UC Berkeley

Public reason theorists argue that it is permissible for the state to enforce political norms, such as laws or constitutional principles, when those norms are acceptable to “reasonable people.” Reasonable people are neither actual people, with all their flaws, nor are they perfect people; they are rather a partially idealized group – realistic in some ways and idealized in others. Each of the major public reason theorists – John Rawls, Gerald Gaus, Jonathan Quong, Joshua Cohen – idealizes reasonable people to a different degree, but they all share two claims: 1) Reasonable people hold diverse views of the good life. Nevertheless, 2) Reasonable people can all accept basic liberal political norms grounded in freedom and equality.

My dissertation begins by arguing that theorists are not free to choose any level of idealization, but are constrained in this choice by the justifications of their theories. In particular, idealization is constrained by one essential part of public reason’s justification, which I call the “diversity argument.” The diversity argument explains the first element of reasonable people: why do they disagree about the good? The answers, I argue, attributes certain realistic qualities and tendencies to reasonable people, which therefore constrains how much we can idealize them.

In chapters on the major public reason theorists, I argue that they all offer a diversity argument that does not match the level of idealization that they employ. As a result, they are unable to show that liberal norms are acceptable to reasonable people, appropriately idealized. In the final chapter, I argue that the mismatch in these theories goes even deeper, which we can see when we ask why we must accommodate disagreement at all. The answers that philosophers have given us – reasonable disagreement is the inevitable result of human reasoning, human psychology, or free conditions – also apply to irrational disagreement. Irrational influences such as implicit bias and motivated reasoning are also inevitable results of who we are and how we live, which means we must accommodate these realistic tendencies in political justification.

So, if public reason theories must now accommodate disagreement among reasonable-but-sometimes-irrational people, what could be acceptable to all such people? I conclude by suggesting a new direction for public reason theories. People who disagree about the good life, but recognize their common biases, can still justify their views to each other by supporting institutions that mitigate those biases, such as non-discrimination laws and deliberative institutions. This requires a new kind of social contract theory – one that is grounded in the shared recognition of our limitations, rather than our shared reasons.