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...

There exist social choice rules for which every manipulation benefits everyone. This paper constructs a large variety of rules with this property and provides two characterizations of such rules. Copyright Springer-Verlag Berlin Heidelberg 2014

We identify the maximal number of people who are harmed when a social choice rule is manipulated. If there are n individuals, then for any <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$$k$$</EquationSource> </InlineEquation> greater than 0 and less than n, there is a neutral rule for which the maximal number is <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$$k$$</EquationSource> </InlineEquation>, and there is an anonymous rule for which the maximum...</equationsource></inlineequation></equationsource></inlineequation>

We investigate the implications of relaxing Arrow's independence of irrelevant alternatives axiom while retaining transitivity and the Pareto condition. Even a small relaxation opens a floodgate of possibilities for nondictatorial and efficient social choice.