THE departure of the last American troops from Iraq brings relief to a nation that has endured its most painful war since Vietnam. But the event is momentous for another reason. The invasion of Iraq was the most recent example of an all-out war between two national armies. And it could very well be the last one.
The idea that war is obsolescent may seem preposterously utopian. Aren’t we facing an endless war on terror, a clash of civilizations, the menace of nuclear rogue states? Isn’t war in our genes, something that will always be with us?
The theory that war is becoming passé gained traction in the late 1980s, when scholars noticed some curious nonevents. World War III, a nuclear Armageddon, was once considered inevitable, but didn’t happen. Nor had any wars between great powers occurred since the Korean War. European nations, which for centuries had fought each other at the drop of a hat, had not done so for four decades.
How has the world fared since then? Armed conflict hasn’t vanished, and today anyone with a mobile phone can broadcast the bloodshed. But our impressions of the prevalence of war, stoked by these images, can be misleading. Only objective numbers can identify the trends.
“War” is a fuzzy category, shading from global conflagrations to neighborhood turf battles, so the organizations that track the frequency and damage of war over time need a precise yardstick. A common definition picks out armed conflicts that cause at least 1,000 battle deaths in a year — soldiers and civilians killed by war violence, excluding the difficult-to-quantify indirect deaths resulting from hunger and disease. “Interstate wars” are those fought between national armies and have historically been the deadliest.
These prototypical wars have become increasingly rare, and the world hasn’t seen one since the three-week invasion of Iraq in 2003. The lopsided five-day clash between Russia and Georgia in 2008 misses the threshold, as do sporadic clashes between North and South Korea or Thailand and Cambodia.
Countries remain armed and hostile, so war is hardly impossible. But where would a new interstate war plausibly erupt? Robert Gates, the former secretary of defense, said this year that “any future defense secretary who advises the president to again send a big American land army into Asia or into the Middle East or Africa should have his head examined.”
Chinese leaders would deserve a similar workup if they blew off the very basis of their legitimacy, namely trade-based prosperity, by starting a war. (China has not fought a battle in 23 years.) India and Pakistan came dangerously close to war in 2002, but they backed off when both sides realized that millions would die and have since stabilized relations. Neither North nor South Korea could win a war at an acceptable cost.
What about other kinds of armed conflict, like civil wars and conflicts that miss the 1,000-death cutoff? Remarkably, they too have been in decline. Civil wars are fewer, smaller and more localized. Terrible flare-ups occur, and for those caught in the middle the results are devastating — but far fewer people are caught in the middle. The biggest continuing war, in Afghanistan, last year killed about 500 Americans, 100 other coalition troops and 5,000 Afghans including civilians. That toll, while deplorable, is a fraction of those in past wars like Vietnam, which killed 5,000 Americans and nearly 150,000 Vietnamese per year. Over all, the annual rate of battle deaths worldwide has fallen from almost 300 per 100,000 of world population during World War II, to almost 30 during Korea, to the low teens during Vietnam, to single digits in the late 1970s and 1980s, to fewer than 1 in the 21st century.
As the political scientist John Mueller has pointed out, today’s civil wars are closer to organized crime than traditional war. Armed militias — really gangs of thugs — monopolize resources like cocaine in Colombia or coltan in Congo, or terrorize the locals into paying tribute to religious fanatics, as in Somalia, Nigeria and the Philippines.
Nor has the suffering merely been displaced from soldiers to civilians. The much-quoted statistic that war deaths a century ago were 90 percent military and 10 percent civilian, while today the ratio is reversed, resulted from an error in a 1994 United Nations report that mistakenly compared deaths in World War I with refugees and wounded in the 1980s. The real ratio is around 50-50 and stable through time. Yes, atrocities against civilians continue, but consider a historical perspective. During World War II, Allied forces repeatedly and deliberately firebombed Axis cities, incinerating tens of thousands of civilians in a night. The Germans and Japanese did far worse. Today’s rapes, ethnic cleansings and suicide bombings are just as atrocious, but much smaller in scale.
Why is war in decline? For one thing, it no longer pays. For centuries, wars reallocated huge territories, as empires were agglomerated or dismantled and states wiped off the map. But since shortly after World War II, virtually no borders have changed by force, and no member of the United Nations has disappeared through conquest. The Korean War caused a million battle deaths, but the border ended up where it started. The Iran-Iraq War killed 650,000 with the same result. Iraq’s annexation of Kuwait in 1990 backfired. Israel seized land in 1967, but since then most has been returned and the rest remains contested.
The futility of conquest is part of the emergence of an international community regulated by norms and taboos and wielding more effective tools for managing conflicts. Among those tools, the United Nations’ 100,000 deployed peacekeepers have measurably improved the success of peace agreements in civil wars.
War also declines as prosperity and trade rise. Historically, wealth came from land and conquest was profitable. Today, wealth comes from trade, and war only hurts. When leaders’ power depends on delivering economic growth, and when a country’s government becomes richer and stronger than its warlords, war loses its appeal.
Perhaps the deepest cause of the waning of war is a growing repugnance toward institutionalized violence. Brutal customs that were commonplace for millennia have been largely abolished: cannibalism, human sacrifice, heretic-burning, chattel slavery, punitive mutilation, sadistic executions. Could war really be going the way of slave auctions? Nothing in our nature rules it out. True, we still harbor demons like greed, dominance, revenge and self-deception. But we also have faculties that inhibit them, like self-control, empathy, reason and a sense of fairness. We will always have the capacity to kill one another in large numbers, but with effort we can safeguard the norms and institutions that have made war increasingly repugnant.
Joshua S. Goldstein, professor emeritus of international relations at American University, is the author of “Winning the War on War: The Decline of Armed Conflict Worldwide.” Steven Pinker, a psychology professor at Harvard, is the author of “The Better Angels of Our Nature: Why Violence Has Declined.”
A version of this op-ed appeared in print on December 18, 2011, on page SR4 of the New York edition with the headline: War Really Is Going Out of Style.