Make money, not war: Steven Pinker's The Better Angels of Our Nature: Why Violence Has Declined.

• Author: De Wolf, Aschwin
• Position: Book review

Steven Pinker's The Better Angels of Our Nature: Why Violence Has Declined (New York: Viking Adult, 2011) is one of the most ambitious contributions to social science produced to date. In this heavily referenced, small-print tome of more than seven hundred pages, Pinker seeks not only to demonstrate that human violence has declined substantially throughout human history but also to identify the reasons for this decline. In addition, his treatment of the sociobiology of violence might itself constitute a stand-alone work on this important topic. Not even a lengthy review essay can do justice to such an ambitious work. I confine myself here for the most part to highlighting its many strengths and some of its weaknesses from a classical-liberal perspective.

Pinker's thesis is easy to summarize. In spite of the gloom and doom that attend current intellectual discourse, the world has become a much more peaceful place, and we are living in the most peaceful period in mankind's history. This decline in violence is not a stand-alone phenomenon; it has coincided with a movement toward equal treatment of people of all races, women, children, and gays and even toward more considerate treatment of animals.

Much to the chagrin of the "anthropologists of peace," Pinker provides persuasive evidence that premodern humans were anything but peaceful. For example, he notes that war-associated cannibalism may have been so widespread that it has given us genes that protect us against cannibalism-mediated prion diseases. What might be gained by portraying premodern humans and modern hunter-gatherers (and even chimpanzees) as inherently peaceful is unclear, but such a portrayal may be important for politically motivated scientists who seek to discredit modern Western culture and seek funding for pet political projects.

A more credible and understandable challenge is that the carnage and genocide that the Communists and National Socialists inflicted during the twentieth century render optimism about a decline in violence moot, if not perverse. Pinker is not insensitive to the collectivist horrors that plagued the past century, but he presents sobering evidence that "total war" and genocide are far from rare in human history and were frequently a source of pride and celebration, not shame. Adjusting for increased population size, the death toll of World War II ranks ninth among history's worst documented atrocities. Thus, the twentieth-century outbursts of violence and murder did not reverse the overall trend toward less violence. In the late twentieth century and the post-Cold War period in particular, the continuing decline in violence seems almost surreal by historical standards, as the number of great wars and the killing power of each war declined--a phenomenon Pinker calls the "Long Peace." To grasp the breathtaking nature of this Long Peace, consider the following statistics from Pinker's book:

Use of nuclear weapons since 1945: zero

Number of direct confrontations between the two Cold War superpowers on the battlefield: zero

Number of times the great powers have fought each other since 1953: zero

Interstate wars between western European countries since World War II: zero

Interstate wars between major developed countries since 1945: zero

Expansions of territory by developed countries since the late 1940s: zero

Number of internationally recognized states that have gone out of existence through conquest since World War II: zero

Pinker takes care to point out that "there is no law of Conservation of Violence" (p. 252) in which the decline of violence in one part of the world is offset by the increase in other parts in the world. Despite regional differences in violence, the general trend has been a reduction all over the world.

This fact raises an important question: Why has violence declined? For Pinker, the prevalence of aggression in the rest of the animal world (which most of us take for granted) and mankind's violent history should prompt us to ask not "Why is there war?" but "Why is there peace?" Consideration of the latter question brings us to the difficult, complicated part of the book. Pinker takes us through human history to show how not only violence but also our perception, endorsement, and tolerance of it have progressively declined. Things that strike us as horribly barbaric today, such as the public enjoyment of extreme torture and the annihilation of an entire population, were not unusual for our species in the past.

One challenge in identifying the causes of the remarkable declines in violence and cruelty is that we must take care not to attribute them to the advent of more peaceful dispositions. As Pinker so eloquently puts it, "[T]he challenge is to find an exogenous change that precedes the change in sensibilities and behavior so we can avoid the circularity of saying that people stopped doing cruel things because they got less cruel" (p. 169). He resists explaining the decline of violence according to a single unified perspective and instead identifies a number of reasons. I focus here on three causes of the decline in violence: gentle commerce, reason, and Leviathan.

Gentle Commerce

That commerce fosters peace is almost self-evident to classical-liberal writers and many economists. Capitalism substitutes trade for force, encourages empathy by placing individuals in the position of (potential) customers ("a free market puts a premium on empathy" [p. 77]), encourages amity between citizens of trading nations, and puts a premium on the use and development of reason by encouraging proportional and probabilistic thinking. Moreover, capitalism, unlike socialism, can also incorporate some of our "darker" traits, such as competitiveness and status seeking, without leading people into messy fights. "In a world in which wealth grows out of exchange, credit, and a division of labor, conquest cannot make a conqueror richer" (p. 245), writes Pinker.

One reason why it is so difficult for many people to recognize and celebrate these aspects of commerce is that humans spent most of their history in an environment characterized by predation and zero-sum game transactions and by the associated idea that one person's gain entails another person's loss. Pinker also singles out religion (notably medieval Christianity) for its hostility to commerce and moneylending. This hostility lessened over the centuries, but it returned with the rise of socialism and communism, and the anticapitalist mindset remains a dominant force among today's academics, politicians, and public officials.

One credible reason why the rise of commerce is a strong candidate for explaining the decline of violence is that capitalism did not need a deliberate collective decision or a change of human nature to emerge. As soon as a group of premodern humans stumbled on the possibility of agriculture and made a transition to permanent settlement, surplus could be traded with other humans, and the incentive to seek status through accumulation of wealth instead of through murder and mayhem could take root. Of course, such a development did not produce instantaneous peace across the board, but ongoing mutual adjustment between individuals and groups tipped the balance toward cooperation and may even have produced a situation in which using violence to further one's interests became the worst option for everyone except a psychopath. One important ingredient to perfect this transition from poverty and force to wealth and peace is the exercise of reason.

Reason and Evolution

If Pinker privileges one cause for the decline in violence, it is the exercise of reason. To posit reason as a driver, one needs to demonstrate either that certain exogenous events can trigger a rise in the deployment of this facility or that humans have become smarter. Pinker is sympathetic to both perspectives. As noted previously, a random event such as the discovery of agriculture can trigger permanent settlement and start a process that confers greater rewards on rational decision making, thereby establishing a positive-feedback loop.

Pinker discusses the "Flynn effect"--a sustained increase in intelligence test scores among all populations--as a driver of the decline of violence. He reviews various explanations of this effect and looks favorably on the idea that exposure to a more stimulating, scientific environment can trigger improved abstract reasoning. One does not have to agree with Pinker's interpretation of the Flynn effect to recognize that, as a general rule, increased intelligence favors nonviolent resolution of conflict and forms of social organization that value autonomy. The data that Pinker presents demonstrate that this relationship remains robust after one controls for other variables. He further observes that the overwhelming majority of homicides and violent crimes are committed by people in the lowest socioeconomic classes.

In one of the book's weaker sections, Pinker considers the idea that the decline of violence (or rise in intelligence) might be the result of ongoing natural selection. More and more scholars are presenting genetic evidence that evolution did not stop when modern humans left Africa, and they have identified events that might have triggered and accelerated human evolution. Pinker cannot but confirm these findings, and his extensive treatment of the neurobiological basis of violence also forces him to recognize the heritability of aggressive tendencies, but he shows little interest in exploring natural selection as an explanation of the decline in violence, despite its potential for allowing rigorous treatment.

He calls Gregory Cochran and Henry Harpending's seminal book The 10,000 Year Explosion: How Civilization Accelerated Human Evolution (2009) a "manifesto" and notes that none of the genes that have been identified have been implicated in behavior. I doubt that this argument can be dismissed so easily, however, and Pinker does not do...