The Making of Optimal and Consistent Policy: An Analytical Framework for Monetary Models

This paper shows that optimal policy and consistent policy outcomes require the use of control-theory and game-theory solution techniques. While optimal policy and consistent policy often produce different outcomes even in a one-period model, we analyze consistent policy and its outcome in a simple model, finding that the cause of the inconsistency with optimal policy traces to inconsistent targets in the social loss function. Control theory can identify the optimal plan and, thus, the optimal economic outcomes. Then, we can seek a consistent plan that coincides with the optimal plan through institutional design. That is, the optimal plan can indicate how to design the optimal institution, through which we implement the optimal plan with a consistent plan.