Justifying the Imperfect: Differentiated Integration and the Problem of the Second Best

This article deals with the problem of the second best in a politically differentiated Europe. Drawing on Kant’s category of permissive law of public right, it establishes the missing link between ideal and nonideal theory and then an indirect legitimation theorem . This theorem provides tools to contain damages and unlock practices and dynamics that obstruct reforms and lead to counterproductive outcomes. The theorem, which is equipped with a time and knowledge index, awaits the formation of favourable circumstances of integration. It establishes the conditions under which differentiated integration would be nonregressive. The theorem rules out backsliding solutions, which undermine the European integration process.