I first met Daniel Kahneman about 25 years ago. I’d applied to graduate school in neuroscience at Princeton University, where he was on the faculty, and I was sitting in his office for an interview. Kahneman, who died today at the age of 90, must not have thought too highly of the occasion. “Conducting an interview is likely to diminish the accuracy of a selection procedure,” he’d later note in his best-selling book, Thinking, Fast and Slow. That had been the first finding in his long career as a psychologist: As a young recruit in the Israel Defense Forces, he’d assessed and overhauled the pointless 15-to-20-minute chats that were being used for sorting soldiers into different units. And yet there he and I were, sitting down for a 15-to-20-minute chat of our own.
I remember he was sweet, smart, and very strange. I knew him as a founder of behavioral economics, and I had a bare familiarity with the work on cognitive biases and judgment heuristics for which he was soon to win a Nobel Prize. I did not know that he’d lately switched the focus of his research to the science of well-being and how to measure it objectively. When I said during the interview that I’d been working in a brain-imaging lab, he began to talk about a plan he had to measure people’s level of delight directly from their brain. If neural happiness could be assessed, he said, then it could be maximized. I had little expertise—I’d only been a lab assistant—but the notion seemed far-fetched: You can’t just sum up a person’s happiness by counting voxels on a brain scan. I was chatting with a genius, yet somehow on this point he seemed … misguided?
I still believe that he was wrong, on this and many other things. He believed so too. Daniel Kahneman was the world’s greatest scholar of how people get things wrong. And he was a great observer of his own mistakes. He declared his wrongness many times, on matters large and small, in public and in private. He was wrong, he said, about the work that had won the Nobel Prize. He wallowed in the state of having been mistaken; it became a topic for his lectures, a pedagogical ideal. Science has its vaunted self-corrective impulse, but even so, few working scientists—and fewer still of those who gain significant renown—will ever really cop to their mistakes. Kahneman never stopped admitting fault. He did it almost to a fault.
Whether this instinct to self-debunk was a product of his intellectual humility, the politesse one learns from growing up in Paris, or some compulsion born of melancholia, I’m not qualified to say. What, exactly, was going on inside his brilliant mind is a matter for his friends, family, and biographers. Seen from the outside, though, his habit of reversal was an extraordinary gift. Kahneman’s careful, doubting mode of doing science was heroic. He got everything wrong, and yet somehow he was always right.
In 2011, he compiled his life’s work to that point into Thinking, Fast and Slow. Truly, the book is as strange as he was. While it might be found in airport bookstores next to business how-to and science-based self-help guides, its genre is unique. Across its 400-plus pages Kahneman lays out an extravagant taxonomy of human biases, fallacies, heuristics, and neglects, in the hope of making us aware of our mistakes, so that we might call out the mistakes that other people make. That’s all we can aspire to, he repeatedly reminds us, because mere recognition of an error doesn’t typically make it go away. “We would all like to have a warning bell that rings loudly whenever we are about to make a serious error, but no such bell is available, and cognitive illusions are generally more difficult to recognize than perceptual illusions,” he writes in the book’s conclusion. “The voice of reason may be much fainter than the loud and clear voice of an erroneous intuition.” That’s the struggle: We may not hear that voice, but we must attempt to listen.
Kahneman lived with one ear cocked; he made errors just the same. The book itself was a terrific struggle, as he said in interviews. He was miserable while writing it, and so plagued by doubts that he paid some colleagues to review the manuscript and then tell him, anonymously, whether he should throw it in the garbage to preserve his reputation. They said otherwise, and others deemed the finished book a masterpiece. Yet the timing of its publication turned out to be unfortunate. In its pages, Kahneman marveled at great length over the findings of a subfield of psychology known as social priming. But that work—not his own—quickly fell into disrepute, and a larger crisis over irreproducible results began to spread. Many of the studies that Kahneman had touted in his book—he called one an “instant classic” and said of others, “Disbelief is not an option”—turned out to be unsound. Their sample sizes were far too small, and their statistics could not be trusted. To say the book was riddled with scientific errors would not be entirely unfair.
If anyone should have caught those errors, it was Kahneman. Forty years earlier, in the very first paper he wrote with his close friend and colleague Amos Tversky, he had shown that even trained psychologists—even people like himself—are subject to a “consistent misperception of the world” that leads them to make poor judgments about sample sizes, and to draw the wrong conclusions from their data. In that sense, Kahneman had personally discovered and named the very cognitive bias that would eventually corrupt the academic literature he cited in his book.
In 2012, as the extent of that corruption became apparent, Kahneman intervened. While some of those whose work was now in question grew defensive, he put out an open letter calling for more scrutiny. In private email chains, he reportedly goaded colleagues to engage with critics and to participate in rigorous efforts to replicate their work. In the end, Kahneman admitted in a public forum that he’d been far too trusting of some suspect data. “I knew all I needed to know to moderate my enthusiasm for the surprising and elegant findings that I cited, but I did not think it through,” he wrote. He acknowledged the “special irony” of his mistake.
Kahneman once said that being wrong feels good, that it gives the pleasure of a sense of motion: “I used to think something and now I think something else.” He was always wrong, always learning, always going somewhere new. In the 2010s, he abandoned the work on happiness that we’d discussed during my grad-school interview, because he realized—to his surprise—that no one really wanted to be happy in the first place. People are more interested in being satisfied, which is something different. “I was very interested in maximizing experience, but this doesn’t seem to be what people want to do,” he told Tyler Cowen in an interview in 2018. “Happiness feels good in the moment. But it’s in the moment. What you’re left with are your memories. And that’s a very striking thing—that memories stay with you, and the reality of life is gone in an instant.”
The memories remain.
