Theories of European Integration

Author: Paul C. Saunders, February 2020.

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“…although the failure of the Euro challenges the EU’s future, there is no reason to believe that the EU, even without the United Kingdom, will disappear anytime soon. In this article, I will briefly review the history of European integration and argue that existing theories of integration, while helpful, do not fully explain the phenomenon and that new intergovernmentalism remains a work in progress.”

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A new theory of European integration has recently emerged. This theory, proposed for further study by Professors Christopher Bickerton of Queens College, Cambridge, Dermot Hodson of the University of London and Uwe Puetter of Central European University, argues that the institutional supranationalism of the European Union has been replaced by ad hoc cooperation among state leaders with relatively no involvement from the institutions. The scholars call this “new intergovernmentalism” and argue that it is a “distinct phase of European integration.” (Bickerton et al). The long-term implication of this theory is that over time, the supranational, institutional superstructure of the European Union (EU) will be replaced by informal groups of government leaders who are reaching agreements among themselves, based on what they perceive to be their national interests, without the supervision of the supranational institutions or the consent of their citizens. This will be discussed and challenged below in the context of other theories of European integration.

At the heart of the argument between those urging “an ever closer union” and those who oppose it, is the tension between state sovereignty (or nationalism) and supranational institutions that should be able to deliver what the individual states themselves cannot. Some were willing to sacrifice some state sovereignty only if it is necessary to do so and others believed that an “ever closer union” with diminished state sovereignty would not only replicate the fully-integrated United States but would lead to an economic juggernaut. That has not happened and although the failure of the Euro challenges the EU’s future, there is no reason to believe that the EU, even without the United Kingdom, will disappear anytime soon. In this article, I will briefly review the history of European integration and argue that existing theories of integration, while helpful, do not fully explain the phenomenon and that new intergovernmentalism remains a work in progress.

The History of European Integration

It is difficult and likely futile to try to identify the origins of the impetus toward integration for Europe. Roman emperors dreamed of a Pax Romana and St. Thomas More dreamed of worldwide peace under the leadership of the Pope. As early as the Crusades beginning in the Ninth Century, when Europe was defined by regions as opposed to states as defined in the Westphalian system, Crusaders came together from many different regions (Tyerman 93). For example, the first wave of the march toward Constantinople, led by Peter the Hermit in 1096, included Crusaders from lands between the Rhine and the Atlantic, the English Channel and the Mediterranean. Other participants came from Denmark to Apulia, and from England to Austria. After Constantinople fell a second time to forces led by Mehmed II in 1453, in a siege in which thousands of Italians and Greeks were killed, there were calls for the creation of a union of European nations against the Turks. The calls came in 1453 from George of Podĕbrady, the King of Bohemia. His goal was to create a union between European kingdoms and monarchs in order to maintain peace, establish international rule of law and non-interference by one state in the affairs of another. His proposals were not well- received and “never saw the light of day” (Eisenchteter).

More concrete proposals for European integration came when the Congress of Vienna was created in 1814 by Austria, Russia, Prussia and Great Britain to fashion a post-Napoleonic Europe. When Napoleon was defeated at Waterloo in Belgium, France, Sweden, Portugal and Spain also joined the Congress. On the eve of the first meeting of the Congress, an important pamphlet, prepared specifically for the Congress by French social theorist Henri de Saint-Simon entitled, De la réorganization de la société européenne, called for a complete reorganization of the political systems of Europe:

“The end goal of the reorganization process would be a European Confederation, ruled by a European Parliament . . . Europe could only be truly united if an institutional structure was created which expressed ‘the general interest’ of the European peoples” (Swedberg 154).

We do not know whether or to what extent the participants of the Congress took note of Saint-Simon’s pamphlet, although a copy was given to each participant. We do know that the Congress essentially redrew the map of Europe and stipulated that the boundaries could not be redrawn without the consent of the eight member-countries. There was no mention of creating a European Union.

The issue of European integration came up in 1831, when Polish political theorist Wojciech Bogumil Jastrezębowski wrote his Treatise on Eternal Alliance among Civilized Nations: The Constitution for Europe. That treatise provided that “all nations belonging to the eternal alliance in Europe should be equally subject to European laws” and that “the existence, independence and property of each nation will be a subject of the particular protection of European laws” (Bunikowski). Jastrezębowski was prescient. Although not to the extent that he anticipated, the European Union later subjected citizens of the Union to the protection of many European laws.

Following the Congress of Vienna, the Concert of Europe, part of the Vienna System or the Congress System and largely controlled by Prussia, Russia, Great Britain, Austria and France, led to a long peace that lasted until the revolutions of 1848. At the Paris Peace Conference held in August 1849, the French writer Victor Hugo floated the idea, sometimes called “the Great Idea” of a United States of Europe (Metzidakis 72-84). Hugo believed that liberty was determined by free trade and that protectionism and colonialism were its enemies. Free trade, he believed, required the elimination of state frontiers and that only a United States of Europe could bring that about.

During the long peace that followed the Concert of Europe from 1815 until 1848 and again from 1870 to 1914, Europe was characterized by alliances between and among otherwise sovereign states. The Triple Entente (Russia, France and Great Britain) and the Triple Alliance (Germany, Austria-Hungary and Italy) are two such examples. Those alliances are sometimes called “special cases” or “single-use” examples of integration to balance against other great powers whose intentions were difficult to ascertain. Unfortunately, because those alliances led to poorly-understood military mobilizations that escalated tensions, they almost certainly led to World War I (Leonhard 89-110).

The conclusion to be drawn from this brief history is twofold. First, the notion of territorial state sovereignty ostensibly created in the Peace of Westphalia did not actually define Europe, at least not until the post-World War II period. The continent consisted of states whose boundaries and national identities were constantly in flux. The 1918 Treaty of Versailles that ended World War I redrew the European boundaries—and those of the Middle East and elsewhere—yet again. By that time, not a single European country had the same boundaries that it had prior to the Congress of Vienna. Therefore, the notion of state sovereignty that is at the heart of Brexit and the notion of national identity based on language, culture or religion that is at the heart of Euroskepticism today are of relatively recent vintage. The second conclusion is that the idea of European integration is not as new as the idea of state sovereignty.

Theoretical Bases of European Integration

Why do independent states that cherish their sovereignty choose to align themselves with other states to integrate their economies, commerce and governance? Under what circumstances would a sovereign state choose to cede any part of its sovereignty to an un-elected body over which it has no control or at best shared control? The answer to those questions, at least as they concern the present day, lies in the international nature of today’s world economy and the technological advances that drive modern civilizations. The local links of the past between producers and consumers no longer exist; labor and goods are mobile and extraterritorial. Today, states must become involved in international organizations, such as the United Nations and the World Trade Organization, to maximize their power. Doing so is not a surrender of sovereignty in the Westphalian sense; rather, it is a recognition that state power is not diminished by such participation but is enhanced by it. In this sense, the whole is greater than the sum of its parts. This is the fundamental economic and political raison d’être of European integration today.

Integration theory attempts to answer two questions: why should nation-states integrate and if they do, who is in charge? Such a theory should be able to explain what has already been observed and to suggest plausible scenarios for what is likely to happen in the future. The theoretical basis for nation-state integration has been widely discussed by political scientists often with diametrically opposed constructs. Of the many theories that have been advanced, including realism, neo-liberalism and constructivism, as explained below I have chosen five theories for more in-depth discussion: neo-functionalism, post-functionalism, intergovernmentalism, balance of power and new intergovernmentalism. As we shall see, no single theory satisfactorily explains the progenitors of European integration or how it came about when it did, but each is useful in its way to understand European integration as it has evolved since the end of World War II. Unfortunately, none suggests plausible scenarios for the future.

Functionalism and Neo-functionalism

Functionalism was a prominent theory in the period before the creation of European institutions and is based on the work of David Mitrany and John Maynard Keynes. They believed that when serious issues arose such as the Normandy invasion or serious market failures that could not successfully be addressed by one country alone, they could instead be addressed by supranational organizations. One of the many examples of functionalism is international air traffic control, which is necessary for international air travel and which no single country can undertake alone. Functionalism results from a belief that if national institutions are not able to deal satisfactorily with the challenges they face, an international institution might be able to do so. If so, states will cooperatively transfer some of their sovereign power to the international institution for the greater good. As these international agencies grow in competence, a spillover effect expands their mandates and competencies so that, in time, they become normative and have enforcement powers.

The modern father of functionalism was Jean Monnet. When he created the European Coal and Steel Community, he assigned specific and relatively narrow “functions” to the Community, fully expecting that the integration that they represented would eventually “spill over” to other areas and that more integration would follow. Monnet believed that Europe would ultimately unite not merely as an economic union but as a political one as well. In 1962, he wrote “The necessary precondition of a partnership between America and Europe is that Europe should be united and thus be able to deploy resources on the same scale as America….The creation of a united Europe brings this nearer by making it possible for America and Europe to act as partners on an equal footing…” (Monnet).

The United Nations (UN) is an example of functionalism at work. When the UN was first created, the primary goal was to create an international system based on territorial state sovereignty (see Article 2 of the UN Charter) that would prevent a repeat of World War II. Over time, as the UN agencies grew, their mandates grew as well and they became populated by employees known as the “elites” who were administrators with dual loyalties to their own countries and the supranational institutions (Puchala, “World Hegemony” 571, 576).

Functionalists believed that in the short term, it is possible to separate the technical competencies of international organizations from political questions but in the longer term, the spillover effect would lead to a union, with individual sovereignties disappearing. Monnet’s colleague George Ball described this spillover effect as a chain reaction:

“All of us working with Jean Monnet well understood how irrational it was to carve a limited economic sector out of the jurisdiction of national governments and subject that sector to the sovereign control of supranational institutions…. Monnet recognized that the very irrationality of this scheme might provide the pressure to achieve exactly what he wanted—the triggering of a chain reaction” (Spolaore).

In approximately 1958, functionalism evolved into neo-functionalism, a theory developed by political scientist Ernst Hass among others. In 1958, Haas wrote in The Uniting of Europe that “[T]he process of community formation is dominated by nationally constituted groups with specific interests and aims, willing and able to adjust their aspirations by turning to supranational means when this course appears profitable.” (148). Essentially, neo-functionalism contended that when integration took place, unexpected beneficial and self-reinforcing results might occur, such as the creation of groups that might encourage more integration. This would ultimately lead to supranational authorities whose “political entrepreneurship” would promote further integration (Moravcsik). Haas explained, “Once established, the central institution will affect political integration meaningfully only if it is willing to follow policies giving rise to expectation and demands for more—or fewer—federal measures. In either case, the groups concerned [i.e. nation-states] will organize across national state boundaries in order to be able to influence policy” (Haas 147). In other words, integration begets more integration.

Specifically, neo-functionalists “conceptualized the state as an arena in which societal actors operate to realize their interests” (Hooge & Marks 1117). The translation of that rather opaque description might be that every actor looks out for itself, which appears to be a classic realist notion. Neo-functionalism recognizes that international cooperation, at first intended only to relate to technical issues, could evolve to address political issues as well. Although functionalism and neo-functionalism theories influenced Monnet and led to the creation of the European Coal and Steel Community and the Maastricht Treaty, Haas became disillusioned with his own theory.

In 1976, he declared that functionalism was “obsolescent” as a theory of integration, in large part because the inevitable move toward a supranational integration in Europe was not actually occurring (Haas “Turbulent Fields”). Donald Puchala, a Professor at the University of South Carolina, wrote in 1971 that European integration was like the famous three blind men who encounter an elephant: the observers were focusing too much on what should be occurring, not seeing what was actually happening. Of course, Puchala’s blind men were each “seeing” only a part of the elephant not the whole animal (Puchala “Of Blind Men”). In Europe, what was “actually happening” was that the member-states of the fledgling European community, led primarily by France, had an excellent view of the whole Community but were uncomfortable with the supranational structure that the Community was creating. A good example of this was the so-called “Empty Chair Crisis” of 1963. France’s President Charles de Gaulle opposed efforts to limit the veto power of the members of the European Council and in retaliation recalled his representative in Brussels, announcing that France would no longer participate in the Community’s specialized committees. The crisis was resolved by the so-called Luxembourg Compromise in which France reserved the right to cast a veto “when very important issues are at stake” without a clear agreement as to what those were. The point is that, as Haas observed, supranational integration was unpopular to many.

Neo-functionalism has several flaws as a theory of integration. Among them is the fact that it cannot be empirically shown that supranational agencies would grow in competence and mandate, encroaching without permission on the state sovereignty of their constituent states. As Andrew Moravcsik wrote in The Choice for Europe, “At one level, the failure of neo-functionalism was empirical. European integration had not expanded steadily but by stops and starts…. Neo-functionalism proved at once too ambitious, too vague, and too incoherent to generate precise predictions suitable for empirical evaluation” (Moravcsik 14).

Functionalism and neo-functionalism, if they were valid theories, would necessarily lead to a dichotomy. If integration were to cause increased integration until there was a union with no more national sovereignties, the nation-states could decide that they did not want such a union and the experiment would be over. Or, they could decide that the inevitable union was what they wanted and they would move quickly to bring it about. Since neither situation has occurred in Europe, these two theories of European integration have fallen into disfavor.


Professors Liesbet Hooghe and Gary Marks have recently described a new theory of integration, which they call “post-functionalism.” According to this theory, integration is “a conflictual process arising from incompatible belief systems. It is a form of jurisdictional restructuring that, like the development of the nation-state, has produced a profound cultural divide” (Hooghe & Marks 1117). For example, they argue that the decision in the United Kingdom to hold a referendum on Brexit “illustrates a tension between functionalist pressures for integration and national resistance that is part of a wider divide across Europe” (1123). To them, post-functionalism more accurately describes the current illiberalism that we see in Europe, especially in places like Hungary in 2010 and Poland in 2017. Such illiberalism “suggests that transnational actors can make the greatest difference when they can leverage domestic opposition” as they did in the United Kingdom Brexit vote, Poland, Hungary and, one might add, the United States (1128). In other words, choosing whether to integrate or not becomes a political, rather than an economic, decision.

The term “post-functionalism” suggests a relationship between that and functionalism that may not in fact exist. “Post-functionalism” as described by Professors Hooghe and Marks is merely a description of the political activism that occurs when people who had been agnostic about a European Union of any sort become activists when they learn that the unelected supranational elites were taking actions that adversely affected them. It is largely unrelated to the spillover effect that functionalism predicts and rather describes a normal reaction by citizens when governmental actions adversely affect them.


As one of its proponents, Andrew Moravcsik, a prominent Professor of Politics at Princeton University who developed the theory of liberal intergovernmentalism, has written, intergovernmentalism suggests that states fundamentally wish to retain their sovereignty and will join forces only when it is in their interest to do so without regard to what the supranational elites believe they should do. This theory describes negotiation and bargaining between and among nation-states whose relative power is “shaped above all by asymmetrical interdependence, which relates to the relative value of agreement to different governments” (Moravcsik 7). According to intergovernmentalism, governments that will benefit the most from an agreement with other governments (as opposed to benefiting from unilateral action) will make greater compromises with one another.  In other words, they act together when it is in their best interest to do so. Accordingly, Moravcsik’s intergovernmentalism is a form of realism in which states pool their resources, usually, if not entirely, economic resources, only when it serves their interests to do so. With the culmination of Brexit, there is a powerful argument that intergovernmentalism not only explains the past but suggests plausible scenarios for the future.

Balance of Power

In 2011, Professor Sebastian Rosato of the University of Notre Dame and a former student of the realist Professor Stephen Walt while at the University of Chicago, tried to explain European integration in terms of the traditional realist notion of “balancing”. Rosato asserts that countries engage in integration when they believe that they are not as strong militarily as some of their rivals and do not know their intentions. He argues that in light of the collapse of the Soviet Union, the balance of power that resulted from European integration is unlikely to result in any further steps toward integration so long as that balance of power is maintained. This classic balancing theory was first articulated by Professor Kenneth Waltz in Theory of International Politics and more recently refined by Professor John Mearsheimer in The Tragedy of Great Power Politics. In sum, the theory posits that the integration that one sees in the EU was neither the result of the economic conditions that existed in Europe after World War II nor of the latent desire to recreate the Concert of Europe. It was not even a result of trying, in the words of NATO’s first Secretary General Lord Hastings “Pug” Ismay, to “keep the Americans in, the Russians out and the Germans down” since the Germans were already defeated (Lindley-French 37). Rather, according to Rosato, the real purpose of European integration was to “balance” against the Soviet Union. With the breakup of the Soviet Union that began in 1989, the end of the European integration project was in sight: “Just as the emergence of the Soviet Union as the only great power on the continent that pushed the Europeans to make the EC, its collapse removed the incentive for integration” (Rosato 85).

Rosato’s hypothesis generated a great deal of criticism and debate (“Correspondence”). It can be argued that there are many other reasons why sovereign states would wish to integrate in general and in Europe in particular other than balancing. The balance of power theory is the least likely of the explanations for European integration because NATO was created for the express purpose, as noted above, “of keeping the Russians out” (Lindey-French). Since the EU and its predecessors never established the common defense community that was envisioned at the beginning of European integration, Rosato’s balancing hypothesis appears to be an after-the-fact conjecture that the real purpose for the creation of the EU was to defend the European countries against the aggression of the Soviet Union, even though there is little to no evidence for that hypothesis. In fact, there is considerable evidence against it, NATO itself being Exhibit A.

New Intergovernmentalism

As noted above, Professors Bickerton, Hodson and Puetter have recently attempted to use the theory of new intergovernmentalism to explain the paradox of the relative success of the European experiment, despite the stagnation of supranational institutions created by various treaties. None of the existing theories of integration explains that paradox. This new theory attempts to do so, arguing that political leaders of member-states decided to cooperate and to create new, ad hoc, often single-issue bodies outside the traditional supranational institutions rather than to increase the power of those institutions. New intergovernmentalism challenges the theories of integration, especially neo-functionalism, which argues that competencies will be transferred from national capitals to those institutions, and the balance of power theory, which posits that integration will be driven largely, if not entirely, by a desire for increased security.

Under new intergovernmentalism, there is an increase in “intergovernmental cooperation rather than delegation to supranational institutions” (Bickerton et al 703) that might explain the paradox; it is the ad hoc cooperation rather than the supranational institution that might explain the paradox; it is the ad hoc cooperation rather than the supranational institutions that explains the success of the European experiment. Bickerton and his colleagues point to the end of the so-called “permissive consensus” that resulted in a crisis in national representative politics and drove national leaders to cooperate rather than seeking guidance from their citizens. That cooperation, in turn, resulted in the creation of new bodies outside the supranational institutional framework, such as the European Financial Stability Facility, which was explicitly created to give financial support to troubled member-states. Their success, rather than the success of the supranational framework, accounts for the success of the EU.

This theory is not without criticism. Writing in the Journal of Common Market Studies, Professor Frank Schimmelfennig argues that rather than representing a new theory, new intergovernmentalism is better understood as a “phase-specific approach” focusing on a particular set of policies and that the features of the new governmentalism do not define either the post-Maastricht era in general nor do they “neatly coincide with the pre-/post Maastricht temporal divide” (Schimmelfennig 724). In other words, he argues that what Bickerton and colleagues see is nothing more than a “one off” set of phenomena that do not call into question the overall success of the structure of the EU. Such criticism may explain why Bickerton and his colleagues described the post-Maastricht period as a “paradox” and why they put forth their proposal for “further study” rather than as a fully formed theory.


Theories of international or regional integration do not necessarily deliver what they promise. As noted, a theory of integration is useful if it can be used to explain behavior that has been observed or to suggest plausible scenarios for the future. There is no evidence that any of the current theories of integration does both and most do neither. Nation-states today are members of a modern world in which membership in international organizations may erode their sovereignty but is seen as a necessary step for the greater good. Integration is not merely an aspiration; it is a fact of life around the world. International norms such as the Geneva Conventions and the Convention on the Prevention and Punishment of the Crime of Genocide limit the freedom that leaders of sovereign states previously enjoyed to do whatever they wished within their territories, but again, these limitations promote a greater good. Today, state power requires participation in the world economy and its international structure. That reality drives integration.

Hooghe and Marks (and probably Rosato, Moravcsik, Bickerton and his colleagues as well) agree that no single theory of European integration fully explains the actual history and evolution of the EU into its modern form but that they all “provide a line of sight into European integration…from contrasting perspectives, using different bodies of evidence to shed light on distinct puzzles” (Hooghe & Marks 16). I would go further. As noted above, a robust theory of European integration ought at least to be able to explain past events and to suggest plausible future scenarios. None of the theories discussed in this article meets those requirements although each suggests ways of understanding the consequences of future events. That is not sufficient. As Professor Michael Oppenheimer of NYU’s Center for Global Affairs has written in Pivotal Countries/Alternate Futures: Using Scenarios to Manage American Strategy, “The principal objective of alternate futures is to improve observation of a rapidly changing and complex reality, and to encourage early recognition of and reaction to emerging trends that may shift the ground under current policies” (94). The same is true of integration theories. If they meet Oppenheimer’s criteria of plausibility, distinctiveness (i.e. different from other theories) and consequence (the theories must be useful), they deserve our attention and should lead to a better understanding of what is happening in Europe today and in the days and years to come.

Works Cited

Bickerton, Christopher, Hodson, Dermot & Puetter, Uwe, “The New Intergovernmentalism: European Integration in the Post-Maastricht Era,” Journal of Common Market Studies, Vol. 53, No. 4, 2015, pp. 703-722.

Bunikowski, Dawid, “From Jastrzębowski’s idea of integrated Europe (the treaty (sic) of 3 May 1831) to the April Constitution of 1935,” Conference Paper, Ronin Institute, April 2016.

“Correspondence: Debating the Sources and Prospects of European Integration,” International Security, Vol. 37, No 1, 2012, pp. 178-199.

Lindley-French, Julian, The North Atlantic Treaty Organization: The Enduring Alliance, Routledge 2015, p. 37.

Eisenchteter, Jules, ”A European visionary in XVth century Bohemia?” Kafadesk, March 6, 2018.

Haas, Ernst, “Turbulent Fields and the Theory of Regional Integration” International Organization, Spring 1976, pp. 173-212.

Haas, Ernst, “The Uniting of Europe,” The European Union: readings on the theory and practice of European integration, Reinner 2014 pp. 145-149.

Moravcsik, Andrew, The Choice for European Union: Social Purpose and State Power from Messina to Maastricht, Cornell University Press 1998, p. 13.

Hooghe, Liesbet & Marks, Gary, “Grand theories of European integration in the twenty-first century,” J. European Public Policy, January 17, 2019, passim.

Metzidakis, Stamos, “Victor Hugo and the Idea of the United States of Europe,” Nineteenth Century French Studies, , Vol. 23, No. 1/2, Fall-Winter 1994-95, pp. 72-84.

Monnet, Jean, “A Ferment of Change,” Journal of Common Market Studies, Vol. 1, No. 1, 1962, pp. 203-211.

Oppenheimer, Michael, Pivotal Countries, Alternate Futures: Using Scenarios to Manage American Strategy, Oxford University Press 2016, p. 94.

Spolaore, Enrico, “What is European Integration Really About? A Political Guide for Economists,” in The European Union: readings on the theory and practice of European integration, Nelson, Brent & Stubb, Alexander, Rienner 2014, p. 374.

Puchala, Donald, “Of Blind Men, Elephants and International Integration,” Journal of Common Market Studies, Vol. 10, No. 3, March 1972, p. 267.

Schimmelfennig, Frank, “What’s the New News in ‘New Intergovernmentalism: A Critique of Bickerton, Hodson and Puetter,” Journal of Common Market Studies, Vol. 53, No. 4 2015, pp. 723-730.

Swedberg, Richard, “Saint-Simon’s Vision of a United Europe,” European Journal of Sociology, Vol. 35, No. 1 1994, p. 154.

Rosato, Sebastian, “Europe’s Troubles: Power Politics and the State of the European Project,” International Security, Vol. 35, No. 4 2011, p. 85.

Tyerman, Christopher, God’s War: A New History of the Crusades, Belknap-Harvard 2006, p. 93.

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