This paper examines optimal monetary policy under heterogeneous expectations. To this end, we develop a stochastic New Keynesian model with a cost-push shock and coexistence of one-step-ahead rational and adaptive expectations in decentralized markets. On the one side, heterogeneous expectations imply an amplification mechanism that has many adverse consequences missing under the rational expectations paradigm. On the other side, even discretionary optimal monetary policy can manipulate expectations via a novel channel. We argue that the incorporation of heterogeneous expectations in both the design and implementation of discretionary optimal monetary policy to exploit this channel lowers macroeconomic volatility. We find that: (1.) a more hawkish policy can reduce losses due to volatility, but an overly hawkish policy does not; (2.) overestimating the share of rational expectations in the design and implementation of policy creates additional losses, while the underestimation does not; (3.) credible commitment eliminates or mitigates many of the ramifications of heterogeneous expectations.

本文研究了异质预期下的最优货币政策。为此，我们开发了一个随机的新凯恩斯主义模型，在去中心化市场中，具有成本推动冲击和提前一步理性和适应性预期的共存。一方面，异质预期意味着一种放大机制，在理性预期范式下，该机制缺少许多不利后果。另一方面，即使是自由裁量的最优货币政策也可以通过一种新的渠道来操纵预期。我们认为，在可自由支配的最优货币政策的设计和实施中纳入异质预期以利用这一渠道可以降低宏观经济波动。我们发现： (1.) 更鹰派的政策可以减少波动造成的损失，但过于鹰派的政策不会；(2. ) 在政策的设计和实施中高估理性预期的份额会产生额外的损失，而低估则不会；(3.) 可信承诺消除或减轻了异质期望的许多后果。