Relaxing IIA and the effect on individual power

We allow departures from IIA in Arrow’s framework. Our measure of the extent of a departure is the amount of information needed to socially order a pair of alternatives. We also propose a measure of the scope of an individual’s power. The scope of at least one individual’s power increases in step with a reduction in the amount of information that has to be gathered to socially order two alternatives. This result is also established for correspondences, which select a subset of the feasible set as a function of individual preferences.