Daniel Kahneman in Edge:
I'll start with a topic that is called an inside-outside view of the planning fallacy. And it starts with a personal story, which is a true story.
Well over 30 years ago I was in Israel, already working on judgment and decision making, and the idea came up to write a curriculum to teach judgment and decision making in high schools without mathematics. I put together a group of people that included some experienced teachers and some assistants, as well as the Dean of the School of Education at the time, who was a curriculum expert. We worked on writing the textbook as a group for about a year, and it was going pretty well—we had written a couple of chapters, we had given a couple of sample lessons. There was a great sense that we were making progress. We used to meet every Friday afternoon, and one day we had been talking about how to elicit information from groups and how to think about the future, and so I said, Let's see howwe think about the future.
I asked everybody to write down on a slip of paper his or her estimate of the date on which we would hand the draft of the book over to the Ministry of Education. That by itself by the way was something that we had learned: you don't want to start by discussing something, you want to start by eliciting as many different opinions as possible, which you then you pool. So everybody did that, and we were really quite narrowly centered around two years; the range of estimates that people had—including myself and the Dean of the School of Education—was between 18 months and two and a half years.
But then something else occurred to me, and I asked the Dean of Education of the school whether he could think of other groups similar to our group that had been involved in developing a curriculum where no curriculum had existed before. At that period—I think it was the early 70s—there was a lot of activity in the biology curriculum, and in mathematics, and so he said, yes, he could think of quite a few. I asked him whether he knew specifically about these groups and he said there were quite a few of them about which he knew a lot. So I asked him to imagine them, thinking back to when they were at about the same state of progress we had reached, after which I asked the obvious question—how long did it take them to finish?