Advocates of the European Union (EU) aspire to a United States of Europe, a political union with its own character and voice, but unified peacefully and democratically along the lines of the United States of America. A long line of elites have invoked the Philadelphia Convention and announced ambitions of matching American strength and unity. Then-President of France Jacques Chirac urged, "The European Union itself [must] become a major pole of international equilibrium, endowing itself with the instruments of a true power." Similar statements from others could be multiplied tediously. These sentiments are not confined to elites; an impressive majority of European citizens want the EU to be a peer competitor of the United States. (1)
But what would it take to make a political union, a major pole, out of Europe? The received wisdom is ever-closer union, a gradual process of trial-and-error economic and administrative cooperation, where success is neither continuous nor automatic yet is nevertheless occurring--and at a respectable clip too. Analysts at the Central Intelligence Agency predict that Europe will unite by 2015, and Charles Kupchan makes the case that European integration is faring well, relatively speaking, and Europe faces problems the United States faced at the end of the nineteenth century. (2)
The empirical puzzle of European unification depends on one's perspective. For some, voluntary unions should never happen. States value their autonomy superlatively and would never give it up to a state that could not conquer them. And yet, the American colonies did just that--why not the EU as well? For others, voluntary unions should happen more commonly. Classic determinants of integration, like trade and communication, are as strong as they have ever been. Nonetheless, voluntary unification is rare, and European integration seems to be hitting a glass ceiling.
What does the American past tell us of the European future? The importance of the answer could hardly be higher. How integrated Europe grows in the coming years will affect the deepest contours of great-power politics for generations. Even skeptics of the EU concede that, unified, the European continent would be a juggernaut. However, scholars and policymakers have a limited understanding of how and why states voluntarily unify.
I argue that the model of ever-closer union is flawed. The United States is a helpful historical idol for Europe, but the case challenges cherished views on all sides. The conventional wisdom on ever-closer union relies on three logics: union may proceed through states binding themselves to prevent internal violence, through converging economic preferences, and through increased contact and communication, which foster common identity. Yet none of these logics were strong in America's founding. Instead, America's voluntary political union happened when states formed an extreme balancing coalition against offshore powers. Ultimately I find that the barriers to union are higher in Europe today than when the United States united, though that may not last.
To develop the argument, I first lay down the groundwork, defining concepts, setting benchmarks for political integration, and determining the scope of the analysis....