Remembering Daniel Kahneman

Last week, Daniel Kahneman, professor emeritus of Psychology and Public Affairs at Princeton University, died at the age of 90. His pioneering work in psychology to advance what came to be called behavioral economics led to his receiving the Nobel Prize in Economics in 2002. This work influenced many scholars far and wide, particularly here at Columbia. Below, several members of the faculty pay tribute to Kahneman and the influence he and his longtime collaborator, the Stanford psychologist Amos Tversky, have had on their own research.

The Reframing of Loss

Daniel Kahneman—together with his friend, colleague, and collaborator Amos Tversky—created a new scientific discipline, one that would give us the tools to quantify those qualities of the human experience that seem unquantifiable: judgements, decisions, happiness, subjective feelings. For his contributions to understanding human decision-making, Kahneman was awarded the Nobel Prize in Economics in 2002.

Kahneman’s death is a loss for anyone interested in understanding human behavior or in using that understanding to make the world better. Danny, as I came to know him, did both. He had an outsize impact on my scientific thinking and on my idea of what it means to be a scientist in the world.

I first learned of the work of Kahneman and Tversky as a college student. In a research-methods class we were assigned a paper to read: “The Framing of Decisions and the Psychology of Choice.” The paper showed that people change their decisions based on how the options are described, whether they are framed in a positive context or a negative one. For example, they asked people to choose between treatments for a hypothetical deadly pandemic, offering choices that differ in whether they are presented with a certain likelihood of saving people versus a certain likelihood of people dying. Even when the statistics of the outcomes are identical, people are more likely to choose the treatment if it is framed as positive. “The psychological principles that govern the perception of decision problems and the evaluation of probabilities and outcomes produce predictable shifts of preference when the same problem is framed in different ways,” Tversky and Kahneman wrote in 1981.

Losses, too, can be reframed, depending on how we are led to think about them. 

I thought the idea was intriguing but I was skeptical. Sure, people were prone to irrational decisions. But was it really possible to use a rigorous scientific approach to probe the irrationality of human behavior? It was hard for me to believe that irrationality was systematic. The next year, for my honor’s thesis, I tried to replicate and extend the framing effect. My lab partner and I fully expected the experiment to fail. Instead, the data we collected showed a clear replication.

I went on to do a PhD in neuroscience, but the lesson stayed with me: It is possible to study complex aspects of human behavior with rigorous science. It is possible to precisely quantify subjective experience and to develop rigorous models of the messiness of human behavior. Kahneman and Tversky had shown us how.

In the years that followed, I was fortunate to get to know Danny better. He brought both grace and playfulness to science. He also brought the beauty and elegance of science to societal issues. When controversies brewed about a replication crisis in behavioral science, Danny weighed in. When controversies in Israel came up around judicial changes and their threat to democracy, Danny weighed in. He took the science seriously and brought it to bear on serious issues.

In one of our conversations, we spoke about loss. Not monetary loss and gains, a topic central to his scientific work, but about the subjective experience of loss and the role of memory. Loss and memory are on my mind again, as is the idea of reframing loss as gain.

With Daniel Kahneman's death, we lost a brilliant, curious and thoughtful person. But even now, especially now, I am thinking of all that we gained: a scientist who wasn’t afraid to ask difficult questions, to question and re-evaluate his stance, or to admit to making mistakes. A colleague who demanded that we use science to live better and do better, because we can, and because it matters. 

     -Daphna Shohamy, Kavli Professor of Brain Science, director and CEO of Columbia’s Zuckerman Mind Brain Behavior Institute, codirector of Columbia’s Kavli Institute for Brain Science

Kahneman and Tversky Made Us See

I started running experiments as a mainstream economist, testing predictions about strategic choices in group interactions. The goal was to identify or reject general laws, and the approach was very far from psychology: Focusing on differences in behavior across individuals, based on culture or gender or background, would go against the search for systematic forces.

Once I moved to the lab, however, it was impossible to ignore not only the deviations from standard theory, but also the compelling, intuitive nature of many of these deviations. Loss aversion, prospect theory, probability weighing, neglect of correlation, of base rates, of mean-reversion, these are all regularities of behavior that no experimentalist can be blind to. I became by necessity a reluctant behavioral economist. And yet, we needed Kahneman and Tversky to make us see. How did they succeed in keeping their minds so original and free? Their work has revolutionized how we approach and understand economic choices—Kahneman and Tversky did not change the discipline at the margin, they altered it radically.

One observation is important. Economists’ original fear of psychology came from the ambition to reach general principles, systematic regularities that are robust to personal idiosyncrasies. And that indeed is what Kahneman and Tversky gave us. Not occasional peculiarities of this or that individual, of this or that group, but consistent behavioral facts that approach the status of law. Research now aims at better understanding their origin; it does not question their existence and predictability.  As we mourn Daniel Kahneman’s death, we celebrate his contributions and his legacy. 

     -Alessandra Casella, professor of Economics and professor of Political Science

The Truth About Insight

A few months before publication of his book Thinking, Fast and Slow in 2011, the Center for Decision Sciences had scheduled Danny to present in our seminar series. We were excited because he had decided to present his first ‘book talk’ about his book with us. Expecting a healthy crowd, we scheduled the talk in Uris 301, the biggest classroom in Columbia Business School.

I arrived in the room a half hour early to find Danny, sitting alone in the large room, obsessing over his laptop. He confided that he had just changed two-thirds of the slides for the talk and was quite anxious and unsure about how to present the material. Of course, after the introduction, Danny presented in his usual charming, erudite style, communicating the distinction between System 1 and System 2 with clarity to an engaged audience. Afterwards, I asked him how he thought it went, and he said, “It was awful, but at least now I know how to make it better.” Needless to say, the book went on to become an international best seller.

This was not false modesty. Having studied over-confidence throughout his career, Danny seemed immune to its effects. This, while surely maddening to some co-authors, resulted in work that was more insightful and, most important to Danny and to us, correct. He was not always right, but always responsive to evidence, supportive or contradictory.  For example, when some of the evidence cited in the book was questioned as a result of the replication crisis in psychology, Danny revised his opinion, writing in the comments of a critical blog: “I placed too much faith in underpowered studies.”

The best tribute to Danny, I believe, is adopting this idea, that science and particularly the social sciences, are not about seeming right, but instead, being truthful.

     -Eric Johnson, Norman Eig Professor of Business, director of the Center for the Decision Sciences at Columbia Business School

The Mentor I Never Met

Daniel Kahneman is the most influential person in my career who I’ve never meet; his academic partner, Amos Tversky, is a close second. 

As an undergraduate prospective economics major, I believed I was a fairly rational thinker, until I learned about their work. Simple and elegant, their studies exposed our innate irrationalities. I realized that I too would judge the prevalence of words ending in -ing as greater than words ending in -_n_, because the former is easier to recall. Or that I would be more likely to take a risk when a problem was framed as a chance to avoid a large loss than when the equivalent problem was framed as a potential large gain.

Kahneman’s pioneering research in judgment and decision-making was a big part of the reason that I abandoned economics and ultimately pursued a career exploring consumer choice. His papers from all stages of his career continue to inspire my work. He will be sorely missed and I deeply regret never having met him.

     -Elizabeth Friedman, assistant professor of Business at Columbia Business School