2 Opportunistic manipulations of the monetary policy framework of course damage the foundations on which that framework rests. So, being able to rely on the rebalancing effect of inflation expectations is a superior option. But firmly anchored inflation expectations also make policy commitments unnecessary.
These commitments concerning the future course of the policy rate are viewed as providing one effective instrument for introducing a stimulus when the room for reducing the nominal interest rate is exhausted. But they come at a price. Policy commitments cannot be effective unless they materially constrain future options.