 This entry is structured around questions about the nature of public reason that continue to be the subject of sustained debate in the literature. Section 1 considers competing positions regarding the underlying rationale for public reason. Section 2 identifies different views about the appropriate scope of public reason. Does it apply to all moral rules, only to political rules, or only to some sub-set of political rules? Section 3 considers the question of public reason’s constituency: to whom must our rules be justifiable in order to be considered legitimate or authoritative? The next question, in section 4, concerns the content of public reason; in particular, to what extent is this content determined via a process of philosophical reflection as opposed to actual moral deliberation? Section 5 considers the structure of public reason, with particular focus on whether public reason requires some shared perspective or set of considerations, or whether it can be achieved without any common moral or political perspective. Section 6 addresses the site of public reason: where do its norms properly apply and when do they regulate individual conduct? Section 7 identifies some of the most influential objections that have been pressed against the idea of public reason, and Section 8 concludes with a brief survey of a few further topics.