**"What If? The Power of Counterfactuals"** - The Undoing Project: A Friendship That Changed Our Minds

Okay, so, like, um, this chapter, it's all about this weird thing called counterfactual thinking, right? And it's kind of a mystery.

So, there's this guy, Myers Shorr, and, uh, back in the, like, late '70s, he becomes the head of this mental health center, which is basically a teaching place for Harvard. And right away, he's gotta make this big decision, whether or not to promote this researcher, Alan Hobson.

Now, normally, this wouldn't be a big deal, but, you know, Hobson, he's been, like, totally slamming Freud's idea that dreams are all about our unconscious desires. He's saying, like, no, dreams actually come from, like, a certain part of the brain, and they don't really have anything to do with what we want. He's got proof that, like, when you dream and how long you dream, it's all, like, predictable. So, basically, dreams aren't about your mental state, they're just, like, your nervous system doing its thing. And, on top of that, Hobson's research is basically saying that it's, like, a total waste of money to have these analysts try to figure out your unconscious desires by interpreting your dreams.

So, Hobson's, like, changing the way people think about sleep and the brain. But here's the thing that's giving Shorr a headache: all of Hobson's big research on dreams, it was all done with his partner, Robert McCarley. And Shorr's like, "Ugh, group work, you know?" It's harder to get promoted when it's teamwork, 'cause the system is all about individual achievement. Like, they’re usually looking for, like, “What has *this* person done?”

Shorr, he really wants to push Hobson through, but he's gotta convince this committee, and they're, like, super picky. Shorr even says they didn't wanna promote anyone. So, when Shorr's trying to make his case for Hobson, the committee members are all, "Okay, but, like, what exactly did *Hobson* do in this partnership with McCarley? Break it down for us. What did each of them do?"

So, Shorr goes to Hobson and McCarley and he's like, "Okay, guys, what were your individual contributions?" And they're all, "Our individual contributions? Uh, who knows? We did everything together." And Shorr keeps pressing them, but, like, they seriously can't tell him who came up with which idea. So, Shorr's like, "Wow, that's... something."

And Shorr figures this has gotta be a bigger thing, so he starts looking for other people like them – people who've worked together for, like, at least five years and had, like, a really good partnership. He finds a comedy duo, a pair of piano players – one of them started playing with a partner 'cause they had stage fright – a couple of women who wrote mystery novels under the name "Emma Larson," and, uh, these famous British nutrition guys, McCance and Widdowson. They were so close, they, like, didn't even bother using their first names on their books, just their last names. Shorr remembers them being, like, totally against the idea that brown bread was healthier than white bread. Apparently, they, like, debunked that way back in 1934, but people still believed it.

And Shorr said almost everyone he talked to thought their partnership was, like, this crazy, special thing, so they were down to chat with him. The only exceptions were a couple of "stingy physicists" and those ice dancers, Torvill and Dean, who weren't really taking the interview seriously. Among the people who *did* wanna talk to Shorr were Amos Tversky and Daniel Kahneman.

Shorr found them in 1983 at a psychology conference in Anaheim, California. Daniel was 49, Amos was 46. They talked to Shorr together for, like, hours, and then they talked to him separately for hours. They talked about how excited they were when they first met and how they'd worked together over the years. Amos even said that when they met, they were able to answer questions that nobody else was asking, and they could talk about psychology without all the jargon and explain things around them. Shorr also asked them if they considered their work to be part of this new field of artificial intelligence, and Amos was all, "Nah, we don't study artificial intelligence, we study human stupidity."

Shorr thought Daniel and Amos had a lot in common with the other successful partners he'd talked to. Like, they were really good at creating this, like, exclusive club just for the two of them. Shorr said they really admired each other, but it wasn't just, like, blind admiration, you know? They usually didn't feel that way about other people, especially editors. And, just like those other partnerships, their close relationship made things tough with other people. Daniel even admitted that their partnership had caused some problems in his marriage. They also couldn't really say who contributed what to their work. Daniel was like, "You know, who did what? We didn't know, we weren't sure. And that was kind of beautiful, actually." Shorr could tell that Amos and Daniel knew, or at least, like, seemed to know, how much they needed each other. Daniel said that some geniuses can do it all on their own, but he and Amos weren't geniuses, but together, they were, like, unstoppable.

Unlike the other 19 pairs Shorr interviewed, Amos and Daniel weren't afraid to talk about the problems in their relationship. Shorr said that most people would avoid talking about conflict, and some flat-out wouldn't admit they had any. But not Amos and Daniel – or at least, not Daniel. He said that things got tough after he got married and after they moved to America. Amos was a little more private about it, but Shorr's notes from all their conversations showed that things had been shaky between them since they left Israel six years earlier. Daniel even complained about how everyone thought he was just agreeing with Amos, but that wasn't the case. He was saying it more to Amos than to Shorr. Daniel also said that the partnership had cost him something. He admitted that some of the work was clearly Amos's, like formal analysis, which was his strength and really important to their research. Daniel felt like his contributions weren't as obvious. Amos chimed in, but only a little. He thought that the unequal credit was just part of working together. Amos said that trying to figure out who deserves more credit is, like, a waste of energy and doesn't help the partnership. There's always gonna be someone who seems stronger. He called it, like, a law of equilibrium. Partnership is never, like, perfectly balanced. It's always shifting 'cause people don't like relationships that stay the same.

When he was alone with Shorr, Daniel would get even deeper. He hinted that he didn't think the problems were just coming from outside. He said that the rewards of academic success – like the ones they had – usually end up going to one person, or at least mostly to one person, and that's just how partnerships are. Amos couldn't really change that, and Daniel wasn't even sure if he wanted to. Then he just straight-up talked about how he felt about Amos. He thought Amos probably got most of the credit for their work. Daniel said he was always in Amos's shadow, and that made him tense. He was jealous, and he didn't like feeling that way. He told Shorr he was probably saying too much.

Shorr's impression was that Amos and Daniel had been through a rough patch, but the worst was over. They were able to talk about their problems openly, which Shorr thought was a good sign. They didn't really argue during the interviews. Their attitude toward conflict was totally different from the other people he interviewed. Shorr even said they were still playing Israeli card games together. Amos, especially, seemed optimistic. He thought they could keep working together like they always had. The American Psychological Association gave them both an award for their scientific contributions, which helped ease the tension a bit. Daniel confessed to Shorr that he'd been worried Amos would get the award on his own, and that would've been a disaster because he wouldn't have been able to handle it. The award, like, took away the pain, or at least that's how Shorr saw it.

Anyway, Shorr never ended up writing that book about great partnerships. Years later, he sent the interview tapes to Daniel. Daniel said that he listened to them from beginning to end, and it was clear that their relationship had already ended back then.

So, in late 1977, after Daniel said he wasn't coming back to Israel, everyone started saying that Amos was gonna leave too. Usually, colleges don't go around trying to recruit professors, and if they do, it takes forever. But this time, they were all, like, ready to go. They were like a couch potato who jumps up when the house is on fire. Harvard offered Amos a full professorship right away, but it took them a few weeks to offer Barbara, his wife, a teaching assistant position. The University of Michigan, being a big school, quickly put together, like, four full professorships, for Daniel, his wife Anne, Barbara, and Amos. The University of California, Berkeley, which had turned Daniel down because he was too old, was now trying to get Amos. But no one moved as fast as Stanford.

The guy in charge of the recruiting at Stanford was this young star in the psychology department, Lee Ross. He knew that the big public universities would take Barbara and Daniel and Anne just to keep Amos. Stanford wasn't big enough to offer four jobs right away. Ross said they came up with two things that the other schools couldn't do: make an offer really fast and finalize it quickly. They wanted to convince Amos to choose Stanford, and the best way to do that was to show him how efficient they were.

Ross thought that what happened next was, like, totally unheard of in the history of American universities. As soon as he heard Amos was considering offers, he got the whole Stanford psychology department together. Ross said he should have let Amos see what was happening. He told them a classic Yiddish story about a bachelor who's happy on his own. One day, a matchmaker comes to him and says, "Wanna let me find you someone to marry?" The bachelor asks what she's like. The matchmaker says she's special, beautiful like Sophia Loren, but younger, and rich, like an heir to the Rothschild fortune. The bachelor says, "Then she must be an idiot." The matchmaker says she's been nominated for the Nobel Prize in physics and chemistry. The bachelor says, "I'll take her!" The matchmaker replies, "Great, we're halfway there!" Ross then said that everyone there would say "I'll take him!" after he introduced them to Amos, but he'd have to tell them they were only halfway there.

Ross wasn't sure if he needed to be so over-the-top, though. He said that everyone who was involved in this was, like, patting themselves on the back for their judgment, but it wasn't a big deal. The same day, the whole Stanford psychology department went to the school president and said they didn't have any documents or recommendations, but they should trust them. That afternoon, Stanford decided to offer Amos a full professorship.

Amos later said that he would've regretted choosing either Harvard or Stanford. If he'd gone to Harvard, he would've missed the good weather and lifestyle in Palo Alto. And at Stanford, he would've regretted not being a Harvard professor, even if it was just for a second. He never said anything about Amos and Daniel needing to be together, though. Stanford wasn't totally uninterested in Daniel. Ross said that there was a really practical question, you know: "Do you hire two professors who do the same research?" Hiring just Amos would let them benefit from their partnership, and that was, like, a cold reality. Daniel wanted all four of them to go to Michigan, but Amos only wanted to go to Harvard or Stanford. Since Harvard and Stanford didn't invite him, and Berkeley said they didn't wanna hire him, Daniel and Anne ended up at the University of British Columbia in Vancouver. He and Amos agreed to fly to each other's cities every other week.

Back then, Daniel was still feeling pretty confident. He said that the prospect theory had made them feel, like, they could do anything. They hadn't started to drift apart yet. After Stanford offered Amos the job faster than anyone else, Amos gave a normal talk in front of Daniel, and he even talked about prospect theory. Daniel said that all he felt was pride, which surprised him, because he thought his gut reaction should have been jealousy. When Daniel left Palo Alto for Vancouver in 1978, he realized more than ever that fate was a weird thing. His kids were far away, and so were his former colleagues, his lab, and the country he thought he'd never leave. His soul was still in Israel. He said that when he thought about all that, his life was never the same. He said he changed his life. He was always thinking about what could have been.

In that strange state of mind, he kept thinking about his nephew, Ilan. Ilan was a navigator on an Israeli Air Force fighter jet, and he was 21 during the Yom Kippur War. After the war, he got Daniel to listen to a recording he'd made on the plane when he was in the back and saw an Egyptian MiG fighter plane coming at them from behind. On the tape, Ilan's voice shouts to the pilot to go down, that the other plane was coming after them. When he listened to the tape, Daniel could hear the young man trembling. He wanted his uncle to hear what he'd gone through. Ilan was lucky to survive the war, but a year and a half later, in March 1975, five days before he was supposed to leave the military, he died in an accident. The pilot he was with was blinded by a bright light during a flight, and the plane crashed nose-first into the ground.

They thought they were going up, but they were actually going down. It's a common mistake. Pilots often lose their sense of direction. When a weightless plane is spinning toward the ground at 600 miles per hour, the human hearing system can't work right, and the human brain can't calculate complex probabilities. Pilots can easily get confused, which is why pilots without instrument ratings usually only survive for 178 seconds.

After Ilan died, his family and friends were really sad. They kept saying "what if." What if Ilan had left the Air Force a week before the accident? What if he'd taken over when the pilot was blinded? Everyone was thinking about what could have been, a world where the tragedy never happened. Daniel noticed that this thinking wasn't random. People weren't just making up anything. If Ilan had had another year left in the Air Force, no one would have said "What if he'd left a year earlier?" And no one would have said "What if the pilot had a cold that day?" or "What if the plane had been grounded because of mechanical problems?" And definitely no one would have said "What if Israel didn't have an Air Force?" Ilan could have survived in all those scenarios, but his family wouldn't have thought about them.

Of course, there were thousands of other possibilities, but people seemed to only think about a few. When they were trying to undo the tragedy in their minds, they were following certain rules. Daniel was following the same rules when he was thinking about his own life.

Shortly after arriving in Vancouver, Daniel had Amos send him all their old notes about regret. They had spent a whole year in Jerusalem talking about the idea, including how people expect to feel bad and whether that affects their choices. Now, Daniel wanted to look at regret and other emotions in a new way. He wanted to know how people deal with things that have already happened. He hoped this research would add something new to his and Amos's work on judgment and decision-making. They wrote in their notes that emotions like hope in despair, relief, or regret could be part of decision theory because they're important emotions people have when they face certain outcomes. However, people are biased about these emotions. They think that mature people should feel the right emotion for the situation and shouldn't look for comfort or balance in unrealistic fantasies.

So, Daniel came up with a fourth heuristic, which he later called "simulation," on top of availability, representativeness, and anchoring. It was about how impossible possibilities affect human thought. In life, people often imagine the future. What if I speak my mind instead of pretending to agree? What if they kick the ball toward me and it lands at my feet? What if I say no to his offer? These imagined scenarios often become part of how people make judgments and decisions. However, not all scenarios are easy to imagine. Some are blocked from our minds, like the regrets people feel when they face tragedy. They're all limited by certain rules. By figuring out these rules and understanding how the brain tries to undo things that have happened, you can understand how people think ahead before things happen.

So, Daniel, all alone in Vancouver, became obsessed with this new idea: what separates the real world from the imagined world? In the research he and Amos had already done, they mostly looked for patterns in problems that no one had ever studied before. Now, they had the same problem again. Daniel wanted to know how people imagine possibilities that are different from what really happened when they're thinking about counterfactuals. Basically, he wanted to understand the rules of imagination.

In one of the scenarios Daniel created for his experiments, a new and easily angered coworker named Richard Teas became one of the main characters.

Mr. Crane and Mr. Teas were supposed to fly on two different flights that were supposed to take off at the same time. They took the same bus from the city to the airport, but they got stuck in traffic. When they got to the airport, they were 30 minutes late for their flights.

Mr. Crane found out that his flight had left on time half an hour earlier.

Mr. Teas found out that his flight was delayed and had left five minutes earlier.

Who feels worse?

They were both in the same situation. They both expected to miss their flights, and they both didn't make it in time. However, 96% of the people who were asked thought that Mr. Teas felt worse. It seems like everyone agrees that the reality of a situation isn't the only thing that causes frustration. How close that reality is to another reality also affects people's emotions. In the example, how close Mr. Teas was to catching his flight is the important part. Daniel wrote in a lecture note that Mr. Teas feels more frustrated because he was more likely to catch his flight. Similar examples have this, like, *Alice in Wonderland* vibe, where imagination and reality are mixed together for no reason. Why can't Mr. Crane imagine getting there half an hour early to catch his flight? Clearly, people's imaginations are limited.

And Daniel was trying to study those limits. He wanted to look deeper into what he called "counterfactual emotions," or the emotions that make people imagine a fake reality to ease the pain of the real situation. The best example of a counterfactual emotion is regret, and its main features also apply to frustration and jealousy. In a letter to Amos, Daniel called them "unattainable emotions." These emotions can be described with simple math. Daniel thought that the strength of the emotions was controlled by two things: how much people want another reality and how likely that other reality is to happen. A lot of the time, things that people regret or feel bad about aren't easy to undo. When people feel frustrated, they need to undo something in the environment. When they feel regret, they need to undo something they did. Daniel wrote that undoing frustration or regret follows basically the same rules. People need to go through a more or less reasonable path to get to the imagined world.

Jealousy is different. People don't need to build an imagined situation to feel jealous. It seems like the ability to imagine different situations depends on how similar you are to the person you're jealous of. To feel jealous, you just need to put yourself in their shoes. You don't need to imagine a reasonable scenario. It's strange, but jealousy doesn't need imagination.

Daniel, all alone in a different place, was stuck with these weird ideas for months. In early 1979, he sent Amos some notes called "Undoing the World." He wrote that he'd been thinking about how people deal with disasters and had come up with different ways to undo the pain they cause. He hoped to figure out how people think when they face disastrous results.

A shop owner is robbed at night. He fights back, but the robber hits him on the head, and he loses consciousness. He's found dead.

Two cars crash head-on because both drivers try to pass in bad conditions.

A man has a heart attack. He tries to call for help, but he can't reach the phone and dies.

Someone is shot and killed in a hunting accident.

He wrote that you would look at these tragedies. How would you look at Kennedy's assassination? The start of World War II? He wrote eight or nine pages. Imagination isn't a bird that can fly freely. It's just a tool that takes meaning from the world by removing all its endless possibilities. Imagination follows a set of rules: the rules of undoing. One of them is that the more you remove from the current situation to imagine another reality, the harder it is to undo. Between someone dying in an earthquake and someone dying from a lightning strike, people seem more likely to think about the latter because to undo an earthquake, you'd have to consider all the earthquakes that have ever happened. Daniel wrote that the more consequences an event has, the harder it is to undo it. Another related rule is that the event becomes less difficult to accept when you move it further back in time. Over time, the consequences of any event build up, leading to more things that need to be undone. The more there is to undo, the less likely the mind is to try to undo it. Maybe that's how time heals wounds.

Daniel's "focus principle" was even more common. He wrote that people often imagine a main character for a scenario, and that they imagine the scenario as constant, with only the main character moving. It's impossible to imagine a bullet fired by Oswald being blown away by the wind in Kennedy's assassination. However, that rule doesn't apply when the person doing the undoing is the main character because it's harder for a person to undo their own actions. Daniel wrote that it's harder to change or replace yourself than it is to change or replace others. The new world you imagine has to be very different from the world you're in. He might have some freedom to imagine things, but he can't just become someone else.

People are most likely to think about counterfactuals after unexpected events. A middle-aged banker drives the same route to work every day. One day, he chooses a different route, and a kid skipping school runs a red light in a convertible truck, hits his car, and kills him. When people are asked about this event, they think about the route the banker chose that day. If he'd taken his normal route, none of it would have happened! But if he'd taken his normal route and still died because a kid skipping school ran a red light, no one would have thought about him not taking that route. People seem to feel very different about the results of normal situations and the results of abnormal situations.

When trying to undo unexpected events, the mind often ignores probability. The best way to save the banker would have been to change the timing of the event. If he or the kid skipping school had been a few seconds earlier or later, the cars wouldn't have crashed. But people don't think about it that way when they're undoing the tragedy. It's much easier for them to undo the unusual part of the event. Daniel wrote that you might want to have some fun and imagine Hitler. He then mentioned that Hitler had achieved his first dream and become a painter in Vienna. He then asked Amos to imagine the opposite, which he called counterfactual. He reminded Amos that when the egg was fertilized, Adolf Hitler could have been a baby girl. The possibility of him becoming an artist might not be higher than the possibility of him being born a woman. So, why do we think that the former is acceptable when we're imagining counterfactuals about Hitler, but the latter is illogical?

Daniel thought that this mechanism of imagination reminded him of his cross-country skiing experience. He'd taken two basic courses and found that skiing uphill was much harder than skiing downhill. When faced with that situation, people would rather ski downhill. Daniel called that the "downhill rule."

While he was thinking about these new ideas, he had an unprecedented feeling of being able to move quickly without Amos. At the end of the letter, he wrote that he hoped to hear back before they met the following Sunday, because Amos's opinion was important to him. Daniel didn't say whether Amos replied to him, but he probably didn't. Amos seemed interested in Daniel's new ideas, but he somehow didn't get involved. Daniel said that he hardly said anything, which had never happened before. He thought Amos might be feeling down, which wasn't like him. After leaving Israel, Amos had privately told close friends that he didn't feel guilty about leaving his country. But he also hadn't expected to miss his homeland so much. Maybe that was the problem, and Amos wasn't the same after formally immigrating to America. Or maybe Daniel's new ideas were too different from their previous research. Up until then, their research had always started by challenging a widely accepted theory. They would find the flaws in those theories and then create a new, more convincing theory of behavior. But there wasn't an existing theory of human imagination for them to pick apart or completely overturn.

Another problem was that the difference in their positions had created a gap between them. When Amos visited the University of British Columbia, it seemed like he was slumming it. Daniel went up to Palo Alto, Amos came down to Vancouver. Daniel said that Amos had always been critical, and he could tell that he thought the place was rough. One night, they were chatting, and Amos complimented Stanford, saying that everyone there made him feel outstanding. Daniel remembered that being a trigger. He knew Amos didn't mean to, and he probably regretted saying it, but he remembered feeling like he was condescending and pitying him, which he couldn't stand.

But Daniel's main feeling was frustration. For years, almost every new idea he had was born with Amos's help. They had never done anything alone, and they had never worked with anyone else. That was the miracle: accepting each other's ideas without holding back and then turning their thoughts into one. Daniel later told Myers Shorr that it felt like he came up with the ideas most of the time, but the final results were far beyond what he had expected. Now, he was back to fighting alone, and the ideas that would have helped him go further, Amos's ideas, were gone. Daniel said that he had countless ideas, but Amos wasn't there anymore, and the ideas were useless because only Amos could bring them to life.

Months after Daniel sent Amos the letter, they went to the University of Michigan to give two lectures at the Katz-Newcomb Conference, which was famous in their field. Daniel was a little surprised that the organizers had invited both of them, instead of just Amos. Amos's lecture was about their joint research on framing effects, which confirmed Daniel's suspicion that Amos wasn't interested in his new ideas. Daniel would be talking about the new ideas he'd come up with on his own in the nine months since they'd separated, which he called "Psychology in Imaginary Space." He explained that since everyone there was their like-minded colleagues, he and Amos thought it might be good to discuss his preliminary research on the role of unrealized possibilities in the emotional realm and how we interpret those possibilities.

He then explained the rules of counterfactual thinking. Besides the banker who died on his way to work in a collision with a kid skipping school, he also created more simulated scenarios. For example, there was an unlucky guy who had a heart attack while driving and died before he could hit the brakes. Most of the scenarios were things he'd made up in the middle of the night in Vancouver. The ideas often came to him unexpectedly, so he kept a notebook next to his bed. If Amos had a more perceptive mind, Daniel had a better ability to tell stories. After they'd started their new lives in North America, Amos might have been in the lead, but that wouldn't last forever, and everyone would see what Daniel could do. He could tell that everyone was hooked on his lecture. No one rushed to leave when it was over. People gathered to chat. Amos's advisor, Clyde Coombs, came up to them, looking impressed. He asked where all those ideas had come from. Amos replied that Daniel and he hadn't talked about them.

Daniel and he hadn't talked about them.

That sentence cast a shadow on Daniel's heart. He admitted later that their relationship had basically ended from that moment on. He had imagined many possibilities to keep that from happening. But he hadn't thought about Clyde Coombs not asking the question, or he and Amos being as laid-back as each other, or him not leaving Israel. He thought about Amos being more humble. In his eyes, Amos was the main character in the event, the center of attention. He had refused the opportunity to praise Daniel when it was offered to him. Everything was still going on, but that scene stayed with Daniel for a long time. Daniel said that couples in love also have disagreements. You realize something's wrong, that things aren't good, but the relationship is still going on. You love the other person, but you can feel a force pushing you away, and you think maybe things will change. You're hoping that something will happen to strengthen and repair the relationship. But this time, nothing happened. Daniel said that he wished Amos would have reflected on what had happened, but he didn't do that and didn't think he needed to.

After the trip to Michigan, Daniel never mentioned Amos's name again when talking about his counterfactual thinking research. That was unheard of for him. For 10 years, they had strictly followed an agreement to never share information with others who had similar research interests. In late 1979 or early 1980, Daniel started talking to a young teaching assistant at the University of British Columbia named Dale Miller and exchanging ideas with him about the difference between reality and imagination. When Miller asked about Amos, Daniel said that they had stopped working together. Miller said that he hadn't gotten over the shadow that Amos had cast, and he could tell that he cared a lot about it. Soon after, Daniel and Miller started working on the "Undoing the World" article together. Miller said that he thought they had agreed to work with others separately, but he insisted that his days of working with Amos were completely over. He remembered many conversations with Daniel, who seemed worried and sometimes reminded him not to be too harsh on him, because it was the first time he'd worked with someone since Amos.

If Amos didn't care as much about the lecture at Katz-Newcomb as Daniel did, it was because opportunities like that were common for him. More than one of the graduate students at Stanford remembered their advisor as a stand-up comedian who was busy running around the world to perform at nightclubs. His wife, Barbara, remembered that he liked to think while he talked. She said that you could hear him talking to himself through the door when he was showering. The kids were used to their father talking to himself. His son, Tal, said that he looked like a mentally ill patient when he was talking to himself. Sometimes, they would see their dad driving home in his brown Honda, stopping on the street in front of the house, and starting to talk to himself again. His daughter, Donna, said that he would putter along at three miles per hour or suddenly speed up, which meant he'd just figured something out.

A few weeks before the Katz-Newcomb lectures, in early April 1979, Amos was busy dealing with the Soviet Union. He joined a delegation of 10 Western psychologists on a special mission. At the time, Soviet psychologists were trying to convince the government to recognize mathematical psychology as legitimate by the Academy of Sciences. To do that, they asked their American colleagues for support. Two well-known mathematical psychologists, William Estes and Duncan Luce, volunteered and invited some of the top psychologists in America, most of whom were older, senior scholars. Amos was one of the few young people, along with his colleague at Stanford, Brian Wandell. Wandell remembered that the old guys thought that they could help the Soviets save face for psychology by facing up to Marxism, which meant that psychology had no reason to exist.

They spent a lot of time trying to figure out why psychology had that image in Marxism. The Soviet psychologists were like con artists. Wandell said that they thought the Soviets would have a few psychologists doing scientific research, but they didn't. As the Soviets and Americans took turns giving presentations, the Americans would give detailed descriptions of decision theory, while the Soviets would share weird ideas. One guy talked about how drinking beer interfered with the brain waves of drinking vodka. Wandell said that they would think of a question and write it up as a paper, while the Soviets would just brag about it, and they would be impressed. Some of them studied the meaning of life and thought you could calculate it with a formula with variable E.

The Soviets didn't know anything about decision theory and didn't seem very interested in it. But there were exceptions. Wandell said that one guy gave a fairly insightful argument, at least compared to his colleagues. It turned out that he was a KGB agent, and his arguments were just what he had been trained in psychology. Wandell said that they found out who he really was when they learned that he had also attended a physics conference and given the same talk. He was the only guy that Amos liked.

They stayed in hotels where the toilets didn't flush and the heaters didn't heat. The rooms were bugged, and plainclothes agents followed them everywhere. Wandell said that everyone was a little shaken up for the first few days, and they had nowhere to hide. Amos thought the whole thing was ridiculous. Wandell said that they paid extra attention to Amos, probably because he was Israeli. He walked around Red Square in his special way and gave Wandell a look that said, "Come on, let's lose them!" And he actually lost the agents who were following him. When they finally caught him, he'd hidden in a department store, and the Soviets were furious. Wandell said that they chewed them out.

In that cold, bugged room, Amos spent some time editing and adding to an article he called "Undoing the World," which eventually grew to about 40 pages. The dense notes sounded like a diamond cutting machine. Clearly, Amos wanted to turn Daniel's ideas into a complete theory. But Daniel didn't know that Amos was also racking his brain to imagine his virtual scenarios:

David P. died in a plane crash. Which of the following counterfactuals is easier to think about?

-If the plane hadn't crashed.

-If David P. had taken a different plane.

Amos didn't reply to Daniel's long letter. Instead, he took notes to make sense of all the ideas that Daniel had poured onto the paper. He wrote that the real world is often unexpected and doesn't make as much sense as the world we imagine. He said that we can sort those imaginations based on two principles: first, reasonableness, and second, similarity to reality. He wrote eight pages of notes over the next few days, hoping to create a logical and defensible theory of imagination. Barbara said that the ideas fascinated him, the same way that decision theory had. She said that it was also a decision, but that people hadn't chosen to do it. He thought a lot about the title, because he wanted the title to make his focus clear. First, he came up with the term "deletion heuristic," then he named the new theory "possibility theory," then he changed it to "scenario theory," then "imaginary space theory." Finally, he chose the name "shadow theory." Amos wrote in his notes that according to shadow theory, alternate situations or possible scenarios determine our expectations of reality, how we see reality, how we look back on reality, how we explain reality, and what kind of emotional state we fall into because of it. Near the end of his notes, he summed it all up with one sentence: what is reality? Reality is a cloud full of all kinds of possibilities.

Amos wasn't uninterested in Daniel's new ideas, like Daniel thought. The main reason was that they couldn't just shut themselves in a room and talk about it like they used to. Conversations that should have been face-to-face became like two people talking over each other. The result of that unprecedented distance was that they were more clear than ever about who had come up with which idea. Amos mentioned it to Myers Shorr, a bit critically, saying that they knew whose idea it was because they weren't together and everything was written in letters. He said that they used to call each other as soon as a new idea popped up, but now, you think of something, and you put