Steven Pinker has read the reports on civilian deaths in the Afghan war, mass rapes in the Congo, “going postal” shootings in the United States, and our youths’ seeming addiction to Call of Duty video games. Yet the Harvard cognitive scientist and wildly effective popularizer of evolutionary psychology brings you the Good News: humans are now far less violent than they have ever been. In roughly 700 pages of text and many dozens of graphs, Pinker’s The Better Angels of Our Nature takes us on a long trip through millennia of brutality and sadism to arrive at a time, our time, when we ain’t going to study war—nor, for that matter, wife-beating, animal torture, or burning at the stake—no more.

Professional historians have known this news for decades; in their field, it is conventional wisdom that violence has declined over the centuries in both rate and savagery. Now Pinker brings his considerable analytical powers and rhetorical skills to tell this story to the wider public. He can be heard on NPR, seen on The Colbert Report, and read about in New York Times features. The Times’s Nicholas Kristof is ready to award The Better Angels of Our Nature a Pulitzer. Unlike the historians, many lay readers and listeners are surprised. “Really?!” Stephen Colbert asked in one of his less parodic moments. Really.

Pinker also means to deliver on the book’s subtitle, “Why Violence Has Declined.” But while his chronicle is powerfully and convincingly straightforward—rates of violence have indeed decreased—his explanations are less so. They may even undermine his campaign for a biological view of the human condition.

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The Better Angels of Our Nature is, for the most part, a grand museum of humans wreaking havoc on one another, with exhibits ranging from genocides and mass warfare, to child sacrifice and ingenious tortures, to homophobia and schoolyard bullying. Pinker is an engaging docent. He explains the exhibits, anticipates our questions, and livens up the didactic material with anecdotes and allusions to popular culture. Given the length of the tour and the many depressing displays, we can be thankful for our guide’s skills.

At the start, Pinker stipulates that we are to think of violence in terms of rates, as deaths or injuries per population. The modern world seems intensely violent in absolute terms—World War II alone killed more people than were alive in 1000 B.C.—but our attention should be on the risk of being a victim or victimizer. The rates and risks of violence have plummeted.

Thousands of years ago, members of small tribal societies were at least five times more likely to die in war than are modern humans. Similarly, the rate of death from domestic homicide was at least five times that of the contemporary United States. Physical anthropologists have unearthed many a prehistoric skeleton with a bashed-in skull, and cultural anthropologists have watched many of the world’s remaining hunter-gatherers fight one another. The rise of what Pinker calls “Leviathans”—from petty chiefdoms, ancient empires, and feudal monarchies to modern nations—pacified the violent anarchy of the early world. Although governments fight one another, they insist on controlling the means of violence and abhor internal conflict, so they suppress bloodshed, at least when committed by others.

Pinker next focuses our attention on Europe in the last millennium, which provides relatively “hard” data on homicides and other crimes. Medieval Europeans faced homicide rates ten to one hundred times greater than today’s Europeans do. The medievals also experienced a wide variety of state violence perpetrated against dissidents, criminals, and religious heretics. Pinker dwells on the brutality, such as burning and disemboweling, and he wonders at the entertainment people found in public torture. He quotes a 1660 passage from the diary of Samuel Pepys in which the English parliamentarian jokes about watching a “Major-general Harrison hanged, drawn, and quartered” and describes the London onlookers’ “great shouts of joy” upon being shown Harrison’s head and heart. In the same paragraph, Pepys relates meeting friends for an oyster dinner. Pinker also reports of French villages that, lacking a criminal to execute publicly, would buy one from a neighboring town. These scenes eventually came to inspire revulsion and were ammunition for eighteenth-century humanitarians whose reforms curtailed much of the state-sponsored or -condoned violence in the West (although more slowly in the Americas). By the 1800s judicial torture, inquisitions, witch burning, executions for minor crimes, and slavery were ended.

The medieval and early-modern periods now out of the way, Pinker turns to the second half of the twentieth century with its “Long Peace” between great powers and then its “New Peace” around the globe. Statistical studies show that wars and atrocities have become much rarer and proportionally less destructive over the last two thousand years. The path to a more peaceful world has not been smooth; it was interrupted by a surge in the lethality of weapons, the emergence of messianic political movements, and more recently by decolonization in developing nations. Still, by our time, large-scale wars among big powers have mostly disappeared. Even terrorism has declined in recent decades.

Pinker reports of medieval French villages that would buy criminals to execute publicly.

But, you ask, what about the two world wars? They are among the twenty deadliest conflicts, per capita, in human history, albeit far behind the An Lushan Revolt in eighth-century China and the thirteenth-century Mongol Conquests. The New Yorker’s Elizabeth Kolbert points out that the world wars took place in much less time than those other cases, so perhaps there is a fudge here. Pinker addresses your question. He spends several pages describing the world wars in terms of a Poisson process with a non-stationary probability—don’t ask—in effect saying that they were random fluctuations in what is otherwise a clear trend away from war.

The final stop on the tour is the postwar expansion of human rights protections for individuals, particularly the vulnerable such as minorities, women, and children. Lynchings, rapes, caning of children, and abortions are down; so is racism, sexism, and homophobia. Up are explicit protections, even for laboratory and farm animals. We have arrived at a vegan sensibility.

Pinker is a terrific guide, but his pet peeves become obvious and annoying. His antipathy toward the Abrahamic religions is more than a peeve; he describes them as the source of numerous evils, from murder—“The Bible is one long celebration of violence”—to “benign hypocrisy.” (In one of his other roles, Pinker is an atheist activist.) He treats Marxism as an evil almost on par. He repeatedly makes digs at leftish intellectuals who might romanticize a pre-modern past or doubt a biological view of history. And he snorts at political correctness, which he interprets as the exaggerating of peaceful trends into foolishness, for example, banning dodge ball in school.

Tour done and pet peeves aside, we are ready to believe that people nowadays are vastly safer from and more repelled by violence than ever before. How did this happen?

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Pinker makes three strategic moves in explaining the drop in violence. First, he considers every kind of violence—even metaphoric violence, such as racist attitudes—as a single entity. Thus, he needs all expressions of violence, from genocide to spanking, to decline, and all of these declines need to follow a common story line. A more timid author might have been satisfied with explaining just the decline of, say, war. And a more timid author might worry that a nuclear exchange between India and Pakistan would destroy the whole analysis overnight.

Second, Pinker takes on the burden of explaining every fluctuation and nuance in violence trends. He doesn’t let a jitter in his graph line go as random noise. The notable exception seems to be those two quasi-random world wars. Yet, elsewhere, he cannot help but try to make sense of each with ad hoc accounts, for instance by digging into Hitler’s personality. Total explanation is a heavy task.

Third, Pinker tries to sweep together virtually every explanation for violence or peace that anyone has ever proposed—and more—including schooling, brain lesions, humanitarianism, secularism, feminization, codes of honor, commerce, book publishing, and even the Great Man Theory of history (Hitler, Stalin, Mao). Some explanations he dismisses—for example, that affluence reduced the motives for violence, that nuclear weapons ended large-scale war, and that Roe v. Wade lowered crime rates in America. But his remaining list of explanations is long and eclectic.

Out of this miscellany, however, emerge a few major themes. Pinker’s great drivers of violence are Hobbesian anarchy, which leads people to engage in personal retribution and violent deterrence; grand ideologies that demand total submission to a utopian vision, notably the Abrahamic religions and Marxism; and political tyrannies. Largely responsible for taming violence were the emergence of states, especially democracies; secular humanism, which values saving lives rather than souls; and the rationality—science, reason, intelligence—of modern life.

To flesh out this account, Pinker relies heavily on a sociologist, the German Jewish refugee Norbert Elias. In The Civilizing Process (1939), Elias argues that medieval rulers, eager to keep order in their domains, suppressed vassals’ inclinations to fight one another. Courtly rules of self-restraint, ranging from requirements that knives be sheathed to etiquettes of politeness, became elaborated and spread to the bourgeoisie and beyond. Such rules evolved into deep habits of controlling impulses, and eventually adults felt that violent outbursts were as humiliating as, say, losing sphincter control in public. The concurrent development of “gentle commerce” encouraged people to see things through the eyes of others. To trade and contract successfully, one must see the deal through the trade partner’s eyes; “a free market puts a premium on empathy.” Such empathy, in turn, inhibits violence.

To explain further declines in violence, Pinker emphasizes the Enlightenment, by which he means social contract theories that put human deliberation at the center of history, classic liberal individualism, the spread of literacy, and skepticism about revelation. The emergence of secular humanism increased the value westerners placed on individual lives, their will to limit authority, and their capacity for empathy. At a couple of junctures, Pinker highlights reading fiction as central to how modern people learned to empathize—think of Uncle Tom’s Cabin.

Pinker argues that fading religiousity reduced violence. But the drop in the United States coincided with growing Christianization.

Above all, Pinker credits the rise of reason. Especially in the last century, scientific learning has elevated people’s abilities to reason; people have literally gotten more intelligent. This last claim refers to the “Flynn Effect,” the increase in IQ scores over the last few generations around the world. Analytic intelligence necessarily reduces inclinations to violence. “Once [reason] is programmed with a basic self-interest and an ability to communicate with others, its own logic will impel it, in the fullness of time, to respect the interests of ever-increasing numbers of others.” If his argument implies that our great-grandparents were morally, as well as intellectually, “retarded,” so be it, Pinker says.

Historians of violence would generally say that, in their broad strokes, these explanations are probably (government and the civilizing process), possibly (humanism), and questionably (reason) correct.

Yet, if one looks closely, the explanations appear much murkier. Quick examples: Pinker argues that fading religiosity reduced violence. Yet, in the American case, the decline of violence from the nation’s founding to the 1950s coincides with growing Christianization. During this period, most Americans turned from folk and occult versions of religion to mainstream Christianity and became increasingly “churched.” And Pinker at one point explicitly rejects growing affluence as an explanation for pacification, but about 400 pages later he suggests that improved nutrition, clearly a byproduct of affluence, plumped up the frontal lobes of people’s brains, enabling greater self-control over violent impulses.

Going a little deeper, Pinker tries to explain away one of the best-known deviations in the pacification trend: the surge in criminal violence in the United States from the late 1960s to the 1990s. He describes it as a brief episode of “decivilizing,” a collective loss of self-control brought on by an indulgent culture of sex, drugs, and rock music. Hippie guru Jerry Rubin’s book Do It—not to mention Abbie Hoffman’s Steal This Book—and Bob Dylan’s lyric “I ain’t gonna work on Maggie’s farm no more” illustrate a cultural wave that encouraged young people to unleash their impulses. (Presumably the ’50s culture of Rebel Without a Cause and early rock n’ roll somehow correspond with a drop in violent crime.) Pinker knows that youth in the black ghettoes, where the late ’60s crime wave emerged, neither read Rubin nor listened to Dylan; they were not hippies. So, the connection he makes is that a middle-class loss of discipline encouraged legislators, judges, and cops to go easy on criminals, fueling the surge of violence. A generation later the civilizing process restarted, brought sterner law enforcement, and thus brought violence down, even in the face of gangsta rap and Lady Gaga.

If you find this account strained, know that most criminologists would share that sentiment. The surge and then abatement of violent crime remains perplexing to them. The best bet is that the upswing resulted from a confluence of structural factors—a glut of baby-boom teenagers and the loss of jobs in inner cities, which sent many men away from their families and into the drug trade and more mothers out to work—together with some cultural shifts. The latter more likely involved black youths’ greater sense of liberation rather than white youths’ flirtations with the counter culture. Once the violence started, imitation probably also played a role. The downswing, criminologists suggest, resulted from the aging of baby boomers, stronger law enforcement, merciless imprisonment, more jobs in the 1990s, and perhaps an exhaustion of the earlier cultural trends.

Pinker’s grandest explanation and deepest flaws concern reason. He argues that more reading, science, and learning reduced the inclination toward and tolerance for violence. There are a few problems with this.

True, educated people are less often the perpetrators or the victims of interpersonal violence, but they are not necessarily less inclined to violence, per se. For example, better-educated Americans were likelier than other Americans to support entry into World War II, escalation in Vietnam, and the pursuit of several subsequent American wars. And how would the eighteenth- and nineteenth-century rise in reading fiction have depressed violence when the new readers were disproportionately well-off women rather than poor men, who were most likely to be violent?

On the issue of science as pacifier, Pinker anticipates that a critic would point to Nazi science, and he answers that the Nazis were only pseudo-scientists; they were really folk romantics like other utopian killers. Maybe, but the people who raised the Nazis to power, followed their orders, and only twenty years before had supported the Kaiser’s war were at the apex of twentieth-century science, scholarship, and reason.

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Pinker the psychologist brings psychology into the explanation most explicitly in chapters entitled “Inner Demons” and “Better Angels,” which call to mind cartoon devils and angels whispering in each ear. However, unlike the cartoon devils and angels, the brain’s “faculties” do not press individuals to commit or to renounce violence. They are neural capacities or mechanisms that enable impulses for good or ill. They are not causes—and thus not the explanations—of violence, but are means of violence. This observation brings us to the question of human nature.

It is hard to imagine a greater change in human nature than the one Pinker presents. He convinces us that in the last millennia or two, a brief period in human development, the typical person’s chance of murdering and being murdered decreased dramatically. Rather than enjoying the sight of entrails being slowly torn from a victim’s body, ordinary people of today are unlikely ever to witness or experience lethal violence. We’re upset by the wails of a cat up a tree.

In this story, reason plays only a supporting role. And the brain is merely the stage upon which the plot unfolds.

Yet Pinker is a famous advocate for biological understandings of the mind and for evolutionary psychology, which insists that human nature was formed millions of years ago and that we moderns are still ruled by that nature. For example, obesity can be explained by eating instincts evolved in the Pleistocene, which are now harmful in a fast-food world. How can he reconcile his advocacy with his Good News?

Pinker briefly entertains but then wisely dismisses the possibility that natural selection over mere centuries could have sufficiently “retuned” human nature. He insists, nonetheless, that “moral progress is compatible with a biological approach to the human mind.” He argues that the “increased engagement over time” of “faculties that steer us away from violence”—such as the secretion of oxytocin and the executive function of the frontal lobe—“can be credited for declines in violence.” Note the largely instrumental role he gives such faculties in these and similar passages. In essence Pinker is saying that evolution has made the human brain capable of enacting violence and capable of restraining violence. What kind of explanation is that for the vast transformation he describes?

My car’s gas pedal and braking system make me capable of driving from one place to another. A malfunction in these or in other systems could suddenly reroute me into a tree. In one sense, then, the car’s “faculties” steer me from my house to my office. But it is a trivial part of the explanation for why I go to work. Similarly, the brain’s faculties, however essential to the process, do not really explain why the human race steered away from violence, why we left the coliseums of brutal torture and showed up at church potlucks for victims of domestic abuse.

Thus, psychological, biological, and evolutionary developments do not explain what brought humans to peace. Pinker’s real answer to why violence has declined relies largely on the development of new ideas: philosophies, values, norms, education, skepticism, sentimentality, culture—the “soft” stuff. Ideas and feelings, in Pinker’s account, are strong enough to have overridden even genetic pressures, such as the reproductive value men gain in raping women.

Most historians agree that cultural factors were critical in reducing interpersonal violence, but would stress structural development much more than Pinker does. (Most would also set aside interstate war as a separate phenomenon, driven by different forces and less certainly curbed.) The emergence of ever-larger governments is the most important structural factor. Though he talks of leviathans, Pinker doesn’t give them enough credit. Authorities squash warlords; protect commerce; replace feuding with some sort of law; and put rowdy boys into schools, workplaces, and even armies, all of which train, discipline, and generally instill restraint. That people usually prefer even tyrannical regimes to social disorder testifies to how much we value government, any government.

Pinker does well to emphasize the West’s individualism, which over the course of time sanctified the integrity of the separate person. After all, if someone is culturally defined as an interchangeable part of a clan or tribe, as was true in most of human history, his or her life and suffering matter less. But this individualism did not arise full-blown from the minds of seventeenth- and eighteenth-century sages; the Enlightenment was one step in a millennia-long process of religious and political development. And the Enlightenment is not just a cultural phenomenon. It was enabled by structural changes. Improving material conditions enabled physical, economic, and political security, which allowed, or perhaps even generated, the luxury of tender sensibilities and the widening circle of sympathetic concern that emerged among the nineteenth-century bourgeoisie.

In this story Pinker’s grand reason plays only a supporting role. And the biological apparatus of the brain is merely the stage upon which the plot unfolds.

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Even if we don’t fully understand the reasons for the decline in rates of violence, the decline is real, and Pinker describes it vividly and lucidly. He nonetheless worries, as well he should, that his audience will not remember this Good News. Some parts of it have been told before. For instance, a commission appointed by Lyndon Johnson to explain the civil disorders of the 1960s reported that violence in the United States had dropped greatly over the course of its history. Though noted by the media at the time, that information was soon forgotten, and so the surprise on Pinker’s book tour.

Pinker mainly blames this amnesia on “the innumeracy of our journalistic and intellectual culture,” although he also quotes David Hume: “The humour of blaming the present, and admiring the past, is strongly rooted in human nature.” I’m no more sure of the rootedness of this “humour” in human nature than of the rootedness of sadism in human nature. But there may be something in our modern intellectual heritage that frames the present in terms of a fall from grace. If indeed we are innumerate or just pessimistic about our own time, there will be a market for another surprising book on the decline of violence in a decade or two—assuming the decline continues.