(b)  Countercyclical capital:  Regulators may have to contend with situations which have no precedents and where enough data and analytics are not available and yet the cost of inaction may be high. This requires taking a judgment call and respond with policy measures whose outcome may not be known with a great degree of certainty.
The common idea behind price-level targeting or nominal GDP targets is that, following a period of low inflation or weak growth, monetary policy tolerates higher inflation rates for a time before returning to the target path, thereby giving the economy an additional shot in the arm. I am sceptical of these proposals.