Rationalizable voting

We derive necessary and sufficient conditions in order for binary voting choices over a finite number of pairs of alternatives to be consistent with voter preferences that admit concave utility representations. These conditions imply simple testable restrictions on the location of voters’ ideal points, and can be used to predict individual voting behavior. On the other hand, if the location of voting alternatives is unrestricted then voting decisions impose no testable restrictions on voter ideal points, even if the space of alternatives in one dimensional. Finally, we show that two dimensions are always sufficient to represent any voting records and voters with strictly concave utility representations and arbitrary ideal points.