Partially Binding Platforms: Political Promises as a Partial Commitment Device

This paper examines the effects of campaign platforms in political competition when campaign platforms are partially binding: a candidate who implements a policy different from his/her platform must pay a cost of betrayal that increases with the size of the discrepancy. With partially binding platforms, the median-voter theorem does not hold, and candidates always implement different policies in equilibrium. If and only if the cost of betrayal goes to infinity for any degree of betrayal, the median-voter theorem holds. Partially binding platforms also can predict who wins. A candidate who is more moderate, less policy-motivated and whose cost of betrayal is higher than the opposition with the same degree of betrayal wins. The degree of honesty can be derived endogenously, and candidates who have the above characteristics are more honest.