A decade ago, when David Armitage began working on his new book, Civil Wars: A History in Ideas, published this week by Knopf, he had no idea how relevant the subject would become. These days, it’s hard to avoid concluding that American society is tearing itself apart. Several observations and arguments in the book can be harrowing to read—that the nations mostly likely to devolve into civil wars are those that have suffered such conflicts before; that civil wars are most likely when the government is divided against itself; that politics is civil war by other means. Civil Wars ranges over more than two millennia of history, law, and philosophy, but it feels as urgent as the latest shock, as fresh as tomorrow’s news.

I recently spoke with Armitage about his book. The conversation has been lightly edited.

—Richard Kreitner

You write in the book that you began working on it after you “found the past rhyming with the present.” What were some of those rhymes that you saw, and what questions were you trying to answer?

I was on academic leave in that period when the Second Gulf War was at the height of its violence, around December 2006 and early 2007. I was in residence during that period at Huntington Library in Southern California, which holds the papers of Francis Lieber, whose name was popping up in the media discussion about Iraq around the same time. Even though he was a 19th-century Prussian, he became newly relevant because he produced the first codification of laws of war and debates about treatment of enemy combatants, subjects very much at issue at the time I was encountering his work.

Among his papers at the Huntington Library was correspondence with his boss, Henry Hallek, a Union general, about the code and, in particular, about the absence of discussion of civil war in it—a strange omission for a code of the laws of war in the midst of the what became known as the US Civil War. There was no legal definition available to him, so he had to describe and define civil war in legal terms that exactly coincided with highly ideological debates in the media and in Congress about whether or not the violence in Iraq should be considered a civil war, or instead a rebellion or an insurgency or an insurrection. As I was reading this mid-19th-century correspondence I was hearing in the news and in the papers about how hard it still was to define a civil war. That’s one of those moments when, as Mark Twain said, history rhymes. I realized that these were two data points—one from the 1860s, and one from the 2000s—which were part of a longer history of civil war that needed reconstructing.

This book is a story of paradox, from the first page to the last. Can you explain why the very idea of “civil war,” beginning with the Romans, is a bundle of contradiction?

The Romans were the first to call this kind of conflict “civil wars.” The literal term “civil” comes from the Latin word cives, which means citizens. Romans named wars after the enemy they were fighting, so in this particular case, to call a war “civil” recognized that it was fought against a particularly familiar, even familial, enemy within Rome itself. Why was this paradoxical? Because the Roman definition of war hinged on it being fought for a just cause against an external enemy. To have a war against fellow citizens was to have a war that was not any kind of recognizable form of warfare at all. This was paradoxical, perhaps even oxymoronic, and it accounts for the fact that for several decades after the term was first recorded it was used very sparingly. “Civil war” is almost like the war that cannot speak its name. Romans didn’t want to recognize that they had descended to this destructive form of enmity against their own citizens. Even Julius Caesar, Rome’s most famous civil warrior, doesn’t use the term “civil war” in the context of his own history, an indication of his reluctance to deploy this deeply unsettling description of contention among the Romans who themselves invented it.

One of the questions that you say has been asked about civil wars across the centuries and millennia is whether there can be such a thing as a commonwealth designed to be immune to civil war. I was interested in how this connects with Foucault’s point that politics is a continuation of civil war. When we put these things together it seems difficult to imagine what such a commonwealth would be. Is the very desire to escape the possibility of civil war a form of politics, and who—what forces, what interests—in society does such an aspiration serve?

If we go to the same abstract but important, all-encompassing level that Foucault went to, we may say broadly that politics, ancient and modern, is the means of managing fundamental differences over irreconcilable values without coming to the point of actual open violence. That’s a very broad definition—politics is the agonistic form of struggle which goes to the potential border of open violence but allows us to frame our contention over differences without actually crossing it. Foucault was of course alluding to Clausewitz’s famous phrase that war is politics by other means. In our contemporary moment in the United States and in Europe, as well as other parts of the world, what we’re seeing is the fracturing of that conception of politics, the incursion of violent language into the civic discourse, the emergence of actual interpersonal violence in the public sphere. Increasingly, democratic politics does in fact look like civil war by other means. Whether we breach that boundary, or cross the Rubicon, as Caesar did, remains to be seen. The linguistic temperature of contemporary politics has risen so high that civil war outside the bounds of politics is increasingly conceivable—and that is quite concerning.

I did not intend to write a handbook for our times, but as someone attuned to the long history of civil war I cannot but be alarmed by the contemporary dissolution of the boundaries between politics and civil contention or even civil war that we’re seeing around the world.

“Forgetting is the best defense against civil war.” So you quote the Roman historian Titus Labienus. Would you say then that the very act of Civil War historiography, in the American context at least, is a political act—something that is destined to tear the country apart yet again?

It may be a political act but it’s not necessarily destined to tear the country apart. What has been reaffirmed throughout history is that memory of civil war is explosive in ways that memory of other kinds of warfare is not. Civil wars leave wounds that can’t be healed, divisions that seem to be closed but will open again. The Romans often used the metaphor of volcanos, which fall quiet and re-erupt. Contemporary political scientists have discovered that societies are most likely to have civil wars if they’ve had one before. The rawness of history and memory within communities and families means that it’s always easy to touch off high passions about old conflicts. Think, with regard to the United States, of the recent controversies about flying the Confederate flag. Those issues have deep charges within contemporary racial politics, but the very fact that they’re playing off divisions of 150 years ago, and that they map onto those political and ethnic divisions even today, shows that the wounds of the Civil War have not entirely closed.

I was quite struck, reading this book during that second tumultuous weekend of Trump’s presidency, with the acting attorney general publicly refusing to defend the immigration order and then being fired, a thousand foreign-service authors protesting the ban, by your summary of Hobbes’s account of civil war—that it arises “when the public authority itself had become divided.” How compelling do you find that definition, and do you think we might be seeing elements of such a division emerging in the United States today?

Hobbes’s intent was to reaffirm his own conception of sovereignty as unitary, undivided, and indivisible, which was absolutely central to his redefinition of sovereignty against many predecessors’ accounts, going back to the 16th century. He was writing amidst the English Civil Wars of the 1640s, which he attributed to doubts over the location of sovereignty, whether it was with the monarch himself or Parliament or some negotiation between them. Uncertainty on that question, he believed, had plunged his country into warfare. So we must be aware of the ideological and political context of his arguments.

The greater concern in the United States today is about preserving the separation of powers and the system of checks and balances that are central to the American system of government, and which, incidentally, would have been horrifying to Hobbes. The blurring of those boundaries is what’s most worrying—not just the expedient kowtowing of the Republican majority in Congress to the wishes of an insurgent presidency, but the blurring of lines seen in the employment of congressional staff to help draft executive orders, which was apparently kept secret through non-disclosure agreements. That represents a blatant erasure of the boundaries between the two branches. Then there’s the judicial orders being overruled or ignored by border agents, a very worrying sign of the future independence of the judiciary and its ability to enforce the rule of law. The real concern is the unbalancing of the checks and balances that are in place to protect against overweening power. If anything, it’s Trump who is the Hobbesian, who wants to centralize authority within the White House. The signs of push-back from the other branches of government have not been encouraging, to put it mildly.

A recurring theme of the book is that the contours of political community emerge most starkly in the very moment of that community’s collapse into disorder and civil war. This seems connected to this question that quietly appears and reappears in the text as to whether civil war is necessarily always and everywhere such a bad thing. I believe it’s Chateaubriand who you quote rather emphatically insisting that’s not quite the case. Can you unpack this question a little bit and perhaps hazard a few thoughts as to where you come down on it?

We were talking earlier about the paradoxes of civil war, and this is another fundamental one. What so horrified the Romans about civil war was that it was fought against intimate enemies, fellow citizens. That’s really a metonym or a synecdoche for civil war as a whole. What’s so horrifying is that recognition of familiarity with the enemy. The enemy is us. We recognize ourselves in them. We affirm commonality in the moment of collapse into enmity and destruction. That has revealing effects in terms of what the community is and what its boundaries are. Think back to what we now call the American Revolution in the 1770s. In that period contemporaries on both sides of the Atlantic talked about civil war, even an “American Civil War.” There was a recognition of the commonality of British settlers in North America, even Britons on both sides of the Atlantic. Writers at the time, including authors of fiction, figured civil war as a division among families and bloodlines—as a war within intimate communities. That is reproduced across the history of civil war. One other reason why civil wars are so difficult to conclude is that intimate enmity, that destructive familiarity, creates psychological wounds which are harder to overcome than those in wars easier to type as unfamiliar, fought against distant, hostile, inhuman enemies.

Given all of that, one of the surprises of doing research on this question was that, while I hadn’t expected to find anybody who defended civil war, interesting strains of this notion appear in the 18th century, and even as late as the Spanish Civil War. Some argued that civil war was purgative for a corrupted or divided nation, that it can be necessary to burn off the worst political and ethical tendencies within a community. There’s also the sacrifice of war itself, which some have said may be purifying and ennobling. That goes against the discussion of civil war as the most horrifying of all forms of human contention. I wouldn’t be surprised if we hear a version of that ennobling-conflict language in the coming months, especially with regard to the global scene, among thinkers in the Trump orbit.