Enlightenment Now: The Case for Reason, Science, Humanism, and Progress

Resisters of scientific thinking often object that some things just can’t be quantified. Yet unless they are willing to speak only of issues that are black or white and to foreswear using the words more, less, better, and worse (and for that matter the suffix –er), they are making claims that are inherently quantitative. If they veto the possibility of putting numbers to them, they are saying, “Trust my intuition.” But if there’s one thing we know about cognition, it’s that people (including experts) are arrogantly overconfident about their intuition. In 1954 Paul Meehl stunned his fellow psychologists by showing that simple actuarial formulas outperform expert judgment in predicting psychiatric classifications, suicide attempts, school and job performance, lies, crime, medical diagnoses, and pretty much any other outcome in which accuracy can be judged at all. Meehl’s work inspired Tversky and Kahneman’s discoveries on cognitive biases and Tetlock’s forecasting tournaments, and his conclusion about the superiority of statistical to intuitive judgment is now recognized as one of the most robust findings in the history of psychology.⁴⁷

Like all good things, data are not a panacea, a silver bullet, a magic bullet, or a one-size-fits-all solution. All the money in the world could not pay for randomized controlled trials to settle every question that occurs to us. Human beings will always be in the loop to decide which data to gather and how to analyze and interpret them. The first attempts to quantify a concept are always crude, and even the best ones allow probabilistic rather than perfect understanding. Nonetheless, quantitative social scientists have laid out criteria for evaluating and improving measurements, and the critical comparison is not whether a measure is perfect but whether it is better than the judgment of an expert, critic, interviewer, clinician, judge, or maven. That turns out to be a low bar.

Because the cultures of politics and journalism are largely innocent of the scientific mindset, questions with massive consequences for life and death are answered by methods that we know lead to error, such as anecdotes, headlines, rhetoric, and what engineers call HiPPO (highest-paid person’s opinion). We have already seen some dangerous misconceptions that arise from this statistical obtuseness. People think that crime and war are spinning out of control, though homicides and battle deaths are going down, not up. They think that Islamist terrorism is a major risk to life and limb, whereas the danger is smaller than that from wasps and bees. They think that ISIS threatens the existence or survival of the United States, whereas terrorist movements rarely achieve any of their strategic aims.

The dataphobic mindset (“It’s not like that in Burkina Faso”) can lead to real tragedy. Many political commentators can recall a failure of peacekeeping forces (such as in Bosnia in 1995) and conclude that they are a waste of money and manpower. But when a peacekeeping force is successful, nothing photogenic happens, and it fails to make the news. In her book Does Peacekeeping Work? the political scientist Virginia Page Fortna addressed the question in her title with the methods of science rather than headlines, and, in defiance of Betteridge’s Law, found that the answer is “a clear and resounding yes.” Other studies have come to the same conclusion.⁴⁸ Knowing the results of these analyses could make the difference between an international organization helping to bring peace to a country and letting it fester in civil war.

Do multiethnic regions harbor “ancient hatreds” that can only be tamed by partitioning them into ethnic enclaves and cleansing the minorities from each one? Whenever ethnic neighbors go for each other’s throats we read about it, but what about the neighborhoods that never make the news because they live in boring peace? What proportion of pairs of ethnic neighbors coexist without violence? The answer is, most of them: 95 percent of the neighbors in the former Soviet Union, 99 percent of those in Africa.⁴⁹

Do campaigns of nonviolent resistance work? Many people believe that Gandhi and Martin Luther King just got lucky: their movements tugged at the heartstrings of enlightened democracies at opportune moments, but everywhere else, oppressed people need violence to get out from under a dictator’s boot. The political scientists Erica Chenoweth and Maria Stephan assembled a dataset of political resistance movements across the world between 1900 and 2006 and discovered that three-quarters of the nonviolent resistance movements succeeded, compared with only a third of the violent ones.⁵⁰ Gandhi and King were right, but without data, you would never know it.