Majority voting with stochastic preferences: the whims of a committee are smaller than the whims of its members

This note studies the volatility of the policy chosen by a committee whose members’ preferences are volatile, due to common and individual preferences shocks. It is shown that majority voting mitigates the latter but not the former. The volatility of the policy is smaller the smaller the volatility of members’ preferences, smaller the larger the size of the committee, and smaller than if it was chosen by a single member. The results hold in a context of uncertainty and with multidimensional issues.