This paper extends the benchmark New-Keynesian model by introducing two frictions: (1) agent heterogeneity with incomplete markets, uninsurable idiosyncratic risk, and occasionally binding borrowing constraints; and (2) bounded rationality in the form of level-k thinking. Compared to the...

This paper extends the benchmark New-Keynesian model with a representative agent and rational expectations by introducing two key frictions: (1) agent heterogeneity with incomplete markets, uninsurable idiosyncratic risk, and occasionally-binding borrowing constraints; and (2) bounded...

A number of consequences emerge. (i) Fiscal stimulus or \helicopter drops of money" are powerful and, indeed, pull the economy out of the zero lower bound. More generally, the model allows for the joint analysis of optimal monetary and fiscal policy. (ii) The Taylor principle is strongly...