A Theory of Legitimacy

We develop a formal theory of legitimate collective choice. In our theory a policy choice is legitimate if the process through which the final choice was determined is consistent with some principle that can be used to (perhaps partially) rank the potential policy choices. The set of principles in any choice situation is taken to be exogenous, but a decision-making process is defined so as to deal with any nontrivial set of principles. Such a process is itself referred to as legitimate if it is guaranteed to select a legitimate outcome for each possible exogenous set of principles. We characterize the class of procedures that are instrumentally legitimate, prove that legitimate policy decisions consistent with principles always exist and characterize the set of policy decisions that are legitimate for a any given set of principles. Because we do not require the principles to be weak orders of the alternatives, our theory provides a notion of legitimacy that can be satisfied even when the guiding principles are potentially cyclic or incomplete. Accordingly, our theory illustrates one non-tautological means by which majoritarian principles can be reconciled with legitimacy. PRELIMINARY AND INCOMPLETE. COMMENTS WELCOME. Prepared for the 2009 Annual Meetings of the Midwest Political Science Association. ∗Department of Government, Harvard University. Email: [email protected] †Department of Government, Harvard University. Email: [email protected] 1