Let me start with simple rules. For instance, under the famous k-percent rule proposed by Milton Friedman in 1956, central banks would have to ensure that some specified measure of the money stock rises by a pre-defined fixed rate each year, irrespective of economic conditions and circumstances.
The main problem with such a rule is that it would not accommodate money demand  2  BIS Review 22/2004  shocks, including those of a more permanent nature relating to structural change and innovation in financial markets. This may lead to undesirably high volatility in interest rates, prices and output.