More Reasons to Resist the Temptation of Power Indices in the European Union

Jan-Erik Lane and Sven Berg, and Manfred Holler and Mika Widgrén, agree that power index analysis of the EU cannot take into account its institutional structure. For us, this is a sufficient condition for its failure as a research program. Nonetheless, they go on to argue that power indices are better suited than our analysis to address questions of institutional design under conditions of uncertainty. We demonstrate, however, that the way they model uncertainty (outcomes are uniformly distributed across the possible `states of the world') means that their conclusions depend heavily on the partition of these states of the world. As a result, power-index-based analyses of institutional design are not informed by the factors that should be included (institutions and strategies) and instead rely on a priori mathematical formulas and analysts' questionable assumptions about the partition of future states of the world.