemy for the justice of their cause.

In the 20th century, a further development of just war theory took place, in the light of modern military technology, which caused such terrible devastation in the World Wars. The great canonist and theologian Alfredo Cardinal Ottaviani (1890-1979) argued that, under modern conditions, a punitive offensive war could never be justified. Defensive war, he argued, could be justified only under extremely limited circumstances:

In practice then, a declaration of war will never be justifiable. A defensive war even should never be undertaken unless a legitimate authority, with whom the decision rests, shall have both certainty of success and very solid proofs that the good accruing to the nation from the war will more than outweigh the untold evils which it will bring on the nation itself, and on the world in general.[11]

Ottaviani’s perspective was adopted by the Second Vatican Council (Gaudium et Spes, §§79-82), and the Catechism of the Catholic Church (§2309).

3 The Russian Cause

The Russian invasion of the Ukraine is unjust, because it is not the response to an actual injustice against Russia on the part of Ukraine. None of the reasons advanced for justifying the Russian invasion are convincing.

The first reason that has been brought forward to justify the invasion was made (almost explicitly) by Vladimir Putin in his now infamous essay “On the Historical Unity of Russians and Ukrainians.” He argued that shared historical and spiritual roots of Russia and Ukraine render their current separation lamentable.[12] This makes it understandable that Putin would want to reunite Russia and Ukraine, but it does not make his doing so by military means just. Putin’s view of Ukrainian history is, moreover, tendentious and one-sided. Yes, Ukraine and Russia have common roots, but their history has often been the history of Russian oppression of Ukraine: the suppression of the Ukrainian language, the persecution of the Ukrainian Greek Catholic Church, and (above all) the killing of millions of Ukrainians in the Holodomor.[13] That history of oppression has in fact been part of the process by which Ukraine has developed into a complete political society, with a sense of its own common good, and its own historical destiny.

A second reason advanced for the justice of the Russian cause is the understandable concern of Russian leaders about Ukraine’s intentions of joining nato. Certainly, it is contrary to Russian interests to have a traditionally hostile military alliance at its borders.[14] But the interests of a great power are not equivalent to a just cause. Ukraine is a complete political society, a societas perfecta, and has the authority to make its own alliances, even if those alliances are contrary to Russian interests. A case can be made that some of the actions of Ukrainian leaders and their friends in the West in the decades since the fall of the Soviet Union were foolish, but such foolishness does not make a Russian invasion just.

A third reason advanced to justify the Russian invasion is that Russia is resisting the imposition of Western immorality on the Donbas. This is the reason alleged by the Patriarch of Moscow. In a sermon on March 6th, the Patriarch claimed that for eight years there have been attempts to destroy the independence of the Donbass, because the separatists of the Donbass fundamentally reject the celebration of the homosexual vice.[15] Now, Patriarch Kirill is not wrong that the sin of Sodom, condemned in both Old and New Testaments, cries to Heaven for vengeance. But where is the evidence to support the claim that the separatists in Donetsk and Luhansk were being attacked by Ukraine on account of their rejection of that sin? While it is true that social norms about unnatural vice in Ukraine have trended in a more permissive direction in recent years, and that that trend has been partly reversed in the separatist republics,[16] no evidence has been produced to show that any Ukrainian attempts at regaining separatist territories were motivated by those trends. Moreover, even if (counterfactually) Russia were defending Donetsk and Luhansk against such trends, this would not justify the invasion of the entire country of Ukraine, which is taking place, and which the Patriarch ignores.

4 The Ukrainian Cause

The Ukrainian cause is just, because they are defending themselves against a grievous injustice. Some have argued that the Ukrainian cause is unjust, because they have no realistic hope of success. They lack what Ottaviani calls “certainty of success” and “proofs that the good accruing to the nation from the war will more than outweigh the untold evils which it will bring on the nation itself, and on the world in general.” But in human affairs absolute certainty can never be found. The Ukrainian authorities, in commanding their troops to defend their homeland, are defending the very existence of their common good, from which their authority derives. They cannot have absolute certainty of success, but they can hope that a vigorous defense will lead Russia to seek a compromise, allowing the Russians to withdraw while saving face. The current negotiations between Ukraine and Russia seem to have been undertaken with precisely such a hope.

5 Foreign Intervention in Ukraine

Since the Ukrainian cause is just, indirect aid on the part of other countries to the Ukrainians—including weapons and other supplies—is justified. The question of whether direct military intervention on the part of other countries in Ukraine would be just is more doubtful. Political authorities in the nato countries have judged that a direct intervention in Ukraine is not justified, given the grave danger of a world war. I believe their judgement is reasonable.

Some have argued that Budapest Memorandum (giving Ukraine the assurance of security in exchange for Ukraine’s signing the Treaty on the Non-Proliferation of Nuclear Weapons) requires the US and the UK to intervene in defense of Ukraine’s territorial integrity. It is certainly a principle of natural law that pacta sunt servanda (pacts are to be kept), however, what the Budapest Memorandum actually requires is that the US and the UK seek UN Security Council Action, which they have done.[17]

In conclusion, it we can only hope and pray that the Ukraine will succeed in its just attempt at repelling the unjust Russian invasion.

[1] This post in based on my contribution to a panel discussion on the war in Ukraine at the Katholische Hochschule ITI in Trumau, organized by the Adenauer Forum. My thanks to John Hennenfent for the invitation. A pdf of this post can be found here.

[2] The first words at the time. The official version has since been modified to put the word “Ukraine” in the genitive: She ne vmerla Ukraini.

[3] Shakespeare, Hamlet, Act III, scene 2.

[4] Sohrab Ahmari, “How Not To Think About Ukraine,” The American Conservative, February 28th, 2022, (accessed March 20th, 2022).

[5] For a helpful overview see: Gerhard Beestermöller, “Krieg,” in: Lexikon für Theologie und Kirche, 3rd ed. (Freiburg: Herder, 1997).

[6] Augustine, Contra Faustum, XXII,13.

[7] Contra Faustum, XXII,75.

[8] Contra Faustum, XXII,74.

[9] Francisco de Vitoria, On the Law of War, Q.1, a.1.

[10] Vitoria, On the Law of War, Q.1, a.3.

[11] Alaphridus Ottaviani, “The Future of Offensive War,” in: Blackfriars 30.354 (1949), pp. 415-420, at p. 419.

[12] Vladimir Vladimirovich Putin, “On the Historical Unity of Russians and Ukrainians,” (accessed March 20th, 2022).

[13] See, for example: Serhii Plokhy, The Gates of Europe: A History of Ukraine (New York: Basic Books, 2015).

[14] See: John J. Mearsheimer, “Why the Ukraine Crisis Is the West’s Fault,” in: Foreign Affairs 93.5 (2014), pp. 1 -12.

[15] Patriarch Kirill of Moscow, “Патриаршая проповедь в Неделю сыропустную после Литургии в Храме Христа Спасителя,” (accessed March 20th, 2022).

[16] See: “Violation of LGBTI Rights in Crimea and Donbass: The Problem of Homophobia in Territories Beyond Ukraine’s Control,” ADC Memorial: The Human Rights Report, 2016, (accessed March 20th, 2022).

[17] See: Belarus, Russian Federation, United Kingdom of Great Britain and Northern Ireland and United States of America Memorandum of Security Assurances in connection with the Republic of Belarus Accession to the Treaty on Non-Proliferation of Nuclear Weapons. Budapest, 5 December 1994, (accessed March 20th, 2022).


15 thoughts on “The War in Ukraine in the Light of Just War Principles

  1. Pingback: The War in Ukraine in the Light of Just War Principles | Sancrucensis – The Old Roman

  2. In a similar way to how Ottovianni said just war theory needed to be re-thought to account for modern warfare, might the idea of the country as societas perfectas need to be rethought in an age of color revolutions etc? Just because a line is drawn around a group of people on a map and person X is put in charge, then removed when person Y proves more amenable to the will of powerful groups, does not make those people into a unified or complete society. I think we understand this instinctively now because both sides try to attack each others legitimacy and divide groups before going to war anyway.


  3. Pingback: TVESDAY EDITION – Big Pulpit

  4. I do not disagree with anything that was written, but as other commentators have written, this topic deserves a more detailed analysis given the fact that we live in an age where countries are conquered not by military might, but by NGOs and soft power. Could it be possible, even theoretically, that a war could be just to defend oneself from such a proliferation of immorality by more subtle means? Is it possible that, and this is forwarded by the pro Russian side, there’s a cause for war in biological weapons which the US is developing in Ukraine? Is it possible that a war is just because there’s a cumulation of smaller reasons for war, even if each on its own is not enough to justify a preemptive strike? Is it possible that it is a just war in what the Russians believe will happen to their nation if Ukraine stays a puppet state of the US State Department?
    As things stand I believe that it is an unjust war and that Russia has invaded primarily to protect its status as a great power. But, various other issues are at play and they do not get the attention they deserve, not only now but for future events as well.


  5. to the point 4:
    Dear Father, I’m not sure if the “current negotiations” can be really named as true or sincere negotiations… Given the fact that the Aggressor continues to attack civilians. And thus I’m not sure if this can be regarded as “hope”, with anticipation of “success”.
    I wish Ukrainians would finally defended themselves, but I’m not sure if it is in all cases feasible…


  6. Pingback: Edward Feser: Unjust war and false masculinity

  7. I believe that a war lie that which is unfolding should unsettle us. I have just heard for a second time the video that Arnold Schwarzenegger produced, his “address to the Russian people.” Doubtless, he did a good job. But there lies the problem: it is too good. It rushes over-hastily to the ostensible moral high ground. It tells us “I am the Strong and Compàssionate One who takes the side of the underdog, so follow me!” A similar thing happened to me while I was listening to Marie Yovanovich on the war. She was the diplomat who testified against Trump in his first impeachment trial. I thought she was believable then, and I felt sorry for her. But now she is telling us that the West is the incarnation of all possible values, and therefore….what? The problem is that we are dealing with sentimental schlock, and the only way to end wars is a hard road of looking for justice and rising above the mediocrities of self-love. Saint Paul VI told us: “If you want peace, work for justice!” Some people don´t like that phrase because it reminds them of progressive Catholicism and Theology of Liberation. I would say that it should remind us of Saint Augustine and the most noble traditions of moral theology and of the Social Doctrine of the Church.

    Liked by 1 person

  8. It´s time to update one´s language about war. There is, I admit, some foundation to the traditional just war doctrine, but the Church has developed its language and its doctrine in the matter and Pope Francis is insisting on the new language, when he says that there is no such thing as a just war. That is clearly and definitively said. But okay, there is this traditional “just war doctrine.” What to do? Scold Pope Francis for his offenses against Traditional Catholic Doctrine? No. Because the Church maintains a carefully thought out teaching about the right to self-defense and Pope Francis has not undermined it. Read what the Compendium of Social Doctrine says about war. It is all there. Francis is absolutely in the line of all the post-conciliar Popes. Mai piu la guerra!

    There remains the morality of difficult situations which cry out for discernment.

    War is an offense against the creator God. So too is adultery. Those who despise Pope Francis from the rigorist camp like insinuating that Amoris Laetitia is an apology for acts of adultery. That is, as I have often insisted, a calumny and a lie. it is a bit like saying that St. Augustine was an apologist for war. He wasn´t. And I think that anyone who calls himself a hardcore Augustininan ought to defend Augustine from such calumnies.


      • Formally war is unjust. It helps to look at Holy Scripture in this matters. The Bible is not about secular matters. I am thinking of Our Lord´s words about settling someone´s problems with a question of inheritances. “This is not my business.” Similarly, Holy Scripture regarding war. Scripture is not about merely historical matters. Scripture is about the Battle that God is fighting and not about the internecine conflicts of humanity. Inversely St. Paul “Our battle is not with the flesh” In other words our battle as men of God is the very battle that God is fighting. It is the battle that the Church Militant is fighting. When we fight against our brothers that saddens the heart of the Father of Mercies. We have gone astray. I invite the readers to look up the history of St. Vladimir, which shows that the Ukraine and Russia are spiritual brothers. This was is so tragic. Is there a right to legitimate self-defense. Of course. Next question?


          • Self-defense is a demand of justice. It is what you do when conscience forbids any other course of action. A country has the same duty to self-defend as the citizen, and the same moral logic. The question is not whether self-defense is justified or not. Self defense is actus humanus. Thus not a mere act of animal passion but very much the opposite. Very praiseworthy. From the point of view of the Common Good..

            And yet Francis is very right in saying that war is never just. That war is evil. That it is a tragedy. That God sheds copious tears.


  9. I disagree with the affirmation that Biblical teaching on war is “complicated.” In the Bible there is only one just war, the war that the Lord of Hosts fights at the head of his people against the powers of darkness. This should not dumbed down to a “complicated” endorsement of merely human enterprises and a feeding trough for the false prophets of whatever foolish form of theocracy is presenting itself currently. and deluding the people of God with half-truths. The Bible´s yes is yes and it´s no is no.


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