The Undoing Project: A Friendship That Changed Our Minds

by Michael Lewis

The more easily people can call some scenario to mind—the more available it is to them—the more probable they find it to be.

The stories we make up, rooted in our memories, effectively replace probability judgments. “The production of a compelling scenario is likely to constrain future thinking,” wrote Danny and Amos. “There is much evidence showing that, once an uncertain situation has been perceived or interpreted in a particular fashion, it is quite difficult to view it in any other way.”

“Images of the future are shaped by experience of the past,” they wrote, turning on its head Santayana’s famous lines about the importance of history: Those who cannot remember the past are condemned to repeat it.

People often work hard to obtain information they already have And avoid new knowledge

Man is a deterministic device thrown into a probabilistic Universe

“When no specific evidence is given, the prior probabilities are properly utilized; when worthless specific evidence is given, prior probabilities are ignored.”*

No one saw what Danny saw: that the pilots would have tended to do better after an especially poor maneuver, or worse after an especially great one, if no one had said anything at all. Man’s inability to see the power of regression to the mean leaves him blind to the nature of the world around him.

Once we have adopted a particular hypothesis or interpretation, we grossly exaggerate the likelihood of that hypothesis, and find it very difficult to see things any other way.

Amos was polite about it. He did not say, as he often said, “It is amazing how dull history books are, given how much of what’s in them must be invented.”

Amos had a phrase for this. “Creeping determinism,” he called it—and jotted in his notes one of its many costs: “He who sees the past as surprise-free is bound to have a future full of surprises.”

One passage in particular stuck with him—it was in the section on this thing they called “availability.” It talked about the role of the imagination in human error. “The risk involved in an adventurous expedition, for example, is evaluated by imagining contingencies with which the expedition is not equipped to cope,” the authors wrote. “If many such difficulties are vividly portrayed, the expedition can be made to appear exceedingly dangerous, although the ease with which disasters are imagined need not reflect their actual likelihood. Conversely, the risk involved in an undertaking may be grossly underestimated if some possible dangers are either difficult to conceive of, or simply do not come to mind.”

A part of good science is to see what everyone else can see but think what no one else has ever said.

The difference between being very smart and very foolish is often very small.

The secret to doing good research is always to be a little underemployed. You waste years by not being able to waste hours.

It is sometimes easier to make the world a better place than to prove you have made the world a better place.

When they made decisions, people did not seek to maximize utility. They sought to minimize regret.

When choosing between sure things and gambles, people’s desire to avoid loss exceeded their desire to secure gain.

For most people, the happiness involved in receiving a desirable object is smaller than the unhappiness involved in losing the same object.”

People did not choose between things. They chose between descriptions of things.

Danny now had an idea that there might be a fourth heuristic—to add to availability, representativeness, and anchoring. “The simulation heuristic,” he’d eventually call it, and it was all about the power of unrealized possibilities to contaminate people’s minds. As they moved through the world, people ran simulations of the future. What if I say what I think instead of pretending to agree? What if they hit it to me and the grounder goes through my legs? What happens if I say no to his proposal instead of yes? They based their judgments and decisions in part on these imagined scenarios. And yet not all scenarios were equally easy to imagine; they were constrained, much in the way that people’s minds seemed constrained when they “undid” some tragedy. Discover the mental rules that the mind obeyed when it undid events after they had occurred and you might find, in the bargain, how it simulated reality before it occurred.

People seemed less likely to undo someone being killed by a massive earthquake than they were to undo a person’s being killed by a bolt of lightning, because undoing the earthquake required them to undo all the earthquake had done. “The more consequences an event has, the larger the change that is involved in eliminating that event,” Danny wrote to Amos.