Old-Keynesianism in the New Keynesian Model

I investigate an ‘old Keynesian’ fiscal policy in which government spending endogenously responds to inflation and the output gap when the nominal interest rate is pegged at the ZLB. I do so within a standard Representative Agent New Keynesian model (RANK), as well as a two-period Overlapping Generations New Keynesian model (OLG-NK). For both model versions, I find that the equilibrium values for inflation and the output gap under a standard Taylor rule regime can be replicated under the ‘old Keynesian’ regime. However, a unique stable countercyclical equilibrium is only feasible within the OLG-NK model and crucially depends on the pension system.