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World War II was 75 years ago. But big wars can still happen.

The idea that war is a thing of the past creates complacency

- September 1, 2020

Sept. 2, 2020, marks the 75th anniversary of the formal end of World War II. There hasn’t been a “hot” war between great powers since. And since the 2011 publication of cognitive psychologist Steven Pinker’s book, “The Better Angels of Our Nature,” optimism about trends in warfare, once in short supply, have gone mainstream.

But social science research since the publication of Pinker’s book paints a much more nuanced and less optimistic picture. Here are some further thoughts about the prospect of war.

War is less frequent than it used to be

First, the good news: The use of force by one country against another has become significantly less common since about 1990. As I show in my recent book, “Only the Dead: The Persistence of War in the Modern Age,” once we factor in the dramatic growth in the number of countries in the world (from 64 in 1945 to 195 today) and discount those, like Iceland and Argentina, that are prohibitively far apart, we can see that countries choose to use force against one another less than half as often as they did during the Cold War.

But it’s difficult to attribute this outcome to an ongoing change in attitudes toward war, for a few reasons. The general trend before the end of the Cold War was toward more interstate conflict, not less. And the fact that an abrupt decline happened at the end of the Cold War strongly suggests that the end of global competition between the United States and the Soviet Union deserves credit — especially given the sharp decline in insurgencies that happened at the same time.

The absence of a major war since 1945 is not as remarkable as you might think

What about the absence of really big, really lethal wars in the past 75 years, especially among developed countries and democracies? It’s certainly real, and of course it’s good news in and of itself.

But really big wars are rare to begin with. Sometimes they happen relatively close together (as in the two world wars); other times, they can be very far apart. Nearly a century separated the end of the Napoleonic Wars and the start of World War I, for example. That’s why it’s unwise to read too much into a long period of calm. It’s possible that the world has changed, but it’s also possible that such a long period isn’t very remarkable from a statistical perspective.

To get at the question of whether big wars have really become less likely, we can take advantage of a curious property of large wars: As scholars have long known, a war that is twice as deadly as another war is about three times as rare. If wars have become less lethal since 1945, we should see a change in that two-to-three ratio.

Scholars who have looked for differences in that ratio across the past two centuries almost uniformly come to the same conclusion: Nothing has changed. Even though chance has not yet produced another war at the top end of the scale, the odds that it will do so have not decreased. These conclusions have prompted some statistical rejoinders, but even these don’t claim that the risk of a huge, deadly war has disappeared entirely. The best-case scenario is that it has declined slightly — certainly not enough of a decline to be of much comfort.

It’s worth pausing to dwell on how remarkable this conclusion is. Nuclear weapons, which deter conflict not just for nuclear states but for their allies as well, have not decreased the lethality of war once it breaks out. Nor has battlefield medicine, which, as political scientist Tanisha Fazal’s research has shown, has dramatically improved on battlefield survival rates. Indeed, advances in this area may be the only reason we haven’t seen an increase in the lethality of war.

The perception that war is ‘over’ is a Western-centric view

Why, then, is there a widespread perception that humanity is on the verge of vanquishing the scourge of war? One uncomfortably common thread among optimists is the emphasis on trends in the Western world, which makes up less than 20 percent of the world’s population, while downplaying developments elsewhere.

For example, the “Long Peace,” a term historian John Lewis Gaddis originally applied to the absence of large-scale war among great powers, was distinctly not peaceful in the developing world. As former International Studies Association president Amitav Acharya points out, discussions of postwar “stability” generally ignore the fact that “regional conflicts raged throughout the Third World despite, or perhaps because of, the interventionism of the superpowers.”

The perception that really deadly wars are a thing of the past, too, owes quite a bit to a narrow focus on the West. If we measure war’s lethality in per capita terms, three wars since 1815 have been even deadlier than the two world wars: the Iran-Iraq war of the 1980s, the Chaco War in the 1930s, and the spectacularly lethal Paraguayan War in the 1860s, which resulted in the deaths of at least 25 percent, and possibly as much as 60 to 70 percent, of the country’s total population.

Even today, amid reassurances from optimists like Pinker, India and China — two nuclear-armed, non-Western countries whose combined population exceeds that of the world in 1940 — have been engaging in lethal brinkmanship along their border. And as the Cold War demonstrated, nuclear weapons create a disturbingly high risk of accidental nuclear war.

Regardless of how we came to believe it, though, the idea that war is a thing of the past creates the very real danger of complacency, which could lead politicians and the public to underestimate war’s dangers. Indeed, the ongoing erosion of international institutions and the apparent willingness of Americans to countenance nuclear first use are consistent with just such an outcome.

World War II killed about 3 percent of the world’s population. The intervening years have been relatively peaceful — for some. But the inhabitants of that island of peace risk learning the wrong lessons from that peace, even as their island’s shoreline gradually erodes.

Bear F. Braumoeller (@Prof_BearB) holds the Baronov and Timashev Chair in Data Analytics and is a professor in the Department of Political Science at Ohio State University. The author of “Only the Dead: The Persistence of War in the Modern Age” (Oxford University Press, 2019), his research focuses on international conflict, international order and computational social science.

Note: Updated Oct. 5, 2023.