Does bilateralism foster co-operation in Europe?

Europe is oscillating between increased integration and permanent risk of dissolution. In this framework, one often debates the role of bilateral relations, with the following question: does bilateralism foster or delay overall co-operation? We address this question in an experimental framework where we study the behaviour of agents who are confronted with a multiplicity of prisoners' dilemma games, either in a bilateral or a multilateral way. We surprisingly observe that the co-operation between all is significantly higher when interactions are bilateral and that the difference between these two institutional contexts is growing in time in favour of bilateralism. Reprinted by permission of Blackwell Publishers