In a very broad class of dynamic linear models, if agents possess knowledge of current endogenous variables in a least-squares learning process, determinacy of a rational expectations (RE) equilibrium is sufficient but not necessary for learnability of that equilibrium. Thus, since learnability...

Bennett McCallum (2009), applying Evans and Honkapohja's (2001) results, argues that "learnability" can save New-Keynesian models from their indeterminacies. He claims the unique bounded equilibrium is learnable, and the explosive equilibria are not. However, he assumes that agents can directly...

This paper investigates the role that imperfect knowledge about the structure of the economy plays in the formation of expectations, macroeconomic dynamics, and the efficient formulation of monetary policy. Economic agents rely on an adaptive learning technology to form expectations and to...

In a plain-vanilla New Keynesian model with two-period staggered price-setting, discretionary monetary policy leads to multiple equilibria. Complementarity between the pricing decisions of forward-looking firms underlies the multiplicity, which is intrinsically dynamic in nature. At each point...

How do Bitcoin prices evolve? What are the consequences for monetary policy? We answer these questions in a novel, yet simple endowment economy. There are two types of money, both useful for transactions: Bitcoins and Dollars. A central bank keeps the real value of Dollars constant, while...

This paper examines monetary policy in Rudebusch and Svensson's (1999) two equation macroeconomic model when the policymaker recognizes that the model is an approximation and is uncertain about the quality of that approximation. It is argued that the minimax approach of robust control provides a...

In analyses of "liquidity trap" problems associated with the zero lower bound (ZLB) on nominal interest rates, it is important to emphasize the difference between policy rule changes, intended to help escape an existing ZLB situation, and maintained policy rules designed so as to avoid ZLB...

We show analytically that in a rational expectations present value model, an asset price manifests near random walk behavior if fundamentals are I(1) and the factor for discounting future fundamentals is near one. We argue that this result helps explain the well known puzzle that fundamental...

This paper discusses four current topics in monetary policy analysis, each of which hinges on the possibility of multiple solutions in rational expectations (RE) models. In three of these cases--involving inflation forecast targeting, the zero-lower bound deflation trap, and the fiscal theory of...

This paper proves a certainty equivalence result for optimal policy under commitment with symmetric partial information about the state of the economy in a model with forward-looking variables. This result is used in our previous paper, Indicator Variables for Optimal Policy,' which synthesizes...