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Remembering Danny Kahneman: Reflections from David Halpern

28th Mar 2024

This week we had the sad news of the death of Danny, a truly monumental figure in behavioural science. He was an inspiration and massive influence on me personally, on the work of the Behavioural Insights Team, and on many of my generation. He was a regular visitor to BIT in its early days, with seminars and discussions with him at No10, Treasury, and more publicly at the Behavioural Exchange conferences. We also worked with him on the ‘wellbeing’ or happiness agenda, including his pioneering work on measurement. As tribute, we have posted here a discussion between Danny and Richard Thaler (later to receive his own Nobel) at BX2015.


I first came across Danny’s work, along with that of his longtime collaborator Amos Tversky, while studying Experimental Psychology at Cambridge in the mid 1980’s. Their work on Judgement under conditions of uncertainty (1973) and breakthrough paper in Science on  Heuristics and Biases (1974) stood out from the field. Most cognitive psychology at the time was either very high level theory, often resting rather unconvincingly on computational metaphors of the time, or was highly specific and in the weeds (such as very detailed effects in memory).

Danny and Amos’s work in contrast was both highly empirically grounded, and offered a set of theories and effects with immediate and widespread implications. For example, ‘anchoring effects’ showed subjects’ answers to questions were strongly ‘anchored’ to arbitrary priors: how many countries are there in the world (say 20?). It also had immediate practical implications. Going for a pay rise? Or negotiating a sale? Start by introducing a large $ reference point.

It took a few years before the importance of Danny and Amos’s work broke out of psychology. Interestingly, it was a hole at the heart of economics that propelled Danny to global fame and impact. Economics had great maths and great minds, but almost every economics seminar and paper started with a fiction. ‘Let us assume that…’ then followed a series of simplifying and implausible assumptions about human behaviour and cognition. 

Danny’s work exactly fitted into that hole. A description of actual human decision making, and with enough specificity that you could plug it into a mathematical model.

I first met Danny in person in the early 2000’s, when I was Chief Analyst at Tony Blair’s Prime Minister’s Strategy Unit (PMSU). He had yet to win his Nobel Prize. Though Prospect Theory and a growing following in economics was raising his profile, he was far from a household name. We were working on a paper in the PMSU on Behaviour Change, and I was keen to draw him in for a chat. Geoff Mulgan, the then head of the PMSU, joined us.

Towards the end of our meeting, I asked Danny if there were any new papers or work in the field that he would especially recommend that we look at. ‘Yes’ he said, in the reflective manner that he never lost – he never tried to make up an answer, and had that rare quality of always being ready to say ‘I don’t know.’ ‘There is some very interesting work by a guy called Richard Thaler, and this idea of “libertarian paternalism’. 

Sure enough we followed Danny’s suggestions, including to early versions of Richard and Cass’s paper on Libertarian Paternalism (2003) and linked work on Save more tomorrow (2001, 2004). The former featured heavily in our PMSU paper on Personal Responsibility and Behaviour Change – now twenty years ago – as did heavy references to Danny’s own work. The latter, on pensions and saving, I stuck a hard copy and sent it to Adair Turner (who was leading our pensions review) with a scribbled note saying it was probably the most important paper he would read on the subject.

In the wake of the 2010 election, when we set up the Behavioural Insights Team in Cameron’s No10, Danny was an early visitor. I remember well a seminar we held with him in the Pillared Room in Downing Street. By this point, Danny was a big name, with the Nobel long since won.

We had a good turnout from within No10, with colleagues keen to ask him how to solve a whole range of tricky policy problems. Classic Danny, he courteously but firmly told most of them ‘I don’t know’. They were disappointed, but it was a humility that far more people – including in the policy world – would do well to adopt. The truth is, most of the time ‘we don’t know’. But most of us aren’t smart enough to realise it. Danny not only was smart enough, but also understood the significance of ‘I don’t know’ more deeply – that our brains are brilliant at coming up with plausible but potentially wrong answers.

On another occasion – this time at a bigger seminar we hosted with Danny in the Churchill Room in the Treasury, I asked Danny a question that had been bugging me for a while. People tend to think of fast brain responses as efficient but prone to error, but are there examples where fast brain (system 1) responses are actually much better than more reflective, slow brain responses (system 2)?

In response, he told a wonderful, and slightly strange personal story that always stuck with me. He told of when he was once walking by himself on a road. A car drove past him, slowed, and pulled up in front of him. Four guys got out of the car and started walking towards him.

Now Danny is not a big guy, and the situation didn’t look good. Then suddenly, Danny found himself screaming at them at the top of his voice, and waving his arms around. Evidently, the four guys were taken aback. They stopped in their tracks, turned around, got in the car, and drove off.

Danny reflected that he had no idea where this behaviour – his  screaming and arm waving – came from. It definitely wasn’t system 2. Something deep inside him came up with this behaviour in the moment. It was baffling to him, and yet it worked. Cool, weird, human beings.

If there was one area that did bug Danny a little bit, it was that economists seem to have got the credit for his work. I recall him talking about it as we were going into an event together in the White House. ‘It’s not behavioural economics! It’s psychology!’ I think he wanted a few more psychologists to follow in the arc of his arguments, including to pick on some questions where he felt he had to answer ‘I don’t know’.  In fact, Danny’s view was one of the reasons why we called BIT the ‘Behavioural Insights Team’ rather than the ‘Behavioural Economics Team’; he would never have forgiven us!

Yet of course Danny had a warm and deep relationship with many economists, and so many other disciplines, not least with BIT longtime friend Richard Thaler, who you can see interviewing Danny in the video clip above. What seemed to matter much more to Danny was a deep curiosity about the human mind, and to have collaborators with whowrestle with these issues (empirically if possible!)

Thank you Danny. For the leap and insights that you brought. We will miss you.