The Brexit puzzle: polity attack and external rebordering.

Brexit constitutes a puzzle for integration theory. Functionalist analyses have not only failed to predict the UK's exit but have also underestimated the disintegrative dynamics of the withdrawal negotiations. By contrast, postfunctionalism accounts for the disintegrative Brexit process but struggles to explain the unity and defence of supranational integration among the EU-27. This article tries to make sense of the Brexit puzzle. First, it argues that Brexit constitutes an attack on the EU polity rather than a policy failure - the type of crisis that functionalist theories explain best. Second, it complements the postfunctionalist account of domestic politicisation with an analysis of the reactions and strategies of the defenders of supranational integration. According to this expanded postfunctionalist analysis, the interaction of polity attack and polity defence has produced 'external rebordering': extreme disintegration of the UK from the EU, on the one hand, and strengthened integration of the EU-27, on the other.