Why it’s so hard to make predictions—and how we can get better at it.
Marco Visscher | December 2011 Issue
Paul Ehrlich looked at the numbers and started to worry. At the turn of the 19th century, there were a billion people on Earth. In 1927, there were 2 billion. In 1960, 3 billion. The next billion would be ticked off during the 1970s. Meanwhile, people suffered from hunger in large parts of the world, and the environment was at risk.
What a disaster, thought Ehrlich, a young biology professor at Stanford University in Palo Alto, California. He wrote The Population Bomb in 1968. It was impossible to increase food production enough to feed a growing world population, he said. “We will not be able to prevent large-scale famines in the next decade or so.” He wrote about the inevitability of declining health, economic crises, ecological destruction and lengthy wars—and that was his “optimistic” scenario.
None of that has come to pass. We’re still here. Too many people still die from hunger, but fewer than before, and definitely not because worldwide food production is insufficient. The world economy had blossomed within a generation of Ehrlich’s book; poverty and hunger were being fought more effectively than ever. People everywhere were healthier and living longer, while in rich countries nature was recovering and the environment was becoming cleaner and the world more peaceful. None of what Ehrlich predicted has come true.
Fortunately for us, Ehrlich failed hopelessly at predicting the future. Less rosy is the fact that he’s far from alone in failing. It appears we are all terrible fortune-tellers.
Despite our consistent mistakes, we keep making predictions and listening to those of others, especially those who seem worst at it: experts who earn their living making them.
Is there nothing we can learn from our mistakes? Can we learn to improve our predictions and better evaluate those of others? The good news: Yes, we can. The bad news: It isn’t easy.
“If I could predict the future perfectly, we wouldn’t be sitting here eating lunch together,” Ehrlich jokes in a crowded cafeteria on the Stanford campus as he looks back on The Population Bomb, a book that’s garnering increased interest as more people grow uneasy about passing the threshold of 7 billion global inhabitants. His youthful appearance and occasionally sparkling eyes make the towering, slim, gray-haired man seem as if he’s discovered the secret of eternal youth. It’s not hard to see why everyone—from colleagues to students—likes the amiable, somewhat formal Ehrlich. “We just do our best when we make predictions.”
“We” are indeed just ordinary mortals, so people afford “us” a margin of error. But is the same true of Ehrlich? He is one of the countless experts who write bestsellers, advise politicians and businessmen and are quoted in the media. Longitudinal studies show that these experts usually perform no better than well-informed laypeople, particularly when the experts are popular.
The festival of errors is not reserved for doomsayers. Open any 10-year-old popular science magazine: Where is the time machine? Where are the robots that were supposed to take over our household duties? And every new form of communication we invent—the telegraph, telephone, fax, radio, Internet—seduces us into predicting the arrival of world peace, for war will be unnecessary in a fully connected world. Optimism, it seems, is as blinding as pessimism.
Our deplorable record in predicting the future wouldn’t be so worrying if it didn’t constantly influence us. Politicians devise policy based on the expectations of scientific advisors. Company execs chart their five-year plans after well-compensated consultants explain what the market will do. Developers build new neighborhoods based on what demographers tell them. Television is crawling with experts happy to predict the outcome of tensions in distant nations, the way the economy is going to develop and what the climate will be like several decades from now. And each of us spends and invests our money based on our own vision of what the future holds.
The only comprehensive study into just how dismally experts fare was conducted by Philip Tetlock, a professor of psychology at the University of Pennsylvania, and it’s not pretty. Over a period of 20 years, he collected tens of thousands of predictions made by nearly 300 experts who earned their living as advisors on political and economic developments. He asked them questions such as these: Will there be a nonviolent end to apartheid in South Africa within 10 years? Will America wage war in the Persian Gulf in the next five years? Will the economy grow, shrink or remain the same next year? His conclusion is shocking. “Experts have a hard time beating a dart-throwing chimp,” says Tetlock. “It’s not the sort of victory you’re going to brag about.”
Yet we keep listening to the experts. Why? “The future is a swirling mass of uncertainty,” says Canadian journalist Dan Gardner, the author of Future Babble. “Because we’re very disturbed by uncertainty, we’re looking for answers, preferably ones that fit our preconceptions. And voilà, in the marketplace of ideas, we’re sure to find lots of experts who say what we want to hear.” We choose ironclad belief—which may be a mistake over resigning ourselves to uncertainty.
People like to look ahead. Fortune-tellers have been staring into crystal balls and reading tea leaves for thousands of years. Religions acknowledge prophetic dreams. Many fairy tales and legends contain characters with the gift of foreknowledge. In large cities, you can walk into 100 places and have your hand or Tarot cards read for you. We’re simply a curious species, and plenty of people present themselves to quench that thirst. That’s why we check the Monday morning paper for Saturday’s weather, even though the horoscope on the next page is probably more accurate.