Modern constitutional democracy entails a particular kind of political self-understanding that uniquely centers on a constitution. While many recent studies have focused on how constitutional text shapes this self-understanding, little attention has been paid to the implications of different views of constitutional authority. This is a critical consideration, however, because constitutional authority has always been intrinsically fragile within constitutional democracy, and never more so than at present. In this article, I explore the potential of constitutional science to generate a conception of constitutional authority and collective identity. I focus on David Hume's effort to use constitutional science to shape opinion about liberty and the nature of the political community. This analysis also provides a basis for reflecting on the problematic relation of democracy to constitutionalism and on the peculiar problem of constitutional opinion in constitutional democracy.