The Undoing Project: A Friendship that Changed the World(84)

He and Amos wanted to avoid getting into an argument about the rationality of man. That argument would only distract people from the phenomenon they were uncovering. They preferred to reveal man’s nature, and let man decide what he was. Their next task, they saw, was to buff and polish “Value Theory” for publication. They both worried that someone would find an obvious contradiction—some Allais paradox–like observation that would render their theory dead on arrival. They’d spend three years doing very little else but searching the theory for internal contradictions. “In those three years we did not discuss anything of genuine interest,” said Danny. Danny’s interest ended with the psychological insights; Amos was obsessed with the business of using the insights to create a structure. What Amos saw, perhaps more clearly than Danny, was that the only way to force the world to grapple with their insights into human nature was to embed them in a theory. That theory needed to explain and predict behavior better than existing theory, but it also needed to be expressed in symbolic logic. “What made the theory important and what made it viable were completely different,” said Danny, years later. “Science is a conversation and you have to compete for the right to be heard. And the competition has its rules. And the rules, oddly enough, are that you are tested on formal theory.” After they finally sent a draft of their paper to the economics journal Econometrica, Danny was perplexed by the editor’s response. “I was kind of hoping he’d say, ‘Loss aversion is a really cool idea.’ He said, ‘No, I like the math.’ I was sort of shattered.”

By 1976, purely for marketing purposes, they changed their title to “Prospect Theory.” “The idea was to give the theory a completely distinct name that would have no associations whatsoever,” said Danny. “When you say ‘prospect theory,’ no one knows what you’re talking about. We thought: Who knows? It may turn out to be influential. And if it is we don’t want it to be confused with anything else.”

In all of this they were slowed, dramatically, by the turmoil in Danny’s life. By 1974 he’d moved out of his house and was living apart from his wife and children. A year later he left the marriage, and flew to London to meet the psychologist Anne Treisman to formally “declare my love.” She reciprocated. By the fall of 1975 Amos was clearly weary of the inevitable fallout. “It is hard to overestimate the amount of time and the amount of emotional and mental energy that is consumed with such affairs,” he wrote to his friend Paul Slovic.

In October 1975 Danny flew to England again, this time to see Anne in Cambridge and to travel with her to Paris. He was at once in a totally uncharacteristic state of elation and worried about the effect of his new relationship with Anne on his old one with Amos. In Paris he found waiting what appeared to be a letter from Amos—but, opening it, he at first found only a draft of what would become “Prospect Theory.” Danny took the absence of any personal note as a subtle message from Amos. Sitting with his new love in the world’s capital of romance, Danny sat down and wrote what amounted to a love letter: to Amos. “Dear Amos,” it began. “When I came to Paris I found an envelope from you. I pulled out your manuscript but there was no letter with it. And I told myself that Amos is very angry with me, and not without reason. After dinner, I was looking for a used envelope to send this back to you and I found your envelope, and then saw your letter inside. We were late for dinner and I just glanced to see how you finish it. And I saw the words ‘Yours, as ever’ and I had goose bumps from emotion.” He went on to write that he’d explained to Anne that he could never have achieved on his own what he had achieved with Amos, and that the new paper they were working on was yet another step. “This is for me the greatest moment in a relationship which I see as one of the peaks of my life,” he wrote. Then he added: “I was yesterday at Cambridge. And I spoke to them about our work on Value Theory. The enthusiasm is almost embarrassing. I concluded with a discussion of the early stages of the isolation effect. And they responded to that especially. In general, they gave me the feeling that I’m one of the world’s greats. They were trying so hard to impress me that I reached the conclusion that maybe the time has come for me to be free of the need to impress others.”

In some strange way, as they approached their moment of greatest public triumph, their collaboration remained a private affair, a gamble with no context. “As long as we stayed in Israel, the whole idea of what the world thought of us didn’t occur to us,” said Danny. “We benefited from our isolation.” That isolation depended on them being together, in the same room, behind a closed door.

That door was now cracking open. Anne was British. She was also a gentile and the mother of four children, one of whom had Down syndrome. There were about sixteen different reasons she couldn’t, or wouldn’t, move to Israel. And if Anne wasn’t moving to Israel, it followed that Danny would need to leave. Danny and Amos scrambled and found a temporary solution, in 1977, by heading off together from Hebrew University on sabbatical to Stanford University, where Anne might join them. But a few months after their arrival in the United States, Danny announced that he planned to marry Anne and stay. He forced Amos to make a decision about what to do about their relationship.

It was now Amos’s turn to sit down and write an emotional letter. Danny was messy, in a way that Amos could never be messy even if he wanted to be. Amos had wanted to be a poet when he was a boy. He’d wound up a scientist. Danny was a poet, who somehow happened to have become a scientist. Danny felt some obvious desire to be more like Amos; Amos, too, harbored some less obvious desire to be more like Danny. Amos was a genius. But he needed Danny, and he knew it. The letter Amos wrote was to his close friend Gidon Czapski, the rector of Hebrew University. “Dear Gidi,” it began. “The decision to remain here in the United States is the most difficult decision I have ever made. I cannot ignore my desire to bring to a completion, at least partially, the joint work with Danny. I just cannot accept the idea that the joint work of years could come to naught and that we will not be able to complete the ideas we have.” Amos went on to explain that he planned to accept a chaired professorship offered to him by Stanford University. He knew full well that everyone in Israel would be shocked and angry. “If Danny leaves Israel it is a personal tragedy,” a Hebrew University official had said to him not long before. “If you leave it is a national tragedy.”