Enlargement and the anticipatory deepening of European integration

It has often been argued that widening and deepening within the European Union are at odds. However, in practice enlargement episodes have repeatedly been accompanied by new deepening initiatives. I offer an explanation for this apparent puzzle by outlining a logic of anticipatory deepening. Current EU member states will have some expectations about the European policy preferences of accession candidates. These, combined with information about the preferences of existing member states, make it possible to compare pre- and post-enlargement bargaining and voting outcomes. Those member states that prefer the former thus have an incentive to negotiate deepening outcomes before the voting balance in the Council of Ministers shifts against them. I illustrate the logic with a simple spatial model, and test it empirically in two key episodes of pre-enlargement deepening: the 1969 summit in The Hague and the pre-Maastricht IGCs of 1991.