Abstract: "While the ubiquity of communication in European, and international, governance may be empirically observed, its relevance for collective decision processes is still subject to dispute. The question is whether communication constitutes a factor influencing outcomes separately from other important explanatory factors like established interests (preferences) and power. On this issue, a new line of conflict has developed in recent years (e.g. Eriksen/Weigard 1997, Risse 2000) along the firmly established divide between rationalists and constructivists (Keohane 1988, Lapid 1989). For rationalists, communication plays an inferior role compared to other explanatory factors. Empirically observed communication among actors is frequently treated as unimportant 'noise'. After all, coordination, even cooperation in Prisoners' Dilemma situations, may 'evolve' without communication (Axelrod 1984). If rational choice theory recognizes that communication may matter even for rational utility maxim