Cass R. Sunstein is the founder and director of Harvard University’s Program on Behavioral Economics and Public Policy. He is also a world-renowned legal scholar and an extraordinarily prolific author. He is best known as the coauthor (with Richard H. Thaler) of the 2008 best-selling book Nudge: Improving Decisions about Health, Wealth, and Happiness. Reference Sunstein and Thaler¹ Since then, Sunstein has authored or coauthored countless journal articles and three other books that reiterate and expand on what Sunstein and Thaler originally referred to as “libertarian paternalism.” Those three books are Why Nudge: The Politics of Libertarian Paternalism,Reference Sunstein²The Ethics of Influence: Government in the Age of Behavioral Science,Reference Sunstein³ and Human Agency and Behavioral Economics: Nudging Fast and Slow. Reference Sunstein⁴ It is noteworthy that these three accounts of libertarian paternalism build on a common conceptual framework and cover similar ground.

In 2018, I contributed to a multiauthor forum in Politics and the Life Sciences (PLS) that explored a framework that we called “nudge science.”Reference White, White, Kroncke, Sankowski and Vanderburgh⁵ Covering issues such as economics, ethics, and health policy, the contributions to that forum discussed the relevance of nudge science for biopolitics and for the social sciences in general. This review will build on the conceptual framework explored in those contributions, especially my introductory essay.Reference White⁶ Henceforth, I will refer collectively to these earlier works as “nudge science.”

On Freedom is a tiny book, 5 by 7 inches with 118 pages of narrative. Like all of Sunstein’s books, it is well crafted, easy to read, and interesting, and it targets both scholarly and popular audiences. This review will address two main questions. First, how much of On Freedom elaborates on the conceptual framework of nudge science published in the PLS forum, and how much (if anything) is altogether new and a worthwhile addition to that body of work? Second, in light of these first two answers, who (if anyone) would be interested in this book, and what (if anything) would they get out of it?

The title On Freedom is a direct reference to John Stuart Mill’s classic work On Liberty (1859),Reference Mill⁷ which is widely regarded as the primary source of antipaternalism within the classical liberal tradition. For Mill and his libertarian followers, legally restricting the liberty of a rational and competent adult to provide an unwanted benefit or to prevent self-induced harm is, a priori, unacceptable. Nudge science (including On Freedom) revisits that argument and asks, under what circumstances (if any) can a liberty-loving, self-governed society deploy bans, mandates, and nudges to promote the welfare of rational, competent adults without their consent? Nudge science has consistently argued that there is more room for paternalistic intervention within the classical liberal tradition than most libertarians are willing to acknowledge.

So how do we go about morally evaluating the ethics of governmental actions? In his previous book, The Ethics of Influence, Sunstein argued that government actions must be evaluated in light of four often-conflicting valuesReference Sunstein³—that is, by asking whether the action under consideration “increases welfare, promotes autonomy, respects dignity, and promotes self-government” (p. 53).

On Freedom focuses primarily on the moral conflict between the principles of autonomy (freedom) and welfare conflict (well-being) developed in The Ethics of Influence. Mill and most classical liberals would argue that individual freedom of choice necessarily promotes the human well-being of both individuals and the collective. After all, rational, competent adults are the best judges of what will or will not promote their own well-being, and therefore they should be allowed to go their own way, so long as they do not harm others (p. 3). On Freedom challenges several key aspects of that libertarian argument.

Nudge science reexamines freedom of choice in light of the recent findings of social science, namely, that all of our “choices” are influenced (if not determined) by choice architecture, erected by either Mother Nature or by individuals and groups within our sociopolitical environment. Our vulnerability to the influence of competing choice architects has been enhanced by advancements in behavioral economics, especially the discovery of “behavioral biases” and other fallacies that predispose us to make choices based on predetermined patterns, including present bias (our natural tendency to pursue our immediate, short-term personal well-being, often at the expense of our long-term well-being). So, whether we are consciously aware of it or not, we are constantly being “nudged,” often by competing choice architects. Not all of those architects seek to advance our personal welfare. Many nudge us one way or another to benefit themselves, their family, or their friends. Sunstein argues that if all of our choices are nudged by choice architects, and if many of those nudges are hostile to our welfare, then welfare-advancing political nudges are, obviously, morally preferable to welfare-invading nudges.

On Freedom, therefore, argues that under conditions of self-government, the state can (and ought to) nudge us toward advancing our personal welfare. But this raises a number of long-standing libertarian issues. How can well-meaning choice architects know whether their paternalistic interventions will (in fact) advance our well-being? Sunstein argues that the value of welfare-enhancing nudges can only be assessed by the intended beneficiary. But when? Before the benefits are experienced or after? If after, how long after? Thus, Sunstein points out that the “as judged by themselves” principle contains hidden complexities. For example, prior to being nudged, drug and alcohol addicts might object to being nudged away from those freedom-reducing addictions, but most of us would not, subsequently, object to having been nudged away from those addictions or having been nudged toward eating healthy foods, exercising regularly, donating our organs, or saving toward retirement.

So what, if anything, does On Freedom contribute to the lexicon of nudge science? Sunstein introduces two innovative features: one is stylistic, the other more substantive. Stylistically, On Freedom is different from his earlier books, in that he employs several expository case studies to reveal hidden complexities. He also uses several illustrative examples drawn from classic literature. His recent interest in drawing on works of popular culture is reflected in another recent best-selling book, The World According to Star Wars. Reference Sunstein⁸ Neither of these stylistic innovations is particularly problematic. However, at least some scientists and philosophers will be less than enthusiastic about his expository references to the arts and humanities.

On Freedom’s more substantive innovation consists of introducing a new set of “navigational metaphors” intended to clarify and expand on his earlier “architectural metaphors.” As Sunstein puts it, “Obstacles to navigability have been the great blind spot in the Western philosophical tradition?” (p. 2).Footnote ^a Therefore, the overriding question addressed in On Freedom is whether the institutions of democratic government can effectively help us navigate the architectural maze of modern life without violating our personal autonomy. Sunstein argues that the effectiveness of our individual pursuit of well-being requires more than freedom of choice. We must also be able to navigate our way through an ever-growing maze of architectural variables.

At first glance, Sunstein’s metaphors, such as “navigation” and “navigators,” seem to elucidate nudge science. Suppose, based on my own current interests, I decide to take a vacation in Hawaii. I know where I want to go, but I lack the navigational knowledge and skills necessary to get there. Thus, I might willingly choose to employ an airplane pilot, rather than, say, a cruise ship pilot. But to what degree does life, in general, resemble a voyage? The expanded use of navigational metaphors suggests that life is about “going somewhere” (either literally or figuratively), that we know where we want to go, and that we willingly employ skilled navigators to help us get there. So far, so good. However, the closer we look at these navigational metaphors, knowledge problems arise. After all, there are more-skilled and less-skilled navigators, and we do not always know how to distinguish between the two. Even if our chosen navigators are skilled, we may not know whether they intend to employ their navigational skills to advance or undermine our individual welfare or the welfare of others.

Those navigational metaphors begin to break down when various kinds of institutionalized navigators (public/private) not only nudge us toward our chosen destination but also surreptitiously choose “where we want to go.” Most of us would not object to being reminded of the likelihood of volcanic activity in Hawaii, which may or may not influence us to change vacation plans. But those metaphors irrevocably break down when that navigator possesses the knowledge and ability to surreptitiously “nudge” us toward an alternative destination. To what extent do those navigators violate our autonomy when they nudge us toward that alternative destination, even if it might improve our well-being? Do those actions contradict the very concept of a navigator?

Sunstein argues that in a democratic society, navigators often violate our autonomy when they employ the coercive power of legally enforced bans and mandates to increase our self-regarding welfare interests. So while coercive bans and mandates can play a role in a liberty-loving society, they must be limited to preventing harm to others. However, according to Sunstein, welfare-enhancing nudges are noncoercive, autonomy preserving, and morally acceptable. Additionally, when that navigator violates our autonomy by taking us places we do not want to go, in order to advance our personal welfare, we might subsequently prefer “by our own lights” that alternative welfare-enhancing destination. Life can be either easy or difficult to navigate, depending on the choice architecture that underlies our choices. Helpful choice architecture simplifies navigation. Sunstein’s overall claim is that government can play a role in “nudging” us toward decisions that advance our individual well-being.

So what, exactly, does the Sunstein’s use of navigational metaphors contribute to nudge science? Do those metaphors elucidate or obfuscate the autonomy-welfare conflict? Most nudge scholars will agree that beyond the introduction of those navigational metaphors there is not a lot of new philosophical analysis or research within its pages. Pundits will question whether mixing those “architectural” and “navigational” metaphors elucidates or obfuscates nudge science.

Unfortunately, for those of us looking to Sunstein for deeper insight into politics and the life sciences, there’s not a lot there. But there are ample opportunities for the rest of us to take nudge science to that higher level of analysis. For readers interested in an explicit discussion of the implications and applications of nudge science for the study of politics and the life sciences, I recommend the perspective pieces by Kroncke,Reference Kroncke⁹ Sankowshi,Reference Sankowski¹⁰ Vanderburgh,Reference Vanderburgh¹¹ and White.Reference White¹²

Despite the fact that some critics will ultimately object to its stylistic or substantive innovations, most audiences will appreciate and benefit reading On Freedom. Scholars who are actively engaged in nudge science will appreciate it as an up-to-date summary of the four previous works published in PLS that explore nudge science. Social scientists, philosophers, and readers of popular science who have not yet explored nudge science will certainly benefit from On Freedom as a concise, well-written, and up-to-date introduction. In the final analysis, although this little book really does not break new scholarly ground, it will serve as a brief, inexpensive, and well-crafted summary of the current state of nudge science. On Freedom is, therefore, a suitable addition to an introductory or undergraduate course on decision-making.