War! What Is It Good For? A Lot

It is bloody, expensive, and decimates populations. But history professor Ian Morris also argues that war has made humanity safer and richer over the last 10,000 years.

Bob Strong/Reuters

Ronald Reagan once joked that these are the 10 most terrifying words in the English language: “Hi, I’m from the government, and I’m here to help.” Ian Morris, a professor of history and classics at Stanford, would modify Reagan’s remark. “In reality, the 10 scariest words are ‘There is no government, and I’m here to kill you.’”

Does government enhance or diminish the safety of the governed? Answers depend on your view of human nature. Rousseau maintained that humans are peaceful in their natural state; wars result from the corrupting influences of civilization. Thomas Hobbes was less optimistic. Before the restraining effects of governments, he argued, we lived in “continual fear and danger of violent death.” The intellectual descendants of Hobbes and Rousseau tend to regard government as either a cure for or a cause of violence.

Morris thinks this question is an empirical one, and his new book proposes an answer that he finds astonishing. In War! What Is It Good For? Conflict and the Progress of Civilization from Primates to Robots, Morris advances the claim that war has made humanity safer and richer over the last 10,000 years. Governments played an essential role in this process: “War made governments, and governments made peace.”

This was not quite how things appeared to the Caledonian chieftain Calgacus before he fought the invading Roman army in AD 83. “They call stealing, killing, and rape by the lying name government! They make a wasteland and call it peace!” He was articulating an objection to Morris’ thesis with dozens of parallels from different periods: From the standpoint of the conquered, war hardly seems to promote peace.

But the Roman orator Cicero felt that Calgacus and the peoples vanquished by Rome were missing a broader point. Without the protection and authority of a strong ruling government, provinces would endure endless local and civil wars and remain vulnerable to raiders and invasions. Taxes were a small price to pay for the peace and prosperity Rome provided.

Cicero’s claim was conveniently aligned with the interests of the Roman elite, and it prefigures the self-justifications of many later conquerors. When Rudyard Kipling evoked “the savage wars of peace” in his infamous poem The White Man’s Burden, he described the same paradox of violent conquest that, however circuitously, led to long-term reductions in violence.

Kipling’s belief in the racial inferiority of non-Europeans motivated his faith in colonialism. After Kipling, European men analyzing how incorporation into a larger political unit affects rates of violence risk being seriously misunderstood. To be perfectly clear, Morris is not writing a defense of Kipling, and assumptions about the “characters” of races have no role in his inquiry. But his conclusion is that Cicero and Kipling got something right. Over the long sweep of human history, savage wars did bring peace.

A long temporal lens is essential to understanding Morris’ argument. On small timescales, counterexamples of wars driving spikes in violence abound. The period of battle between Calgacus’ men and the Roman army was incredibly violent. When they were particularly piqued, Roman soldiers destroyed opponents so thoroughly that entire towns disappeared for decades. Even enemy dogs were sliced in two.

After assimilation into the Roman Empire, however, the rival warlords of countless feuding tribes became subject to Roman taxes and laws. Tribes killing their neighbors and burning their fields were now depriving the Romans of soldiers to conscript and produce to tax. The Romans didn’t decrease violence because of benevolent motives; they did so out of self-interest. Nonviolent subjects were easier to rule and more likely to provide the revenue and manpower that would enable further conquest. A self-feeding loop arose: conquest by larger political units prevented smaller groups from fighting, and this peace enabled prosperity that funded further conquest.

Sometimes the smaller groups would band together in defense against invading forces like the Romans, but the ultimate effect was the same. They would either be annexed to a larger unit after defeat, or they would form one preemptively to avoid defeat.

This logic is sound only if small political units and tribes really did suffer from high rates of violent death. Hobbes lacked the data of archaeology and anthropology to inform his theories about the dangerous nature of pre-state existence. Morris, however, marshals a wide array of evidence from both disciplines to calculate a violent death rate of 10 to 15 percent in Stone Age societies.

The invention of farming was the initial cause of wars that created peace. Agriculture supported larger populations and gave them more goods to fight over. While nomadic hunter-gatherers could simply migrate if they lost a violent conflict, agrarians were more invested in the crops and dwellings of a single location. The sociologist Michael Mann called this process by which wars create larger and more productive societies “caging.” Winners absorbed losers into larger political units more capable of absorbing still other small groups or inspiring the formation of rival states for defense.

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As wars turned productive, a series of new technologies and strategies conferred temporary advantages that were soon challenged by other advances. The first unambiguous evidence of fortification walls dates from around 4300 BC in what is now Turkey. But it wasn’t long before fortified settlements began to succumb to newly developed siege tactics. A similar pattern occurred when metal swords, armor, cavalry charges and dense infantry ranks developed. Each advance inspired tools and techniques that neutralized it.

The rise of professional armies using sophisticated war technologies gradually decreased the number of small-scale societies that could fight one another. Regional powers and empires soon swallowed many of the squabbling local tribes and enforced some level of peace, even if only as a means to further war.

Morris elucidates this pattern with an abundance of case studies. He’s sensitive to exceptions and regional particularities, and he’s candid about the paucity of data from certain areas and periods. But he shows that despite variations, the same process played out in ancient China, ancient Rome, ancient India, and the ancient Mesoamerican world. The rise of large and organized states seems to be a universal response to caging.

An equally universal phenomenon is imperial overreaching by large states. The 19th-century military strategist Carl von Clausewitz coined the term “culminating point” to describe the moment at which the costs of continued military expansion outweigh the benefits. When a culminating point is passed, productive wars turn counterproductive and begin to splinter empires into smaller political units that are typically more impoverished and violent than their predecessors.

The problem, as many an emperor could confirm, is that culminating points are easiest to identify in retrospect. As the costs of conquering additional territories increase and the returns diminish, governments often struggle to raise the revenue to pay troops. If troops abandon the empire’s borders, raiders seize the chance to strike unprotected areas. Violence spikes, and traders stay home and fail to make money the government could tax to pay the troops. The self-feeding loop switches from expansion to contraction, and this eventually creates the fractured and violent conditions necessary for a new series of productive wars.

Morris sees the 500 years of European colonial expansion from 1415 to 1914 as the most productive sequence of wars in the history of humanity. The technologies of war became more deadly and the planet grew more populous, so the death tolls were often enormous. But the percentage of humans who died a violent death continued to drop from the Stone Age rate of 10 to 15 percent. Huge new global markets emerged, and people became both richer and safer.

One problem with such analysis is that it only applies over long timescales. Human lives occur within smaller horizons. For the enslaved and colonized, the fact that their descendants may eventually live in more peaceful and prosperous societies than the violent and poor world of their ancestors is a weak consolation.

Whether eventual gains in safety and prosperity can excuse cruelty and violence in the short term is a difficult question, and it’s complicated by the unquantifiable cultural losses that result from the absorption of dozens of distinct societies into broader political structures. These are questions without easy answers, and Morris largely avoids them. The novels of authors like Chinua Achebe and Chris Abani might ultimately be better means of exploring them than a data-driven work of historical analysis.

Morris’ argument incorporates everything from the evolutionary payoffs of warfare in chimpanzee societies to a geopolitical analysis of the contemporary political landscape, where nuclear and cyber warfare are looming threats. His mastery of multiple fields is not only impressive, it’s what enables him to perceive fundamental patterns in human history. Just as he did in Why the West Rules—For Now, Morris breaks beyond the blinkered specialization so common in academia and advances an important thesis in an engaging and lucid style. There isn’t always a trade-off between depth and breadth; some authors achieve both.

Morris sees America’s current position as frighteningly reminiscent of Britain’s before the First World War. Like Britain in the early 20th century, America in the early 21st is an empire in moderate decline, a paradoxical victim of the success of its efforts to create open markets around the globe. The prospect that China, India, Russia, and America might replay the power struggles of World War I with potent biological and nuclear weapons is terrifying.

Optimists see robotic and cyber warfare largely supplanting human conflict. If another global war does occur, they argue, symbolic skirmishes between machines would involve humans only as spectators and remote strategists. Many darker possibilities, however, are also being modeled and considered by military strategists and analysts.

The average person is now 20 times less likely to die a violent death than a human in the Stone Age. We seem to be gradually evolving into less violent creatures, but the deep history of conflict in our past should temper excessive optimism. The earliest clear evidence of a human killed by a spear dates to roughly 100,000 years ago. What stories the skeletal remains of our century will tell remains to be seen.