The Completeness of Public Reason

A common objection to the idea of public reason is that it cannot resolve fundamental political issues because it excludes too many moral considerations from the political domain. Following an important but often overlooked distinction drawn by Gerald Gaus, there are two ways to understand this objection. First, public reason is often said to be inconclusive because it fails to generate agreement on fundamental political issues. Second, and more radically, some critics have claimed that public reason is indeterminate because it cannot provide any citizen with sufficient reason(s) for making important political decisions. Against the first of these objections, I argue that the purpose of public reason is not to end reasonable disagreement. Rather, it is to provide a suitable framework of values and principles within which citizens may resolve their moral and political differences. Against the second objection, I argue, first, that the indeterminacy of public reason is much less common than its inconclusiveness; and, second, that there are second-order decision-making strategies that may enable citizens to cope with cases of indeterminacy. The incompleteness of public reason, whether it takes the form of inconclusiveness or indeterminacy, is not a reason for citizens to abandon their commitment to public justification.