The ideal of reason is central to contemporary accounts of citizenship in American constitutional law. The individual capacity for reasoned choice lies closely aligned with the constitutional values of personal liberty and democratic self-government as they have evolved in Supreme Court decisions over the past century. Yet as presently conceived, the ideal of reason in constitutional law overlooks the process by which individuals actually acquire the capacity to choose their own values and commitments or to engage in reasoned thinking about collective ends. This paper argues that we cannot hope to sustain and foster a constitutional polity committed to the principles of individual liberty and democratic self-government without knowing somet...