The multiple crises of recent years—including the Eurozone crisis, the refugee crisis, and Brexit—together with the growing mobilization of anti-European political forces and movements have called into question the very existence of the EU and the project of integration. In this new context, the mere defense of the status quo is unpersuasive, at the same time that it seems no longer possible to promote integration by stealth. The populist challenge has to be faced head on, acknowledging that the current governance of the EU is the source of the anti-European malaise. If the status quo is unsustainable, then a discussion about the future of the EU is necessary.

Indeed, in recent years, scenarios for the future of the EU have proliferated in the political sphere as well as in academia and policy venues. Debates in recent election campaigns in Austria, the Netherlands, France, Germany, and Italy all addressed questions about how to deal with the future of European integration. Scenarios were even included in the Rome Declaration, signed by all the EU member state heads of government, together with the leaders of the EU institutions, on March 25, 2017 (on the occasion of the 60th anniversary of the 1957 Rome Treaties), acknowledging the necessity of opening a discussion on the future of Europe. Considering possible scenarios for the future of the EU has also become a topic of investigation in think-tanks and academic institutions. Policy analysts and scholars have written policy briefs, op-eds, and academic comments on how to move forward.

The academic debate, with its spillover into the political debate, has mainly focused on ‘differentiated integration’ for the EU. Differentiated integration raises substantial theoretical as well as practical questions about the how to maintain EU cohesion and coherence as well as the legitimacy and transparency of EU decisions where the future of the EU’s integration’s project becomes increasingly differentiated. Much of the discussion on differentiation has now coalesced around the idea of a multi-speed Europe in various forms and guises. But what kind of multi-speed EU remains in question, along with how it might work, which countries would be faster moving, and what form the EU might take moving forward.

This Special Issue investigates differentiation in several policy areas. After a theoretical discussion by Frank Schimmefennig on differentiation as a choice by national governments, subsequent articles consider the possibilities, the implications, and the limits of differentiation in a range of current policy areas in crisis. Ariane Chebel d’Appolloni considers the current problems of migration policy and border controls, and what would be needed to ensure common solutions while allowing for differentiated implementation. Christopher Bickerton develops differentiation further, to suggest a connection between Brexit and the rigidity of labor mobility in the Single Market. These crises area have had vast consequences for the future of the EU. The migration and refugee crises have triggered a populist upsurge. But solutions remain elusive, stymied by the vast divergences among member states on these issues (particularly Eastern Europe versus Western Europe) with regard to politics and identity. Brexit has challenged the Single Market’s four freedoms, which continue to remain at the foundations of any future EU, however differentiated. Brexit also poses another set of questions for the future of a differentiated EU. Matthias Matthijs, Craig Parsons, and Christina Toenschoff discuss the economic policy of the Eurozone and the Single Market in comparative perspective, showing that integration in these policy areas has been much deeper than in a federal system like the USA, with the dangers of Grexit and the realities of Brexit the result. At its turn, if Daniel Kelemen argues, in his article, that differentiation has its limits in the rule of law, since the latter constitutes the very legal foundation of the EU, the opposite happened in the area of Common Security and Defense Policy (CSDP) analyzed in the article by Jolyon Howorth. The latter area has been characterized by a lack of institutional deepening, as it has instead developed in the Economic and Monetary Union (EMU). How CSDP develops in the context of declining transatlantic solidarity, if it does, could lend insight into a new kind of differentiated integration.

The Special Issue discusses also what lies beyond differentiation. The issues here involve not just how EMU may evolve—with more, or fewer, members—but also how that evolution may itself have a determining impact on the future of European integration itself, for better or for worse. The two concluding articles enter directly in the theoretical debate on the future of Europe. That debate conceptualizes the future of the EU as a continuum. On one side of the continuum are those who assume that a ‘multi-speed’ Europe means that EU member states will move in the same direction or at least toward the same goal, even if at different speeds. On the other side are those who raise the possibility of a sort of decoupling of the current EU, on the evidence that EU member states pursue different finalités. They therefore distinguish between those member states pursuing a closer political union and those member states willing to accept only economic integration, although all are united by their participation in the Single Market. Scenarios for the future run the gamut from a ‘hard core’ Europe around a restricted number of countries, as argued by Sergio Fabbrini, through soft cores of overlapping memberships in different policy communities, as argued by Vivien Schmidt, all the way to a very loose confederation.

The big question for all such scenarios is how the future EU would work in practice, whatever the expected kind and degree of integration. This opens up a whole slew of further queries, including: How would the different ‘communities’ of the EU interact, whether conceived of in terms of a hard core, a soft core, or a loose confederation? Would there be one set of institutions or many? What would the obligations of the different member states be, whether in terms of budgetary contributions, common security arrangements, or solidarity relationships? What normative principles might bind the member states together—continued adherence to democratic norms and a sense of a common destiny, or only market relations and common geography? And what are the implications for legitimacy? In additional to such general questions about the possible futures of EU differentiated integration, more specific issues come up for any given policy area. Proceeding from the assumption that any given policy area will need to develop adapted policies and institutions to cope with the challenges raised by the EU’s many crises, how would the different possible scenarios—hard core, soft core, or loose confederation—affect the organizational capacity and potential success of any initiatives undertaken in that area? Such queries are especially important for the key issue areas affected by the EU’s major crises. How the EU develops in each of these policy areas can have very serious implications for future development. And here too, how these policy areas develop in the near term—and whether they resolve the crises or allow them to continue to simmer—also has a lot to do with how the EU as a whole moves forward with regard to its own differentiated integration—hard, soft, or loosely confederated.

This Special Issue thus proposes to contribute to the debate on the future of Europe by starting from the literature on differentiated integration but moving beyond that. It brings together major scholars whose views differ on what such multi-speed EU futures might look like, how they would function, and how they might evolve. As it is this debate, also Europe’s future seems to be plural.