In the teeth of these preconceptions, I will have to persuade you with numbers, which I will glean from datasets and depict in graphs. In each case I’ll explain where the numbers came from and do my best to interpret the ways they fall into place. The problem I have set out to understand is the reduction in violence at many scales—in the family, in the neighborhood, between tribes and other armed factions, and among major nations and states. If the history of violence at each level of granularity had an idiosyncratic trajectory, each would belong in a separate book. But to my repeated astonishment, the global trends in almost all of them, viewed from the vantage point of the present, point downward. That calls for documenting the various trends between a single pair of covers, and seeking commonalities in when, how, and why they have occurred.
Too many kinds of violence, I hope to convince you, have moved in the same direction for it all to be a coincidence, and that calls for an explanation. It is natural to recount the history of violence as a moral saga—a heroic struggle of justice against evil—but that is not my starting point. My approach is scientific in the broad sense of seeking explanations for why things happen. We may discover that a particular advance in peacefulness was brought about by moral entrepreneurs and their movements. But we may also discover that the explanation is more prosaic, like a change in technology, governance, commerce, or knowledge. Nor can we understand the decline of violence as an unstoppable force for progress that is carrying us toward an omega point of perfect peace. It is a collection of statistical trends in the behavior of groups of humans in various epochs, and as such it calls for an explanation in terms of psychology and history: how human minds deal with changing circumstances.
A large part of the book will explore the psychology of violence and nonviolence. The theory of mind that I will invoke is the synthesis of cognitive science, affective and cognitive neuroscience, social and evolutionary psychology, and other sciences of human nature that I explored in How the Mind Works, The Blank Slate, and The Stuff of Thought. According to this understanding, the mind is a complex system of cognitive and emotional faculties implemented in the brain which owe their basic design to the processes of evolution. Some of these faculties incline us toward various kinds of violence. Others—“the better angels of our nature,” in Abraham Lincoln’s words—incline us toward cooperation and peace. The way to explain the decline of violence is to identify the changes in our cultural and material milieu that have given our peaceable motives the upper hand.
Finally, I need to show how our history has engaged our psychology. Everything in human affairs is connected to everything else, and that is especially true of violence. Across time and space, the more peaceable societies also tend to be richer, healthier, better educated, better governed, more respectful of their women, and more likely to engage in trade. It’s not easy to tell which of these happy traits got the virtuous circle started and which went along for the ride, and it’s tempting to resign oneself to unsatisfying circularities, such as that violence declined because the culture got less violent. Social scientists distinguish “endogenous” variables—those that are inside the system, where they may be affected by the very phenomenon they are trying to explain—from the “exogenous” ones—those that are set in motion by forces from the outside. Exogenous forces can originate in the practical realm, such as changes in technology, demographics, and the mechanisms of commerce and governance. But they can also originate in the intellectual realm, as new ideas are conceived and disseminated and take on a life of their own. The most satisfying explanation of a historical change is one that identifies an exogenous trigger. To the best that the data allow it, I will try to identify exogenous forces that have engaged our mental faculties in different ways at different times and that thereby can be said to have caused the declines in violence.
The discussions that try to do justice to these questions add up to a big book—big enough that it won’t spoil the story if I preview its major conclusions. The Better Angels of Our Nature is a tale of six trends, five inner demons, four better angels, and five historical forces.
Six Trends (chapters 2 through 7). To give some coherence to the many developments that make up our species’ retreat from violence, I group them into six major trends.
The first, which took place on the scale of millennia, was the transition from the anarchy of the hunting, gathering, and horticultural societies in which our species spent most of its evolutionary history to the first agricultural civilizations with cities and governments, beginning around five thousand years ago. With that change came a reduction in the chronic raiding and feuding that characterized life in a state of nature and a more or less fivefold decrease in rates of violent death. I call this imposition of peace the Pacification Process.
The second transition spanned more than half a millennium and is best documented in Europe. Between the late Middle Ages and the 20th century, European countries saw a tenfold-to-fiftyfold decline in their rates of homicide. In his classic book The Civilizing Process, the sociologist Norbert Elias attributed this surprising decline to the consolidation of a patchwork of feudal territories into large kingdoms with centralized authority and an infrastructure of commerce. With a nod to Elias, I call this trend the Civilizing Process.
The third transition unfolded on the scale of centuries and took off around the time of the Age of Reason and the European Enlightenment in the 17th and 18th centuries (though it had antecedents in classical Greece and the Renaissance, and parallels elsewhere in the world). It saw the first organized movements to abolish socially sanctioned forms of violence like despotism, slavery, dueling, judicial torture, superstitious killing, sadistic punishment, and cruelty to animals, together with the first stirrings of systematic pacifism. Historians sometimes call this transition the Humanitarian Revolution.
The fourth major transition took place after the end of World War II. The two-thirds of a century since then have been witness to a historically unprecedented development: the great powers, and developed states in general, have stopped waging war on one another. Historians have called this blessed state of affairs the Long Peace.2
The fifth trend is also about armed combat but is more tenuous. Though it may be hard for news readers to believe, since the end of the Cold War in 1989, organized conflicts of all kinds—civil wars, genocides, repression by autocratic governments, and terrorist attacks—have declined throughout the world. In recognition of the tentative nature of this happy development, I will call it the New Peace.
Finally, the postwar era, symbolically inaugurated by the Universal Declaration of Human Rights in 1948, has seen a growing revulsion against aggression on smaller scales, including violence against ethnic minorities, women, children, homosexuals, and animals. These spin-offs from the concept of human rights—civil rights, women’s rights, children’s rights, gay rights, and animal rights—were asserted in a cascade of movements from the late 1950s to the present day which I will call the Rights Revolutions.
Five Inner Demons (chapter 8). Many people implicitly believe in the Hydraulic Theory of Violence: that humans harbor an inner drive toward aggression (a death instinct or thirst for blood), which builds up inside us and must periodically be discharged. Nothing could be further from a contemporary scientific understanding of the psychology of violence. Aggression is not a single motive, let alone a mounting urge. It is the output of several psychological systems that differ in their environmental triggers, their internal logic, their neurobiological basis, and their social distribution. Chapter 8 is devoted to explaining five of them. Predatory or instrumental violence is simply violence deployed as a practical means to an end. Dominance is the urge for authority, prestige, glory, and power, whether it takes the form of macho posturing among individuals or contests for supremacy among racial, ethnic, religious, or national groups. Revenge fuels the moralistic urge toward retribution, punishment, and justice. Sadism is pleasure taken in another’s suffering. And ideology is a shared belief system, us
ually involving a vision of utopia, that justifies unlimited violence in pursuit of unlimited good.
Four Better Angels (chapter 9). Humans are not innately good (just as they are not innately evil), but they come equipped with motives that can orient them away from violence and toward cooperation and altruism. Empathy (particularly in the sense of sympathetic concern) prompts us to feel the pain of others and to align their interests with our own. Self-control allows us to anticipate the consequences of acting on our impulses and to inhibit them accordingly. The moral sense sanctifies a set of norms and taboos that govern the interactions among people in a culture, sometimes in ways that decrease violence, though often (when the norms are tribal, authoritarian, or puritanical) in ways that increase it. And the faculty of reason allows us to extricate ourselves from our parochial vantage points, to reflect on the ways in which we live our lives, to deduce ways in which we could be better off, and to guide the application of the other better angels of our nature. In one section I will also examine the possibility that in recent history Homo sapiens has literally evolved to become less violent in the biologist’s technical sense of a change in our genome. But the focus of the book is on transformations that are strictly environmental: changes in historical circumstances that engage a fixed human nature in different ways.
Five Historical Forces (chapter 10). In the final chapter I try to bring the psychology and history back together by identifying exogenous forces that favor our peaceable motives and that have driven the multiple declines in violence.
The Leviathan, a state and judiciary with a monopoly on the legitimate use of force, can defuse the temptation of exploitative attack, inhibit the impulse for revenge, and circumvent the self-serving biases that make all parties believe they are on the side of the angels. Commerce is a positive-sum game in which everybody can win; as technological progress allows the exchange of goods and ideas over longer distances and among larger groups of trading partners, other people become more valuable alive than dead, and they are less likely to become targets of demonization and dehumanization. Feminization is the process in which cultures have increasingly respected the interests and values of women. Since violence is largely a male pastime, cultures that empower women tend to move away from the glorification of violence and are less likely to breed dangerous subcultures of rootless young men. The forces of cosmopolitanism such as literacy, mobility, and mass media can prompt people to take the perspective of people unlike themselves and to expand their circle of sympathy to embrace them. Finally, an intensifying application of knowledge and rationality to human affairs—the escalator of reason—can force people to recognize the futility of cycles of violence, to ramp down the privileging of their own interests over others’, and to reframe violence as a problem to be solved rather than a contest to be won.
As one becomes aware of the decline of violence, the world begins to look different. The past seems less innocent; the present less sinister. One starts to appreciate the small gifts of coexistence that would have seemed utopian to our ancestors: the interracial family playing in the park, the comedian who lands a zinger on the commander in chief, the countries that quietly back away from a crisis instead of escalating to war. The shift is not toward complacency: we enjoy the peace we find today because people in past generations were appalled by the violence in their time and worked to reduce it, and so we should work to reduce the violence that remains in our time. Indeed, it is a recognition of the decline of violence that best affirms that such efforts are worthwhile. Man’s inhumanity to man has long been a subject for moralization. With the knowledge that something has driven it down, we can also treat it as a matter of cause and effect. Instead of asking, “Why is there war?” we might ask, “Why is there peace?” We can obsess not just over what we have been doing wrong but also over what we have been doing right. Because we have been doing something right, and it would be good to know what, exactly, it is.
Many people have asked me how I became involved in the analysis of violence. It should not be a mystery: violence is a natural concern for anyone who studies human nature. I first learned of the decline of violence from Martin Daly and Margo Wilson’s classic book in evolutionary psychology, Homicide, in which they examined the high rates of violent death in nonstate societies and the decline in homicide from the Middle Ages to the present. In several of my previous books I cited those downward trends, together with humane developments such as the abolition of slavery, despotism, and cruel punishments in the history of the West, in support of the idea that moral progress is compatible with a biological approach to the human mind and an acknowledgment of the dark side of human nature. 3 I reiterated these observations in response to the annual question on the online forum www.edge.org, which in 2007 was “What Are You Optimistic About?” My squib provoked a flurry of correspondence from scholars in historical criminology and international studies who told me that the evidence for a historical reduction in violence is more extensive than I had realized.4 It was their data that convinced me that there was an underappreciated story waiting to be told.
My first and deepest thanks go to these scholars: Azar Gat, Joshua Goldstein, Manuel Eisner, Andrew Mack, John Mueller, and John Carter Wood. As I worked on the book, I also benefited from correspondence with Peter Brecke, Tara Cooper, Jack Levy, James Payne, and Randolph Roth. These generous researchers shared ideas, writings, and data and kindly guided me through fields of research that are far from my own specialization.
David Buss, Martin Daly, Rebecca Newberger Goldstein, David Haig, James Payne, Roslyn Pinker, Jennifer Sheehy-Skeffington, and Polly Wiessner read most or all of the first draft and offered immeasurably helpful advice and criticism. Also invaluable were comments on particular chapters offered by Peter Brecke, Daniel Chirot, Alan Fiske, Jonathan Gottschall, A. C. Grayling, Niall Ferguson, Graeme Garrard, Joshua Goldstein, Capt. Jack Hoban, Stephen Leblanc, Jack Levy, Andrew Mack, John Mueller, Charles Seife, Jim Sidanius, Michael Spagat, Richard Wrangham, and John Carter Wood.
Many other people responded to my inquiries with prompt explanations or offered suggestions that were incorporated into the book: John Archer, Scott Atran, Daniel Batson, Donald Brown, Lars-Erik Cederman, Christopher Chabris, Gregory Cochran, Leda Cosmides, Tove Dahl, Lloyd deMause, Jane Esberg, Alan Fiske, Dan Gardner, Pinchas Goldschmidt, Cmdr. Keith Gordon, Reid Hastie, Brian Hayes, Judith Rich Harris, Harold Herzog, Fabio Idrobo, Tom Jones, Maria Konnikova, Robert Kurzban, Gary Lafree, Tom Lehrer, Michael Macy, Steven Malby, Megan Marshall, Michael McCullough, Nathan Myhrvold, Mark Newman, Barbara Oakley, Robert Pinker, Susan Pinker, Ziad Obermeyer, David Pizarro, Tage Rai, David Ropeik, Bruce Russett, Scott Sagan, Ned Sahin, Aubrey Sheiham, Francis X. Shen, Lt. Col. Joseph Shusko, Richard Shweder, Thomas Sowell, Håvard Strand, Ilavenil Subbiah, Rebecca Sutherland, Philip Tetlock, Andreas Forø Tollefsen, James Tucker, Staffan Ulfstrand, Jeffrey Watumull, Robert Whiston, Matthew White, Maj. Michael Wiesenfeld, and David Wolpe.
Many colleagues and students at Harvard have been generous with their expertise, including Mahzarin Banaji, Robert Darnton, Alan Dershowitz, James Engell, Nancy Etcoff, Drew Faust, Benjamin Friedman, Daniel Gilbert, Edward Glaeser, Omar Sultan Haque, Marc Hauser, James Lee, Bay McCulloch, Richard McNally, Michael Mitzenmacher, Orlando Patterson, Leah Price, David Rand, Robert Sampson, Steve Shavell, Lawrence Summers, Kyle Thomas, Justin Vincent, Felix Warneken, and Daniel Wegner.
Special thanks go to the researchers who have worked with me on the data reported in these pages. Brian Atwood carried out countless statistical analyses and database searches with precision, thoroughness, and insight. William Kowalsky discovered many pertinent findings from the world of public opinion polling. Jean-Baptiste Michel helped develop the Bookworm program, the Google Ngram Viewer, and the Google Books corpus and devised an ingenious model for the distribution of the magnitude of wars. Bennett Haselton carried out an informative study of people’s perceptions of the history of violence. Esther Snyder assisted with graphing and bi
bliographic searches. Ilavenil Subbiah designed the elegant graphs and maps, and over the years has provided me with invaluable insight about the culture and history of Asia.
John Brockman, my literary agent, posed the question that led to the writing of this book and offered many helpful comments on the first draft. Wendy Wolf, my editor at Penguin, offered a detailed analysis of the first draft that did much to shape the final version. I’m enormously grateful to John and Wendy, together with Will Goodlad at Penguin UK, for their support of the book at every stage.
Heartfelt thanks go to my family for their love and encouragement: Harry, Roslyn, Susan, Martin, Robert, and Kris. My greatest appreciation goes to Rebecca Newberger Goldstein, who not only improved the book’s substance and style but encouraged me with her belief in the value of the project, and who has done more than anyone to shape my worldview. This book is dedicated to my niece, nephews, and stepdaughters: may they enjoy a world in which the decline of violence continues.
1
A FOREIGN COUNTRY
The past is a foreign country: they do things differently there.
—L. P. Hartley
If the past is a foreign country, it is a shockingly violent one. It is easy to forget how dangerous life used to be, how deeply brutality was once woven into the fabric of daily existence. Cultural memory pacifies the past, leaving us with pale souvenirs whose bloody origins have been bleached away. A woman donning a cross seldom reflects that this instrument of torture was a common punishment in the ancient world; nor does a person who speaks of a whipping boy ponder the old practice of flogging an innocent child in place of a misbehaving prince. We are surrounded by signs of the depravity of our ancestors’ way of life, but we are barely aware of them. Just as travel broadens the mind, a literal-minded tour of our cultural heritage can awaken us to how differently they did things in the past.