State-dependent pricing turns money into a two-edged sword

Strong evidence exists that price/wage durations are dependent on the state of the economy, especially inflation. We embed this dependence in a macro model of the US that otherwise does well in matching the economy's behaviour in the last three decades; it now also matches it over the whole post-war period. This finding implies a major new role for monetary policy: besides controlling inflation it now determines the economy's price stickiness. We find that, when backed by fiscal policy in preventing a ZLB, by targeting nominal GDP monetary policy can achieve high price stability and avoid large cyclical output fluctuations