When the ethical topic of war comes up, as it does often enough and with intensity every so often, St. Thomas Aquinas is usually mentioned as a defender of a long-standing Catholic endorsement of the idea of “Just War.” That’s not wrong exactly, but let’s subvert the claim for a bit. I’m a teacher; being ambiguously provocative is basically my whole life.
He does introduce the key article in the Summa (II-II Q40 a1) with an objection stating that wars are always unlawful; as any intro student to Aquinas can tell you, that means that somehow or another wars can be lawful. He does cite St. Augustine’s “Just War” claims quite a bit throughout the articles of the question, always with approval. His respondeo in Q40 lays out three requirements for a war to be lawful which we still use in some form or another even to this day. In some obvious sense, Aquinas clearly believes in “Just War.”
We can see his support for “Just War” at a deeper level as well. He explicitly compares a sovereign waging just war with a sovereign executing just penalties against criminals. In both cases the sovereign wields a power that exists because of the superiority of the common good to private goods. Precisely because the sovereign is the defender and distributor of the common good, he (or they) may lawfully execute criminals and may lawfully wage war. Sovereigns possess powers that private citizens do not and can lawfully do things that are always unlawful for private citizens.
Now let’s pivot.
Aquinas treats war as one of the vices opposed to peace, which in turn is one of the three principle effects of the theological virtue of charity. Charity manifests internally as joy, externally as mercy, and between these two, a hybrid of the internal and external, as peace. As countless commentaries have said before, that immediately puts us in a very different line of argument than your typical modern political treatise which would treat peace under the virtue of justice (assuming we would attach it to any virtue at all, which I doubt).
For Aquinas peace is the concord–unity, harmony, integration–that charity creates within a person whose powers all come to rest in the same object, God. It is also the concord that charity creates between persons who all collectively come to rest in the same object, God. Love, Divine Love, and only Divine Love, makes for peace. This is a beautiful little article in the Summa where Aquinas gives a theoretical account of the unity between love of God and love of neighbor.
If I wanted to provoke in a different direction, I would from here probably argue that seeing peace as an effect of justice is a broken-down, secularized version of the correct theological account of peace. But I want to provoke in a different direction so let’s put a pin in that and return on another day. Back to war.
Aquinas really cares about peace. Like, really really. It is the intersection of an enormous number of lines of thought running throughout the Summa. That’s hardly surprising, given that Aquinas is not a 21st century academic philosopher. He’s a mendicant friar who gave away a life of incredible privilege to devote himself to the evangelical counsels and preaching the gospel and the pursuit of mystical perfection. He lived in a community of poor brothers and had direct charge for their spiritual and intellectual formation. If you thought of him as a Benedictine monk you’d be far, far closer to the truth of the matter than if you think of him as some sort of academic Aristotelian. You’d also annoy Dominicans, which is a fun little bonus.
Part of caring about peace in an Aristotelian key means looking at all its deformities and Aquinas spends quite a bit of time on this. He names six vices opposed to peace, devoting a question to each of discord, contention, schism, war, strife, and sedition. These six are the ways that we, as members of a community or as groups within a community, sin against and subvert the concord of that community. This is the philosophical version of St. Paul’s first letter to the Corinthians, which so vehemently assails factionalism among the Christian faithful and delivers some of the most famous imagery about the unity of the Church anywhere in our tradition.
If you look at the order of the six vices, however, things are a little strange. Some of those vices are proper to individual members of a community and others to groups within the community, but they are not grouped that way. One of the other clear sub-unities is discord-contention-strife, which correspond with an individual acting against concord in desire, in word, and in deed respectively. That’s a direct application of St. Augustine’s definition of sin as a deed, word, or desire contrary to the Divine Law, something Aquinas employs throughout the Summa. But again, the three are not grouped together that way.
And then there is war, which very clearly does not address a way in which we as members of a community act against that community. Or at least, not the way in which Aquinas treats the question. There’s a way in which one could write the war articles that way, but Aquinas very clearly does not do that. So, uh…why’s it on the list?
Let’s take a step back for a moment and think about what Aquinas is trying to do in the Summa here. This is about the formation of Dominican preachers and, indirectly, the faithful who are led and counseled and directed by them. This is a practical work, not an arcane philosophical treatise. What are the real, concrete issues facing quotidian Catholics in the 13th century, or any century for that matter, when it comes to the peace of the community? What advice will Dominican priests need to hand out on a regular basis, what will they preach on when they go into the highways and byways, what will they hear about and address in the confessional? These questions of the Summa are about what we all confess, what we all screw up, what the preachers of the Gospel need to attack and destroy.
War? I’m not saying that wars aren’t awful or that wars are rare. Wars are extremely awful and they are extremely common. I’m saying Aquinas says almost nothing about war that would be of practical use to 99.9% of the people living in his time or any other. It doesn’t fit the paradigm of his treatment of virtues and vices. Ok, maybe I’m overstating a little–he touches on a few things as he goes through the articles and there’s a suggestion of some things based on what he does say. But there is essentially no systematic treatment of what we would later call ius in bello, or right conduct in war. And none whatsoever about how that relates to war’s harmful effects on the community of those going to war, how it acts contrary to the concord of a social whole.
The war question is overwhelmingly preoccupied with what the tradition typically calls ius ad bellum, or the right or the just going toward war–who can wage it, for what purpose, under what conditions. This Summa question, especially the defining Q40 a1, is addressed to sovereigns.
Maybe you can re-purpose his third condition for lawful war, that it be waged with right intention, into a preliminary ius in bello position. And of course the later tradition will have no difficulty elaborating and expanding on the treatment Aquinas gives here so that we have a more systematic treatment of ius ad bellum, ius in bello, and all the endless black-hole questions that go with the ethics of war. And in some sense I suppose it might be of some use to the 99.9% that they know that the wars their sovereigns command them to wage are just or unjust.
But no. No, I claim there’s a more important issue here and it has nothing to do with war itself. I don’t mean to suggest that Aquinas is turning his back on the Augustinian tradition about war. He’s clearly comfortable with sovereigns waging wars under the right conditions. It would be fun to argue that he’s some kind of crypto-abolitionist when it comes to war but again I wish to provoke in a different direction.
I think his war question is (almost) purely a setup question for the next one. He defines war entirely in terms of the sovereign so that he can claim that strife–the sin against concord by deed, by fisticuffs, playground brawling–is a sin. The quotation toward which he builds:
…about this the Gloss on Galatians 5 says that strifes are when out of anger they strike each other. And so strife seems to be a certain private war, because it is done between private persons, not out of some public authority, but rather from a disordered will. And so strife always causes a sin.
(…super illud Gal. V dicit Glossa quod rixae sunt quando ex ira invicem se percutiunt. Et ideo rixa videtur esse quoddam privatum bellum, quod inter privatas personas agitur non ex aliqua publica auctoritate, sed magis ex inordinata voluntate. Et ideo rixa semper importat peccatum.)
ST II-II Q41 a1
The first condition of lawful war is that only the sovereign, the defender and distributor of the common good, may lawfully wage it. Private citizens, never. And so when we wage a kind of private war, not being sovereigns, we sin. We sin mortally, as it turns out. What could be a clearer or more direct action opposed to love of neighbor? Who wages unjust war sins mortally. What war is to the social whole, strife is to the private citizen.
Again, the unity of these questions is peace: all the ways that we may act against the concord of the community to which we belong. War doesn’t do that, but strife clearly does. The discord-contention-strife unity is the crucial one for Aquinas; schism and sedition are group-versions of the same; war…yes, it could in some analogous sense fit in as a group version of strife. But the structure of the argument is the reverse. Once we see what kind of antagonism by deeds is lawful, it becomes trivial to argue that no private citizen may engage in it on pain of mortal sin.
Now that’s something the friars can profitably address all day, every day, to everyone.