This Article uncovers the normative political theory underlying the legal doctrine of constitutional pluralism, as it is used in the EU today. Constitutional pluralism, once described as a semi-official legal doctrine in the EU, is now being used by some member states to challenge its authority and rules. By reconstructing the political thought of one of its founders, N. MacCormick, this Article takes issue with two most common interpretations of constitutional pluralism: On the one hand, it has been claimed that the normative political content of constitutional pluralism is virtually identical, or at least compatible, with that of Kantian rights-based cosmopolitanism; on the other, it has been contended, especially with regard to its uses in Hungary and Poland, that it was an inherently dangerous, illiberal, normative theory. This Article offers to move away from current legal debates to go back to the origins of constitutional pluralism. It argues that constitutional pluralism is not a purely liberal theory indeed. But neither is it inherently illiberal. Rather, both liberal and illiberal readings are possible, but partial, interpretations of MacCormickian constitutional pluralism. A more systematic interpretation shows that constitutional pluralism opens a path to move beyond this somewhat archetypical divide.