Abstract
This paper examines the implications of different monetary and fiscal policy rules in an economy characterized by Harrodian instability. We show that (1) a monetary rule along Taylor lines can be stabilizing for low debt ratios but becomes de-stabilizing if the debt ratio exceeds a certain threshold, (2) a ‘Keynesian’ fiscal policy rule can stabilize the economy at full employment, (3) a fiscal ‘austerity’ rule that links fiscal parameters to deviations from a target debt ratio fails to adjust the ‘warranted’ to the ‘natural’ growth rate and destabilizes the warranted path and (4) instability may arise from a combination of fiscal and monetary policy rules which separately would stabilize the system.