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Theories of European Integration

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Many theories have emerged which attempt to explain the process and outcome of integration in Europe. They try to clarify how and why the European Union came about and how it is today. Theories are important as they help us to understand how the EU works, and having a better understanding of how the EU has developed allows us to hypothesise about what the EU might be like in the future. It is also important to be familiar with the different approaches people take when explaining European integration, as whatever is written is always grounded in a particular set of assumptions which should be taken into account when reflecting on what has been said. The following are some of the most dominant theories of European integration.


Neo-functionalism was a popular theory of European integration in the 1950s and 1960s. The most prominent neo-functionalist writer was Ernst Haas in his book ‘The Uniting of Europe’ in 1958. The important question that neo-functionalists attempt to ask is: how does cooperation in specific economic policy sectors lead to greater economic integration in Europe and then to wider political integration? The question is answered with the concept of spillover, which takes two forms. Firstly, functional spillover is used to explain the way in which integration in one policy area, for example coal and steel, creates pressure for integration in further areas, such as currency exchange rates. Secondly, political spillover is used to explain the importance ofsupranational and subnational actors in the integration process, as they create further pressure for more integration to pursue their interests. Pressure groups and political parties are also considered to be important actors. As a result of these processes of spillover, neo-functionalists see European integration as a self-sustaining process which will culminate in the creation of a new polity with its centre in Brussels.


Intergovernmentalism emphasises the role of the nation state in integration, and argues that the nation state is not becoming obsolete due to European integration. Alan Milward, an intergovernmentalist writer, argued that the national governments of the member states were the primary actors in the process of European integration, and rather than being weakened by it as some of their sovereignty was delegated to the EU, they became strengthened by the process. This is because in some policy areas it is in the member states’ interest to pool sovereignty. Intergovernmentalists argue that they are able to explain periods of radical change in the EU as when the interests of the member states governments converge and they have shared goals, and periods of slower integration as when the governments’ preferences diverge and they cannot agree. They continually emphasise the role of national governments and the bargaining between them in the integration process.

Liberal Intergovernmentalism

Liberal intergovernmentalism is a development on the intergovernmental theory of European integration, established by Andrew Moravcsik in his 1998 book ‘The Choice for Europe’. In the 1990s it was the dominant theory of European integration. Like intergovernmentalism, liberal intergovernmentalism emphasises national governments as the key actors in the process of integration. However, it also incorporates the liberal model of preference formation, whereby national governments have a strong idea of what their preferences are and pursue them in bargaining with other member states. Liberal intergovernmentalists argue that the bargaining power of member states is important in the pursuit of integration, and package deals and side payments also occur in the process of making deals. They see institutions as a means of creating credible commitments for member governments, that is, as a way of making sure that other governments that they make deals with will stick to their side of the bargain. Liberal intergovernmentalists consider supranational institutions to be of limited importance in the integration process, in contrast to neo-functionalists.

(New) Institutionalism

Institutionalism emphasises the importance of institutions in the process of European integration. New institutionalism developed over the course of the 1980s and 1990s to explain behaviour in the United States Congress, but has since been used to explain European integration. New institutionalism has three key strands: rational choice, sociological and historical.

Rational choice institutionalism emphasises the way in which actors pursue their individual preferences within the context of institutional rules. Rational choice institutionalists are interested in the way in which the preferences of actors in the integration process change as a result of changes in the institutional rules. An example of an institutional rule that constrains actors’ behaviour is the ordinary legislative procedure, which affects how European actors can pursue their preferred policy outcomes. It is a close relative of liberal intergovernmentalism.

Sociological institutionalism sees institutions in a slightly different way, emphasising broader norms and general rules and the way in which these shape the identities and preferences of actors in the integration process. Sociological institutionalists also pay particular attention to the culture of institutions and the socialisation of actors within them, and consider the patterns of communication and persuasion that occur during policy making and in the pursuit of integration.

Historical institutionalism focuses on the effect of institutions over time, and how institutions can go on to constrain the actions of the actors who designed them. A key feature of historical institutionalism is path dependency, whereby decisions made about institutions in the past impact significantly on the outcomes of the future and are difficult to reverse. In 1996 Paul Pierson wrote specifically about path dependence in the EU, and emphasised the assumption that actors are not fully aware of what the consequences of their decisions at a particular point in time will be for their future action, and that their future behaviour is likely to be constrained by past choices.

Multi-level Governance

Multi-level governance (MLG) is a much newer theory of European integration. MLG argues that policy making and integration in the EU is much too complicated to be explained by static integration theories. Key writers Liesbet Hooghe and Gary Marks defined MLG as the dispersion of authority across multiple levels of politicalgovernance. That is, they argue that over the last fifty years, authority and sovereignty has moved away from national governments in Europe, not just to the supranational level with the EU, but also to subnational levels such as regional assemblies and local authorities. They see policy making in the EU as uneven and frequently changing, and as such they highlight the limitations of other theories of European integration which disregard the significant numbers of different actors from all of the different levels of governance in Europe.

Technical Terms

Spillover: an unexpected consequence of the spreading of cooperation from one area to another.

Supranational: power or influence at a level above or beyond the boundaries of the nation state.

Polity: a politically organised unit.


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