Showing Ideas as Causes:The Origins of the European Union Craig Parsons Why does Western Europe,with its quasi-federal European Union (EU),have international institutions that are so much more developed than those in other regions?Scholars give two main answers.For"structuralists"like Andrew Morav- csik and Alan Milward,the EU responded to objective structural imperatives. International interdependence was particularly acute in postwar Europe,so govern- ments built particularly strong institutions to meet policy challenges.For "institu- tionalists"in the tradition of Ernst Haas,structural imperatives may have driven initial postwar institution building,but subsequent steps were heavily path-depen- dent.Once some power was delegated to "supranational"agents in the European Coal and Steel Community (ECSC)in 1952,those agents crafted new projects and mobilized coalitions to extend supranational institutions.From this"spillover"arose the broader European Economic Community(EEC)in 1958-the direct foundation of today's EU-and its later development.2 Although I accept insights from both approaches,I argue that neither explains why Europeans chose this"community"Europe over radically different alternatives in the 1950s.If postwar structural conditions generated widely perceived impera- tives to European cooperation,they did not dictate its shape or extent.If institutional path-dependence helped"lock in"the contested EEC institutions after 1958,it did not push Europeans in any specific direction before then.Within vague structural and institutional pressures,only certain ideas led Europeans to the EEC rather than to less extensive cooperation in much weaker international institutions(or without For comments I thank Chris Ansell,Neil Fligstein.Nicolas Jabko,Elizabeth Kier,Andrew Moravcsik, Paul Pitman,Wayne Sandholtz,Robert Rauchhaus.Jeffrey Vanke,Steve Weber,two anonymous reviewers and the editors of International Organization,and audiences at the University of British Columbia,the University of Califomia at Berkeley,Harvard University,the Georgia Institute of Technology,and Syracuse University.For research support I thank the National Science Foundation,the MacArthur Foundation,and the Institute on Global Conflict and Cooperation. 1.See Moravcsik 1998;and Milward 1992. 2.See Haas 1958:and Sandholtz and Stone Sweet 1998. International Organization 56,1.Winter 2002.pp.47-84 2002 by The IO Foundation and the Massachusetts Institute of TechnologyShowing Ideas as Causes: The Origins of the European Union Craig Parsons Why does Western Europe, with its quasi-federal European Union (EU), have international institutions that are so much more developed than those in other regions? Scholars give two main answers. For “structuralists” like Andrew Morav￾csik and Alan Milward, the EU responded to objective structural imperatives.1 International interdependence was particularly acute in postwar Europe, so govern￾ments built particularly strong institutions to meet policy challenges. For “institu￾tionalists” in the tradition of Ernst Haas, structural imperatives may have driven initial postwar institution building, but subsequent steps were heavily path-depen￾dent. Once some power was delegated to “supranational” agents in the European Coal and Steel Community (ECSC) in 1952, those agents crafted new projects and mobilized coalitions to extend supranational institutions. From this “spillover” arose the broader European Economic Community (EEC) in 1958—the direct foundation of today’s EU—and its later development.2 Although I accept insights from both approaches, I argue that neither explains why Europeans chose this “community” Europe over radically different alternatives in the 1950s. If postwar structural conditions generated widely perceived impera￾tives to European cooperation, they did not dictate its shape or extent. If institutional path-dependence helped “lock in” the contested EEC institutions after 1958, it did not push Europeans in any specific direction before then. Within vague structural and institutional pressures, only certain ideas led Europeans to the EEC rather than to less extensive cooperation in much weaker international institutions (or without For comments I thank Chris Ansell, Neil Fligstein, Nicolas Jabko, Elizabeth Kier, Andrew Moravcsik, Paul Pitman, Wayne Sandholtz, Robert Rauchhaus, Jeffrey Vanke, Steve Weber, two anonymous reviewers and the editors of International Organization, and audiences at the University of British Columbia, the University of California at Berkeley, Harvard University, the Georgia Institute of Technology, and Syracuse University. For research support I thank the National Science Foundation, the MacArthur Foundation, and the Institute on Global Conflict and Cooperation. 1. See Moravcsik 1998; and Milward 1992. 2. See Haas 1958; and Sandholtz and Stone Sweet 1998. International Organization 56, 1, Winter 2002, pp. 47–84 © 2002 by The IO Foundation and the Massachusetts Institute of Technology