In the 1970s, Daniel Kahneman persuaded officials at Israel’s Ministry of Education that high schools should teach judgment and decision making. He put together a team to design the course and write its textbook: several experienced teachers, some of his psychology students, and Seymour Fox, dean of the Hebrew University’s School of Education and an expert in building curricula.
They met every Friday afternoon for about a year. By then they had a detailed outline, a couple of chapters and a few trial lessons. Everyone felt the work was going well.
One afternoon, while the team was discussing how to estimate uncertain quantities, Kahneman tried an exercise on the team itself. Each person wrote down, privately, how long it would take to hand the ministry a finished draft. He collected the slips and wrote the answers on the blackboard. They clustered around two years. The lowest was a year and a half, the highest two and a half.
Then he turned to Fox and asked about other teams that had built a curriculum from scratch. Fox knew several in detail. How much longer, Kahneman asked, had they needed from the point his own team had reached?
Fox fell silent. When he answered, by Kahneman’s account he seemed to be blushing. “You know, I never realized this before, but in fact not all the teams at a stage comparable to ours ever did complete their task.” About 40 percent, he estimated, never finished.
Kahneman asked about the teams that did finish. “I cannot think of any group that finished in less than seven years,” Fox said, “nor any that took more than ten.”
Kahneman grasped at one last hope and asked how their team compared with the others. Fox didn’t hesitate long. “We’re below average,” he said, “but not by much.”
Fox’s own estimate on the blackboard had sat comfortably inside the group’s optimism. Until Kahneman asked, Fox had never connected what he knew about other teams with his forecast for this one.
“We should have quit that day,” Kahneman wrote decades later. Nobody wanted six more years on a project with a 40 percent chance of failing. Yet after a few minutes of half-hearted debate, the team carried on as if nothing had happened.
The book was finished eight years later. Kahneman had long since left the team and was no longer living in Israel. The ministry’s enthusiasm had faded, and the textbook was never used.
Kahneman later called the episode one of the most instructive experiences of his professional life. He and Amos Tversky gave its lesson a name: the inside view, which forecasts from the plan in front of you, and the outside view, which starts from what happened to others who tried the same thing. Kahneman added a caution of his own. That the outside view was so spectacularly right this time, he wrote, was surely a fluke.