The Causes and Modes of European Disintegration

This thematic issue on the causes and modes of European disintegration seeks to answer two main questions: What are the causes of (potential) European disintegration across countries? And what are the actual and potential modes of European disintegration? The articles on the causes of EU disintegration go beyond the immediate causes of Brexit, to date the prime example of European disintegration. They address, for instance, the impact of ignoring the results of referendums on EU treaty changes. The articles demonstrate that the extensively studied proximate causes of Brexit may be different from more long‐term drivers of potential disintegration in the UK and other member states. The second question raises a point that has been largely overlooked. Going beyond the growing literature on Brexit, differentiated integration, and non‐compliance, the articles on the modes of European disintegration address issues such as (temporary) opt‐outs from the Schengen agreement. The thematic issue is innovative not only due to the questions it raises but also by deploying a multi‐disciplinary social science perspective. Contributions are quantitative, qualitative, and theoretical from a wide array of social science disciplines. Taken together, the contributions to this thematic issue advance scholarly understanding of European (dis)integration.


Introduction
Before Brexit, the EU had only grown in terms of member states and depth of integration (Hooghe & Marks, 2019;Huysmans, 2019). On the one hand, Brexit has called into question the idea of an ever-closer union. On the other hand, support for EU membership seems to have gone up in the remaining member states, pointing at clear deterrence effects (De Vries, 2017;Walter, 2021), and the potential for deeper integration and collaboration among the remaining EU member states has improved. Moreover, countries in the Western Balkan and Ukraine have shown a clear interest in joining the EU.
This thematic issue investigates the causes and modes of European disintegration beyond the particulars of Brexit. Are other European countries likely to try to reverse certain aspects of European integration? If so, what causes this and how could they envision exiting (partially or fully) from certain aspects of European integration? How are these disintegration pressures addressed in different member states?
(Dis)integration processes result from potentially politicized cost-benefit assessments of international cooperation (Gastinger, 2021). For a long time, attempting to raise efficiency and attaining economies of scale within the European Union mainly favoured further integration (for political economy theories on the optimal size and scope of federations see, e.g., Alesina & Spolaore, 2003;Huysmans & Crombez, 2019). In recent years, Eurosceptic, populist, and nationalist movements have questioned the size and distribution of these efficiency gains and the EU's output legitimacy, while politicizing the costs and questioning the legitimacy of integration in terms of a loss of autonomy and sovereignty (de Wilde & Zürn, 2012;Jones, 2018;Vollaard, 2018).
In response to differences across member states, the EU has engaged in differentiated integration. Some member states have the euro, others do not; some are part of Schengen, some are not. This allows like-minded member states to move forward while keeping others within the existing structures. Complementary to differentiated integration, this thematic issue focuses on disintegration, i.e., reversing some aspects of European integration. The results may be similar to differentiated integration, but the mechanisms leading to a reversal of integration are different than those leading to differentiated integration.
EU member states are also well-known to be, on occasion, guilty of non-compliance (Börzel, 2021). Whereas this is a quiet form of seeking to escape from very specific aspects of European integration (e.g., the transposition of individual directives), we see disintegration as a louder and more activist form.
This thematic issue on the causes and modes of European disintegration explores a different angle by focusing on the causes and modes of European disintegration beyond Brexit. It seeks to provide answers to two main questions. First, what are the drivers of potential European disintegration across countries? The increased attention on the costs of uniform EU policies plays out differently in different EU member states, each with substantially different policy preferences. Second, what are the actual and potential modes of European disintegration beyond a full-blown exit from the EU? Disintegration drivers have led and might lead to different outcomes.
This thematic issue innovates not only due to the questions it raises but also by deploying a multidisciplinary social science perspective. The contributions include quantitative, qualitative, and theoretical work. The empirical contributions zoom in on multiple countries, including Austria, Italy, France, Germany, Greece, and the UK.

The Causes of European Disintegration
The contributions to the causes of EU disintegration go beyond the immediate causes of Brexit. The extensively studied proximate causes of Brexit may be different from more long-term drivers in the UK and other member states. The first set of articles critically reviews these drivers. Crombez et al. (2023) present a theoretical model on the role of preferences of politicians and voters as potential causes of (dis)integration. Ruiz et al. (2023) look at the 2005 referendum in France on the proposed EU constitution and find long-lasting effects. Looking at two other member states, Greece and Italy, Kouloglou and Georgarakis (2023) find consistent evidence that both cultural and economic factors play a role in public support for the EU and its institutions. Donat and Lenhart (2023) look not only at different causes (attitudes and approaches to EU integration) but also an understudied group, namely regional members of parliament, which sit between voters and national and EU-level political elites.

The Modes of European Disintegration
The second question focuses on the modes of disintegration and raises a point that has been largely overlooked in the extant literature. The proposed contributions on the modes of disintegration go beyond the growing literature on differentiated integration and non-compliance. These contributions critically address how pressures towards EU disintegration are translated into certain modes and preferences for disintegration. Brexit can hence be understood as only one specific mode of disintegration.
O'Dubhghaill and Van Kerckhoven (2023) analyze the special case of Gibraltar, a UK enclave in Spain, and demonstrate the risk of Brexit resulting in patchwork disintegration across different parts of the UK. Furst (2023) analyzes how temporary internal border controls in the Schengen area lead to temporary disintegration in terms of free movement. Relatedly, Josipovic et al. (2023) discuss sectoral disintegration through the case of Austria's contestation of the Common European Asylum System and opposition against the expansion of the Schengen area to Romania and Bulgaria.

Conclusion
This thematic issue addresses two different but interlinked questions: What drives EU disintegration? And what are the potential modes of EU disintegration? The rationale for combining these two perspectives is obvious but has not yet been discussed extensively in the literature: Different causes of EU disintegration pressures may drive different potential outcomes.
Taken together, the contributions advance scholarly understanding of European (dis)integration and produce timely, and policy-relevant, insights on how to identify (and perhaps counter) drivers of disintegration across Europe. In addition, outlining different modes of disintegration that can respond to these drivers without resulting in a complete withdrawal from the project of European integration.