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Imagine I have a deck of 96 cards. The most common card has 1,000 battle deaths, but one of the cards is World War I, and one of the cards is World War II. How worried should you be about drawing a card from that deck?

You could say, “Well, most of them are 1,000 battle deaths, so I shouldn’t be too worried.” But at the same time, World War I and World War II are in there, and if the deck hasn’t changed, we really need to be thoughtful about when it is we’re going to draw another card.

Bear Braumoeller

Is war in long-term decline? Steven Pinker’s The Better Angels of Our Nature brought this previously obscure academic question to the centre of public debate, and pointed to rates of death in war to argue energetically that war is on the way out.

But that idea divides war scholars and statisticians, and so Better Angels has prompted a spirited debate, with datasets and statistical analyses exchanged back and forth year after year. The lack of consensus has left a somewhat bewildered public (including host Rob Wiblin) unsure quite what to believe.

Today’s guest, professor in political science Bear Braumoeller, is one of the scholars who believes we lack convincing evidence that warlikeness is in long-term decline. He collected the analysis that led him to that conclusion in his 2019 book, Only the Dead: The Persistence of War in the Modern Age.

The question is of great practical importance. The US and PRC are entering a period of renewed great power competition, with Taiwan as a potential trigger for war, and Russia is once more invading and attempting to annex the territory of its neighbours.

If war has been going out of fashion since the start of the Enlightenment, we might console ourselves that however nerve-wracking these present circumstances may feel, modern culture will throw up powerful barriers to another world war. But if we’re as war-prone as we ever have been, one need only inspect the record of the 20th century to recoil in horror at what might await us in the 21st.

Bear argues that the second reaction is the appropriate one. The world has gone up in flames many times through history, with roughly 0.5% of the population dying in the Napoleonic Wars, 1% in World War I, 3% in World War II, and perhaps 10% during the Mongol conquests. And with no reason to think similar catastrophes are any less likely today, complacency could lead us to sleepwalk into disaster.

He gets to this conclusion primarily by analysing the datasets of the decades-old Correlates of War project, which aspires to track all interstate conflicts and battlefield deaths since 1815. In Only the Dead, he chops up and inspects this data dozens of different ways, to test if there are any shifts over time which seem larger than what could be explained by chance variation alone.

Among other metrics, Bear looks at:

  • Battlefield deaths alone, as a percentage of combatants’ populations, and as a percentage of world population.
  • The total number of wars starting in a given year.
  • Rates of war initiation as a fraction of all country pairs capable of fighting wars.
  • How likely it was during different periods that a given war would double in size.
Image source.

In a nutshell, and taking in the full picture painted by these different measures, Bear simply finds no general trend in either direction from 1815 through today. It seems like, as philosopher George Santayana lamented in 1922, “only the dead have seen the end of war”.

That’s not to say things are the same in all periods. Depending on which indication of warlikeness you give the greatest weight, you can point to some periods that seem violent or pacific beyond what might be explained by random variation.

For instance, Bear points out that war initiation really did go down a lot at the end of the Cold War, with peace probably fostered by a period of unipolar US dominance, and the end of great power funding for proxy wars.

But that drop came after a period of somewhat above-average warlikeness during the Cold War. And surprisingly, the most peaceful period in Europe turns out not to be 1990–2015, but rather 1815–1855, during which the monarchical ‘Concert of Europe,’ scarred by the Napoleonic Wars, worked together to prevent revolution and interstate aggression.

Why haven’t modern ideas about the immorality of violence led to the decline of war, when it’s such a natural thing to expect? Bear is no Enlightenment scholar, but his book notes (among other reasons) that while modernity threw up new reasons to embrace pacifism, it also gave us new reasons to embrace violence: as a means to overthrow monarchy, distribute the means of production more equally, or protect people a continent away from ethnic cleansing — all motives that would have been foreign in the 15th century.

In today’s conversation, Bear and Rob discuss all of the above in more detail than even a usual 80,000 Hours podcast episode, as well as:

  • What would Bear’s critics say in response to all this?
  • What do the optimists get right?
  • What are the biggest problems with the Correlates of War dataset?
  • How does one do proper statistical tests for events that are clumped together, like war deaths?
  • Why are deaths in war so concentrated in a handful of the most extreme events?
  • Did the ideas of the Enlightenment promote nonviolence, on balance?
  • Were early states more or less violent than groups of hunter-gatherers?
  • If Bear is right, what can be done?
  • How did the ‘Concert of Europe’ or ‘Bismarckian system’ maintain peace in the 19th century?
  • Which wars are remarkable but largely unknown?
  • What’s the connection between individual attitudes and group behaviour?
  • Is it a problem that this dataset looks at just the ‘state system’ and ‘battlefield deaths’?

Get this episode by subscribing to our podcast on the world’s most pressing problems and how to solve them: type ‘80,000 Hours’ into your podcasting app. Or read the transcript below.

Producer: Keiran Harris
Audio mastering: Ryan Kessler
Transcriptions: Katy Moore


*Only the Dead* bottom lines

Bear Braumoeller: I wish there was just one bottom line, but there are a few. The first one is that there are a lot of reasons to be sceptical about the data and arguments that have been presented in favour of the decline of war argument. And this was a big part of my frustration in reading Better Angels in particular. I was looking forward to these nuggets of data, and the statistical tests, and so on and so forth, and I just didn’t see that.

Some other scholars have accused Pinker of cherry-picking the data. I didn’t do that in the book, but I’ve read that criticism, and I don’t think it’s completely unfair. Just for one example, he provided a graph of war in decline from a conference paper that never got published, and I dug up the conference paper and it was one of six graphs, and it was the only one that showed war in decline.

Bear Braumoeller: That’s one issue. Another is that the analysis of the data is really lacking. And this is a point that Nassim Taleb has made often and at length in particular: that there are no actual tests of the argument, in the sense of a formal statistical test that would help you distinguish signal from noise. That’s what statistical tests do. So it looks a lot more impressive, I think, to people who don’t do data analytics than it actually is to the people who do. That’s one bottom line.

Bear Braumoeller: The second bottom line is that when you do test the argument that war is in decline, it’s really hard to find support for it. And I was clear about this in the book: I wanted Pinker to be right. My hope was that I was going to find trends that were going to support the argument. But I looked at three different meanings of the phrase “decline of war,” and I only found a decline in one of them, and that was only at the end of the Cold War. Mostly, there’s just been no change over the past couple hundred years. And you could even argue that there’d been some evidence of increase in warfare prior to the end of the Cold War. So that’s number two.

Rob Wiblin: I guess the key scary finding is just that there’s not really any evidence that would make us feel confident that the threat that we face from war today is materially less than the threat that people have faced at many other times through history — times in which enormous, horrific wars broke out, and war was one of the most regularly destructive forces out there.

Bear Braumoeller: Correct.

Rob Wiblin: So we just shouldn’t be sanguine about the issue, I suppose is the bottom line. And what’s another key conclusion?

Bear Braumoeller: I think the third bottom line is that there is some hope. I don’t mean it to be an entirely negative conclusion. As you mentioned, patterns of international order I think are much better predictors of variation in international conflict than human progress over time. You don’t see a tonne of variation in conflict across the entire system over time. You do see variation across groups of states, and specifically across and within international orders — like the liberal international order, the Soviet communist order, the Concert of Europe, and so on.

So I think that in some ways I kind of do agree with people who argue that we’ve made progress. I think we’ve created something really impressive. Michael Howard wrote a book about international order where he referred to it as “the invention of peace.” So I think there is some hope if we can get a better handle on international order. The thing is we don’t really know how to use it. We don’t have a very good sense of how to optimise configurations of international order to create as much peace as possible.

The Enlightenment

Rob Wiblin: I’m really interested in this issue, because I think I probably had a strong preconception that the Enlightenment — and all of the intellectual advances that stemmed from that over the last 250 years — that that probably was pushing us towards a more reasonable world, in which conflict was less likely. That certainly would have been my assumption, coming in. I’ve changed my mind on that over the last few years, or at least I view it now as a lot less clear. And I feel like I had all the knowledge necessary to realise that that was a much less clear claim than what I thought it was.

So there are ways in which intellectual changes in the 17th and 18th centuries might push us towards peace, but there are also ways in which they might not — and in fact, did not. Can you lay out some of those?

Bear Braumoeller: Sure. The word “enlightenment” just has such positive connotations. You tend to attribute all good things that came after the Enlightenment to some degree of enlightenment. But you’re exactly right that the Enlightenment gave rise to a lot of ideas, and some of those ideas made war more acceptable for new reasons that hadn’t existed before. Herder and nationalism, for example. Hegel and Marx on the value of a strong state. Justifications for uprising against monarchies, the invention of wars for peace in the Greek Civil War. Interventions in order to stop war. All of these are grounded, very firmly, in Enlightenment ideas. Everyone loves to talk about Emmanuel Kant, but Kant wasn’t the whole Enlightenment. So that’s one general point.

The other one is Enlightenment ideas, even when they have been sort of progressive and positive, have given rise to very illiberal reactions on the part of people who were dissatisfied with modernity. The recent waves of populist movements, for example, is a good illustration of that. These are fundamentally nationalistic, illiberal movements. So there are a couple of ways in which you can’t really draw a straight arrow from the Enlightenment to peace.

Rob Wiblin: Right. So yeah, this is a big, big shift in my thinking here. I was thinking about it: What is the Enlightenment? What is it fair to say is a consequence of the Enlightenment? Is it kind of unclear? It’s obviously a vague concept. It’s a difficult, undefined question.

Bear Braumoeller: Now, again, the caveat is I’m not an Enlightenment specialist, so take it with a grain of salt. But you know, you see much more of a fundamental reliance on reason as a vector to truth than revelation or faith. And it’s a fundamental reorientation of society. It had a tremendous, just incredibly pervasive impact, the more it spread. There were actually a variety of different enlightenments in different places at different times, but the overall trend was more toward a focus on better ways to truth. And you see that in the rise of universities, the rise of science, all sorts of different ways. But reason can lead you to some pretty dark places too.

Rob Wiblin: Yes. And even if it’s leading you in a good direction in the long term, it could be an extremely bloody path to get there, arguably.

Bear Braumoeller: Yes.

International orders

Rob Wiblin: You talk about how there’s these different eras of international order. I suppose you could say, after the Cold War, there was a new one. And arguably, I suppose we’re entering into a new international order, with China being more assertive, and refusing to be constrained by the order that predominated in the year 2000, for example. Are there different “classes”? If you had to list “Here are the four different kinds of international order,” what would they be? Or is that the wrong way to think about it?

Bear Braumoeller: No, it’s fine. I mean, very broadly, I think the categorisation that makes most sense to me is: there are orders that are negotiated — the liberal international order would be a good example of a negotiated order among countries. There are orders that are imposed — like empires, where the subsidiary states don’t really have a choice, or the choices that they’re given are so unpalatable that they effectively don’t have a choice. And then there’s a third category that libertarians are particularly fond of: the spontaneous order — where interactions just spontaneously give rise to mutual expectations and rules of the road. So in a very broad sense, I think you can break orders down into those types.

Rob Wiblin: And is it fair to say that basically, the story with international orders is that once a bloc of countries has established an international order, internally, they tend to have substantially lower rates of violent conflict. However, if you have more than one international order on the scene at any one point in time, then their tendency to fight with one another is pretty substantial. And so, whether they’re good or bad, it’s kind of a balancing between these two things: that internally, they’re relatively peaceful, and externally, they can be quite aggressive.

Bear Braumoeller: Right. Yeah, exactly.

Rob Wiblin: That doesn’t comment on the anarchy situation, or the situation where there is no order. How does that perform?

Bear Braumoeller: Well, anarchy is, in a way, kind of the baseline condition. And it tends to be certainly more conflictual than life under international orders, and generally more conflictual than relationships across orders as well.

Rob Wiblin: Really? OK, so it’s really kind of the worst case.

Bear Braumoeller: It’s a really interesting question. So I wrote this book, and what I observed was higher rates of conflict initiation across international orders. I just sort of assumed what happens is you get two different groups forming, and once you have an in-group effect, you get a cross-group conflict. Well, it turns out that there’s a whole psych literature on this, and that doesn’t generally happen. In-group effect doesn’t automatically lead to out-group conflict.

So my lab and I came up with a model of how it is that hierarchy, and hierarchical order, and international war are related to each other. And we also found, in that model, that just the formation of multiple hierarchies, in and of itself, doesn’t cause an increase in conflict between them. So, it’s a really interesting puzzle of why it is you see increased rates of conflict initiation. And I’ve got a couple of answers that are potentially worth considering.

One is that multiple international orders don’t cause increased levels of conflict; increased levels of conflict cause multiple international orders. So the world becomes more dangerous, and as a response to that danger, you see international orders form. Which actually maps very well to the trajectory of the Western liberal order and the Soviet communist order after World War II. They fought on the same side, and only gradually did each realise that the other was a threat. And as that perception of threat increased more and more, there was an increasing tendency to try to form orders, to kind of counteract it. So that may be one reason that you see more conflict across multiple orders: that conflict creates orders.

Rob Wiblin: It’s reverse causation.

Bear Braumoeller: Yeah, exactly.

Why Bear thinks he and Steven Pinker disagree

Bear Braumoeller: My sense of why Pinker and I are coming from different places — and this may relate to broader groups of people and society in a nutshell — is that he’s a psychologist and I’m a political scientist. He locates the drivers of behaviour inside individual humans. And I think a lot of people reflexively do that.

I study the world. And political scientists, and sociologists, and other social scientists in these areas study the way that individual incentives produce group behaviour. And fundamental to that perspective is something called the ecological inference fallacy — that is, the idea that you can infer group behaviour from individual characteristics or vice versa.

Which clearly isn’t the case. One example: in the US, wealthier states vote democratic. But you can’t, from that, infer that wealthier people vote democratic. In fact, wealthier people vote Republican. So the characteristics of individuals don’t necessarily have anything to do with the characteristics of aggregates, because aggregates don’t just transmit people’s preferences directly.

So while he does acknowledge the role of the state at the start of his story, most of his story is about what’s happening inside human minds over time. And I think that’s a story that is easy for people to wrap their heads around, and intuitively connects to the way that people think about the world. But one of my biggest problems when I was reading through the book is that human aggregates have their own dynamics and characteristics. And where those come from is actually a fascinating set of topics, but you can’t just take it for granted.

Rob Wiblin: Yeah, that’s fascinating. So people whose fields naturally study individuals might notice that on an individual level, people’s attitudes towards violence are changing radically. Perhaps someone in 1800 would have been far more likely to endorse violence as a legitimate response to something than someone in a survey today. And then it’s very natural to go from that and say, “Well, doesn’t that strongly suggest that war must be on the decline?”

And you’re saying, not necessarily — because war is mediated by many things, not just individual dispositions. It’s about behaviour in groups. Maybe the incentives for states have changed and the technology has changed, and all these other things have changed that could cause war to be even more common and more destructive, despite people disliking it even more than they did, oddly enough.

Bear Braumoeller: Well, it’s not even necessarily that those factors would be outweighed by other factors. My colleague at Ohio State, John Mueller, is another one of the folks who argues in favour of decline of war. And I think he makes a really good point, which is that antiwar sentiment — the idea that we have to abolish war — really reached its peak between World War I and World War II. I mean, the 1930s was the heyday of the “Let’s make war illegal” movement — the Kellogg–Briand Pact and so on and so forth.

Bear Braumoeller: It didn’t work. That’s the thing. And John’s reaction to that point is, “Well, that has to do with Adolf Hitler. It was just one guy didn’t get the memo.” Well, arguably…

Rob Wiblin: But it seems like a peace that fragile…

Bear Braumoeller: Yes. If one guy not getting the memo can cause World War II, that’s a big problem. Then we shouldn’t be studying what people in general believe at all. But also, you could make a good argument that the antiwar sentiment in the 1930s made Hitler’s rise easier: that people were complacent; they thought that they’d managed to find a lasting peace. And as a result, were less willing to stand up to it.

Rates of violent death throughout history

Rob Wiblin: This is a slightly separate issue, but while we’re on these methodological questions, a lot of people believe that rates of violent death before the rise of modern states and empires — like the Persian Empire, the Roman Empire, and so on — that rates of violent death, including homicide, was far higher than it is today. So now we’re kind of talking about hunter-gatherers compared to the Roman Empire. How confident can we be about that claim, that over that very long time periods, rates of interpersonal violence have declined?

Bear Braumoeller: So this one is a bit outside my area, but just based on looking at the evidence, it strikes me as being really debatable. The archeologists who have responded to this question have argued about things like “How do you know when someone’s killed in battle versus just buried with a spear next to them?” — that kind of thing. And you get heated debates over that question.

From my perspective, the key thing is that small groups naturally produce higher variation in outcomes than large groups. A good example from recent years is you look at maps of COVID prevalence by county. Probably everyone here has seen one of these maps, where you see there’s a lot in New York City, there’s less in Philadelphia, that sort of thing. But when you look at the western part of the US, all of a sudden you get this incredible array of checker-boarded rates: some are really high, some are really low. And that’s because some of those counties have 10 people in them. And if 10 people get COVID in that county, then…

Rob Wiblin: 100%.

Bear Braumoeller: So what you see in those counties is more variation. At least in my data visualisation class, my students are always trying to read something meaningful into that pattern in the map data, and say, “Oh, what is it about this county?” I’m like, “It’s small, that’s what it is.” That’s what’s going on.

Rob Wiblin: Let’s just pause and emphasise this, because this is an incredibly important thing for people in the audience to have in mind when people make a very wide range of claims.

A really interesting case where this shows up is if you look at rankings of schools in terms of test performance or learning or any measure of quality. You’ll very often find that the ones at the top are very small schools. Now a very natural interpretation is that small schools are better. Maybe education is better provided at a boutique scale rather than an industrial scale. However, you absolutely have to check that the worst-performing schools are not also small. Because of course when you have a tiny cohort, it’s possible for them to knock it out of the park one year and then be absolutely garbage the next.

Small schools and small anything are going to have far more higher variance, far more dispersed outcomes. And you need to look at the full range, rather than selecting on the dependent variable — or, in this case, selecting based on high test results or low test results — because that is going to absolutely wreck your conclusion. And the application here is that, of course, pre-state societies — hunter-gatherer groups — were far smaller. So it would be possible for them to have 10% of their population die in a conflict in a given year, in a way that’s extremely difficult to happen in the United States, given its size today.

But doesn’t that also mean that some of the most peaceful-seeming societies, on average, it should cancel out? And both the most violent and the most peaceful ones will all be hunter-gatherer groups, basically?

Bear Braumoeller: Yes. And this is actually where Pinker gets accused of cherry-picking the data, because archeologists have come up with a whole bunch of, “Why didn’t you talk about the Hopi?” for example. “Why didn’t you talk about these other groups that had incredibly low rates of death by warfare?” Again, this is not my area, but that’s part of the criticism.

How worried we should be

Rob Wiblin: How can we aggregate all of the above trends to give a sense of how grave the risk of war is overall? How worried should we be?

Bear Braumoeller: So it’s sort of a mixed answer. Like I said, interstate war initiation has gotten far less common since the end of the Cold War, which is great news. From the perspective of making the world a better place, we need to understand that better. This is basically the whole reason that I formed a research lab. We’re doing things like coming up with measures of order and figuring out the logic of the relationship between order and war, and how the tensions between domestic political order and international order play out, and even looking at Chinese understandings of international order to see what kind of traction we can get on that.

So I think one takeaway is that we do sometimes see a big drop in the rate of conflict initiation that I absolutely believe in, and we need to understand what happened there. A second takeaway is that the lethality of war, like I said, no matter what I threw at it, just stubbornly refused to give me the answer that war is increasing or decreasing. People think that if a war starts now, it’s less likely to escalate into an incredibly bloody conflagration than it was in 1939 or 1913, and there’s no evidence to support that conclusion.

The final thing I’d say is that wars are so incredibly escalatory that we should really be worried about them. The analogy that I use is: imagine I have a deck of 96 cards. The most common card has 1,000 battle deaths, but one of the cards is World War I, and one of the cards is World War II. How worried should you be about drawing a card from that deck? You could say, “Well, most of them are 1,000 battle deaths, so I shouldn’t be too worried.” But at the same time, World War I and World War II are in there, and if the deck hasn’t changed, we really need to be thoughtful about when it is we’re going to draw another card.

Things that can be done to increase the prospects for peace

Bear Braumoeller: Let’s start with an understanding of war that comes from Clausewitz — but actually was really well articulated by a guy named Jim Fearon in 1995 — called the “bargaining theory of war.” He pointed out that, yes, war is an extension of politics — but in the sense that you have an issue, you negotiate over it, and war is what happens when you can’t reach a negotiated settlement. So we need to understand why you can’t reach a settlement.

From that perspective, what you’re seeing in these cases is that issues arise that people are willing to fight and die over, and they can’t arrive at a settlement short of war. How do you fix that? You can make them less committed to the values that they currently have. Ukraine could say, “I don’t really want that territory.” That’s not likely going to happen.

Bear Braumoeller: One theoretical way to do this would be to give Ukraine nuclear weapons. Do you want to do that? No. I don’t want to do that. I think it’s a terrible idea. It might increase the odds that the war will end, but if it doesn’t, it’ll probably increase the costs dramatically.

But actually, I think that the unbelievably broad, crippling sanctions that were implemented in Ukraine are a fantastic signal for China, and a warning for China that they can expect the same in Taiwan. I think actions like that actually can make a difference. It’s hard to make a difference in the current conflict, but it can make a difference for the future.

Rob Wiblin: By setting an example that you’re willing to pay a high price in order to punish territorial conquest or annexation.

Bear Braumoeller: Right. Exactly.

Rob Wiblin: OK. I’m not quite sure what the practical implication is. I suppose things are going on in the world all the time, and I want to have some opinion. Ideally, I want to say, “It would improve humanity’s prospects if country X does Y.” Then I’m trying to bring this international order framework to bear and then think, “What does this imply about policy for the UK or the US? In principle, what would I want Russia to do?” It seems like one bottom line with the international order framing is that the most peaceful state of the world would be one hegemon who is powerful enough to either dominate or ideologically sway everyone in the world, so now there’s peace within this one order and then there’s no one else to fight — I guess, unless aliens come along.

Bear Braumoeller: Or, less uncharitably, provide security for everybody.

Rob Wiblin: I see.

Bear Braumoeller: Because one way to think about it —

Rob Wiblin: If you fight amongst yourselves, we will punish the aggressor.

Bear Braumoeller: Yes, exactly. I think that’s a common understanding of how hierarchical international orders form: that it’s a trade of security for autonomy.

The smaller states say, “We’ll give you some policy thing that you want. We’ll vote with you at the UN. We’ll give you basing rights. We’ll pay cash, whatever — and you will provide security for us.” If there’s a hegemon that’s powerful enough to make that trade with all the countries in the world, then that would definitely be a situation in which you’d find more peace. We are pretty powerful, but we’ve decided to limit the scope of our security deals to democracies. That inherently limits the scope of the order.


Bear Braumoeller: I think the most hope lies in information — information about the dangers of escalation, information about other states’ likely costs of war. This is why I think sanctions were such a good thing, because they conveyed information to China that the likely costs of invading Taiwan are probably higher than they think. I think there’s room to work at the margin there. There’s also room to work by increasing the costs of invasion, which we do by bolstering the troops in the area and so on and so forth. I think there is some wiggle room there, but in terms of something large and transformational that’s going to produce a change like the end of the Cold War, it’s hard to imagine that without a fundamental restructuring of international order.

Articles, books, and other media discussed in the show

Bear’s work:

The decline of war thesis:

Data and measures of warlikeness:

International orders and conflict:

Bear’s and Rob’s “odd and quirky” wars:

Other 80,000 Hours Podcast episodes:

Everything else:

Related episodes

About the show

The 80,000 Hours Podcast features unusually in-depth conversations about the world's most pressing problems and how you can use your career to solve them. We invite guests pursuing a wide range of career paths — from academics and activists to entrepreneurs and policymakers — to analyse the case for and against working on different issues and which approaches are best for solving them.

The 80,000 Hours Podcast is produced and edited by Keiran Harris. Get in touch with feedback or guest suggestions by emailing [email protected].

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