Cass Sunstein


Nudging Behavioral Science and Policy Closer Together


It seems as though Cass Sunstein’s voice can be heard reverberating everywhere – from law and policy to behavioral science, from health and teaching to legal consulting. Sunstein’s ability to transmit complex ideas into simple examples- such as his suggestion that Star Wars reflects real-life issues – has gained him great popularity. He has published over 40 books on a range of topics, with his most popular being Nudge, co-authored with Richard Thaler.

Since his early days, Sunstein has been interested in where behavioral science and policy intersect and how policies can be used to improve people’s lives.

Just as no building lacks an architecture, so no choice lacks a context.

– From Cass Sunstein and Richard Thaler’s book, Nudge1

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In 2008, Sunstein co-authored Nudge: Improving Decisions about Health, Wealth and Happiness alongside Richard Thaler. The book is considered one of the leading texts of behavioral economics. Sunstein and Thaler based their insights on the concept of ‘bounded rationality’ developed by Daniel Kahneman and Amos Tversky. Bounded rationality suggests that people’s ability to make optimal decisions is constricted by time, available information, and brain capacity. Instead of making perfectly rational decisions, people make satisfactory decisions as a result of their limitations. Sunstein and Thaler applied this idea to policy.2

The book describes the fact that people are not the best judges of what is optimal or what decisions will best serve them, which leaves room for institutions like the government to help guide people toward optimization. The tools that governments can use are known as nudges and are small elements of choice architecture that manipulate a decision-making environment and push people toward a specific decision. The book was an elaboration of the idea of libertarian paternalism, which built on a paper that Sunstein and Thaler had written in 2003.2 Libertarian paternalism suggests that it is possible – and ethical – for governments to influence behavior while not hindering people’s freedom of choice. The pair wanted to defend nudging, as they state, “it is no longer paternalistic to nudge people, because you are not (simply) protecting them from themselves; you are protecting others from them as well”. 1

Sunstein and Thaler also believed that it was impossible to make decisions without environmental influences. There will almost always be factors external to the process of decision-making that influence the outcomes of these decisions. What became important for Sunstein and Thaler was figuring out how choice architects can present options as neutrally as possible, or alternatively, to nudge people in a direction that is beneficial for themselves and society.3


From Groupthink to Collective Intelligence

Sunstein acknowledges that almost as long as people have been alive, we have been making decisions as groups. The belief is that the more opinions at the table, the better chance a group will have of making an optimal decision. However, haven’t we also heard of the phrase ‘too many cooks in the kitchen’?


This is where groupthink comes in. Groupthink describes people’s tendency, when in a group, to conform to the majority opinion rather than to think individually. We are influenced by social proof, which means we tend to follow the masses, and also by herd behavior which can actually cause us to make worse decisions when in a group setting than alone.


In an article for the Harvard Business Review, Sunstein mentions a host of other cognitive biases that cause groups to go wrong in their decision-making. These tendencies can have significant impacts. As he states, “if a project, a product, a business, a politician, or a cause gets a lot of support early on, it can win over a group even if it would have failed otherwise.”4


What is of most interest to him, though, is whether groups can avoid these pitfalls and limit the influence of their cognitive biases. Sunstein outlines six different ways that people can surpass the trials and tribulations of groupthink and move towards collective intelligence. Collective intelligence still incorporates group participation, however, realizes that different people should take on different parts.4 Sunstein’s advice is as follows:

  1. Silence the leader, because when a leader expresses their opinion early on, people are likely to agree with them.
  2. Prime critical thinking, which can be achieved by giving individuals a task that requires them to turn their brains on as they enter the group.
  3. Group success should be rewarded, rather than individual success. People sometimes don’t offer up their ideas because they don’t get to reap the benefits of a group’s decision.
  4. Assign each individual a role, which makes each person feel as though they have something valuable to contribute.
  5. Appoint a devil’s advocate, so that even if the entire group is in agreement, one person has to take the other side, which can address some counterarguments people are too scared to bring up.
  6. Employ the Delphi method, where people are asked to first give an opinion anonymously and the group then has to discuss the opinions and recast their ‘votes’ or ‘opinions’ within a 25-75 range percentile of the original group average.4

The World According to Star Wars (and Cass Sunstein)

One of Sunstein’s very well-known works is his 2016 book The World According to Star Wars. Sunstein wrote the book in order to capture the attention of the everyday audience and use the renowned film as a metaphor for different elements of real life.

Sunstein explores why Star Wars enjoyed such a widely unanticipated success and gives insights as to some general causes for success and failure. Sunstein identifies three factors: quality, timing and social influences. In an interview, Sunstein suggested that these factors don’t just explain the success of films but might also explain why a controversial figure like Donald Trump was elected President.5 He claims that Star Warsshows that in a time of division and polarization, a lot of people like a Tough Guy”.5 Moreover, Sunstein touches on the idea of social proof and social norms. Once Star Wars was believed to be popular, other people began to rave about it because they believed that this was the appropriate response. Similarly, Sunstein suggests that once Trump seemed popular, he earned more votes since people thought other people were voting for him.5

Ultimately, Sunstein suggests that too often, success or failure is unpredictable.6 Unlike economic models that suggest that you can carefully calculate the trajectory of a product or an idea, Sunstein’s ideas resonate with behavioral science and therefore suggest that things only seem predictable in hindsight. He uses the example of Harry Potter being turned down by twelve different publishers and going on to being one of the greatest book series of all time.6 By showing us the unpredictability of pop culture products, Sunstein acknowledges that there are so many different variables and cognitive biases that impact people’s decision making that humans cannot be said to operate rationally.

Additionally, as Sunstein reveals in an interview with his daughter, Star Wars resonated with so many people because it accurately captures the gray areas of ‘right’ and ‘wrong.’7 Neither Darth Vader nor Luke Skywalker fit neatly into either category. As a father-son duo, the two characters also reveal the complexity of fatherhood and the complicated relationships parents often have with their children.7

Historical Biography

Cass Sunstein was born September 21st, 1954 in Massachusetts. His father was a builder and his mother a teacher. Early in his teen years, Sunstein showed an interest in philosophy, becoming enamored with Ayn Rand, a novelist-philosopher.8 However, when he attended Harvard to pursue higher education, he studied Law and received honors in the Juris Doctor degree in 1975. While at Harvard, Sunstein was the executive editor of the Harvard Civil-Rights Liberties Law Review and held a position on the Board of Editors for the Harvard Lampoon, an undergraduate magazine publication.9

His undergraduate degree at Harvard was only the beginning of Sunstein’s immersion into law, which he complements with an interest in behavioral science. After his degree, Sunstein became a law clerk for the Supreme Court of Massachusetts in 1978 before moving on to becoming a law clerk for the Supreme Court of the United States.9 Sunstein then turned to teaching and was offered a position at the University of Chicago as an assistant professor of law. In 1985, he was offered a full position as a professor of law in Chicago’s Law School and Department of Political Science. He remains a visiting professor at the University of Chicago today, but his permanent post since 2008 has been at Harvard.9

Sunstein has had a big impact at Harvard and founded the Program on Behavioral Economics and Public Policy at Harvard Law School, concretizing the interdisciplinary nature of his research. He continues to be the director of the program today and has been awarded the Robert Walmsley University Professor title, a title which honors individuals who cross the boundaries of multiple disciplines and conduct groundbreaking work.10

Sunstein has also had various positions outside of academia. From 2009 to 2012, Sunstein was the administrator of the White House Office of Information and Regulatory Affairs.10 He has testified before congressional committees on a variety of subjects and has advised officials globally, including at the United Nations and World Bank.10 In 2020, Sunstein was appointed the chair of the World Health Organization’s advisor group on Behavioral Insights and Sciences for Health. He is also currently an adviser to the Behavioral Insights Team in the U.K., a company dedicated to improving people’s lives and communities.10


In his 2003 paper “Libertarian Paternalism,” Sunstein advocates for government involvement in nudging because “the presumption that individual choices should be free from interference is usually based on the assumption that people do a good job of making choices, or at least that they do a far better job than third parties could.” 14

He reiterates his position elsewhere, suggesting that without libertarian paternalism, “we might miss the real opportunities for a thoughtful, other-regarding reconciliation of two critical parts of our human nature: the desire to liberate and enable the individual, and the impetus to protect and serve the collective.” 15

It is all about striking the right balance, according to Sunstein. He says, “to put it simply, forcing people to choose is not always wise, and remaining neutral is not always possible”.16

On groupthink, Sunstein states that “when like-minded people get together, they often end up thinking a more extreme version of what they thought before they started to talk to one another.15

We might better understand Sunstein’s fascination with Star Wars if we consider his opinion that shared experiences are vital to a society’s success. He states in his book #Republic that “without shared experiences, a heterogeneous society will have a much more difficult time addressing social problems. People may even find it hard to understand one another. Common experiences, emphatically including the common experiences made possible by social media, provide a form of social glue. A national holiday is a shared experience. So is a major sports event … or a movie that transcends individual and group differences (Star Wars is a candidate)”.15

Where can we learn more?

We’ve discussed some of Sunstein’s more popular books, such as Nudge and The World According to Star Wars. You can find a list of some of his other published books here.

Here at The Decision Lab, we were lucky to have Sunstein as a guest on our podcast, “The Decision Corner.” In the episode, Sunstein focuses on the notion of ‘fun’ and how it relates to happiness, policy-making and political leadership.

One book that might be of particular interest these days is Conspiracy Theories and Other Dangerous Ideas. In this book, Sunstein examines why regular people are often susceptible to believing conspiracy theories.

If you were interested in Sunstein’s work on nudges and want to read beyond his book with Thaler, you may want to check out some of his subsequent books not included in the aforementioned list: Why Nudge? The Politics of Libertarian Paternalism and Choosing Not to Choose: Understanding the Value of Choice. These texts delve deeper into Sunstein’s concerns about the misuse of nudges as tools for manipulation and marketing, and thus the need to more closely examine choice architecture.17

Sunstein has also been a TEDx speaker and his lecture entitled “Saving Money and Saving Lives” can be found here. In his lecture, Sunstein discusses how nudges can be used to push people to make the best decisions for themselves in all regards, ranging from what is economically best to what is the best for our health.

He’s also been a guest on the podcast “The 80,000 Hours.” In the episode, Sunstein takes a deep dive into social change, examining the ways in which reformation and rebellion occur and become successful. In particular, he takes a look at how Trump was elected and why the Brexit vote was favored.


  1. Thaler, R. H., & Sunstein, C. R. (2008). Nudge: Improving decisions about health, wealth and happiness. Penguin Books.
  2. Schwartz, B. (2014, April 17). Why Not Nudge? A Review of Cass Sunstein’s Why Nudge. Behavioral Scientist.
  3. Richard Thaler. (2020, November 30). The Decision Lab.
  4. Sunstein, C., & Hastie, R. (2014, December 1). Making Dumb Groups Smarter. Harvard Business Review.
  5. Sunstein, C. (2016, May 30). Trump, Social Media, and Predicting Success. Interview by B. Thurston. Medium.
  6. Talks at Google. (2016, July 28). The World According to Star Wars | Cass R. Sunstein | Talks at Google [Video]. YouTube.
  7. Sunstein, C. (2016, June 3). An Interview With My Father, Cass Sunstein. Interview by E. Kail. Huff Post.
  8. Sunstein, C. R. (2020, April 9). The Siren of Selfishness. The New York Review of Books.
  9. The University of Chicago Law School. (n.d.). Cass R. Sunstein : Curriculum vitae. Wayback Machine. Retrieved January 18, 2021, from
  10. Harvard Law School. (n.d.). Cass R. Sunstein. Retrieved January 18, 2021, from
  11. Helgesen, S. (2017, June 7). It’s All Cass Sunstein’s Default. Strategy + Business.
  12. Jacobs, A. J. (2009, September 9). Cass Sunstein and Samantha Power: Fun Couple of the 21st Century. Esquire.
  13. Wallace-Wells, B. (2010, May 13). Cass Sunstein Wants to Nudge Us. The New York Times.
  14. Thaler, R. H., & Sunstein, C. R. (2003). Libertarian paternalism. American Economic Association, 93(2), 175-179.
  15. Goodreads. (n.d.). Cass R. Sunstein Quotes. Retrieved January 18, 2021, from
  16. Goodreads. (n.d.). Nudge Quotes. Retrieved January 18, 2021, from
  17. Kinni, T. (2016, February 24). Cass Sunstein’s Required Reading. Strategy + Business.

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