The second issue is with regard to what monetary policy tools are desirable under a low natural rate of interest. If the natural rate remains at a relatively low level over the medium to long term, compared with in the past, as suggested by the secular stagnation thesis, then the nominal interest rate is likely to stay around zero.
Furthermore, even after the normalization of interest rates, the nominal rate might fall back to zero or to a very low level. In that case, would unconventional monetary policy continue to be important even “beyond the exit”? Moreover, would it eventually be regarded as conventional in an economy under the “new normal”?