Our central claim in this rejoinder is that experimentalist forms of organization in making regulatory rules, organizing social services, and articulating constitutional norms arise and diffuse as the problem that the actors and the state face shifts from ignorance to uncertainty. We argue that this has consequences for forms of accountability and for the conception and organization of democracy and constitutionalism. The EU, founded by diverse states in a period of continuing uncertainty, intensified by growing interdependence, proves to be a natural laboratory for observing urgent efforts to adjust to this new situation, and the symposium focuses on developments there. The symposium has brought us to see that there is more common ground in these debates than prior exchanges may have suggested. We therefore emphasize convergence on large points, while underscoring and, we hope, clarifying persistent differences, with the aim of encouraging the joint exploration of them already underway, in part explicitly, in part implicitly.