The Undoing Project: A Friendship that Changed the World(28)

Edwards wasn’t setting himself, or his field, in opposition to economics. He was merely proposing that psychologists be invited, or perhaps invite themselves, to test both the assumptions and the predictions made by economists. Economists assumed that people were “rational.” What did they mean by that? At the very least, they meant that people could figure out what they wanted. Given some array of choices, they could order them logically, according to their tastes. For example, if they were handed a menu that listed three hot drinks, and they said that at some given moment they preferred coffee to tea, and tea to hot chocolate, they should logically prefer coffee to hot chocolate. If they preferred A to B and B to C, they should prefer A to C. In the academic jargon, they were “transitive.” If people couldn’t order their preferences logically, how would any market ever function properly? If people preferred coffee to tea and tea to hot chocolate—but then turned around and chose hot chocolate over coffee—they’d never finish choosing. They’d be willing, in principle, to pay to switch from hot chocolate to tea and also to switch from tea to coffee—and then pay again to switch from coffee to hot chocolate. They’d never settle on a drink but instead would be stuck in this mad infinite loop in which they kept paying to upgrade from the drink they had to a drink they liked better.

Here was one of the predictions that economists made that Edwards thought psychologists might test: Are actual human beings transitive? If at any given moment they preferred coffee to tea and tea to hot chocolate, did they prefer coffee to hot chocolate? A few people had recently looked into the matter, Edwards noted, among them a mathematician named Kenneth May. Writing in a leading economics journal, Econometrica, May described how he had tested just how logical his own students were when asked to choose a spouse. He’d presented students with three potential mates, ranked by three qualities: how good-looking they were, how smart they were, and how much money they had. None of the three potential mates was extreme in any one way: No one was so poor, dumb, or hard on the eye as to be repugnant. Each had relative strengths and weaknesses: Each ranked highest in one category, second highest in another, and last in the third. May’s students, in making their choices, never faced all three potential marriage partners at the same time. Instead they were shown pairs, and asked to choose between them. For example, they might be asked to choose between the potential mate who was the brightest, second-best-looking, but poorest, and the potential mate who was the richest, the second-brightest, but the least good-looking.

Once the dust had settled in this flurry of decision making, more than a quarter of the students had revealed themselves as irrational, at least from the point of view of economic theory. They’d decided that they would rather marry Jim than Bill, and Bill than Harry—but then also said that they would rather marry Harry than Jim. If people could buy and sell spouses like hot drinks, some large number of them would never settle on one spouse but would instead keep paying to upgrade. Why? May didn’t offer a full explanation, but he suggested the beginning of one: Because Jim and Bill and Harry each had relative strengths and weaknesses, they were hard to compare. “It is just these non-comparable cases that are of interest,” wrote May. “Comparison of alternatives in which one is superior to the other in every respect makes for a simple but rather trivial theory.”

Amnon showed Ward Edwards’s paper on decision making to Amos, and Amos grew very excited. “Amos will smell gold before anyone else will smell it,” said Amnon. “And he smelled gold.”



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In the fall of 1961, a few weeks after Amnon flew to the University of North Carolina, Amos left Jerusalem for the University of Michigan—where Ward Edwards had moved after being fired by Johns Hopkins, supposedly for not bothering to show up for the classes he was meant to be teaching. Neither Amnon nor Amos knew much about American universities. Amnon, who had just been assigned to North Carolina by a Fulbright scholarship committee, had to pull out his Atlas of the World to find it. Amos was able to read English, but he spoke so little that, when he told people where he planned to go, they assumed he was joking. “How will he even survive?” his friend Amia Lieblich asked herself. Neither Amnon nor Amos saw that they had any real choice. “There was nobody to teach us at Hebrew University,” Amnon said. “We had to leave.” Both Amnon and Amos assumed that the move was temporary: They would learn whatever there was to learn about this new field of decision making in the United States and then return to Israel and work together.

The earliest sightings of Amos Tversky in the United States are anomalies in the History of Amos. In their first week of classes, fellow students saw a silent, seemingly dutiful foreigner taking notes. They looked upon him with pity. “My first memory is of him being really, really quiet,” recalls fellow graduate student Paul Slovic. “Which is funny, because later on he really wasn’t quiet.” Seeing Amos writing from right to left, one student suggested that he might suffer from some mental disorder. (He was writing in Hebrew.) Stripped of the power of speech, Amos was jolted out of character. Long after the fact, Paul Slovic guessed that in his first few months away from home Amos merely had been biding his time. Until he knew exactly what he was saying, he wouldn’t say it.

By the middle of his first year Amos knew what he was saying—and from that moment the Amos stories came thick and fast. There was the time that Amos walked into an Ann Arbor diner and ordered a hamburger with relish. The waiter said they didn’t have relish. Okay, Amos said, I’ll have tomato. We don’t have tomato, either, said the waiter. “Can you tell me what else you don’t have?” asked Amos. There was the time Amos had arrived late for what everyone expected would be a grueling test, given by a dreaded professor of statistics, John Milholland. Amos slid into a desk just as the test was being passed out. The room was dead silent, the students anxious and tense. As Milholland reached his desk, Amos turned to the person seated next to him and said, “Forever and forever, farewell, John Milholland If we do meet again, why, we shall smile If not, why then, this parting was well made”: lines spoken by Brutus to Cassius in act 5, scene 1, of Julius Caesar. He aced the test.