Myths and Meanings of Voting Power

These are comments on the Symposium `Power Indices and the European Union' in the July 1999 issue of this Journal. We point out several common inter-connected confusions and errors concerning the meaning of voting power. We stress the vital distinction between two different intuitive notions of voting power. We emphasize the need for a unified approach to the study of a priori and actual voting power. We show that the family of `strategic' measures proposed by some of the participants in the Symposium are a natural generalization of the Banzhaf measure