This is exactly a setting where rules would be better than discretion, in particular to avoid the time-inconsistency problem, highlighted in the work of Nobel laureates Finn Kydland and Edward Prescott in 1970s and early 1980s.
In sum, ladies and gentlemen, we see three major trends in the global operating environment. 1)  Multi-speed global growth,  2)  Policy divergence among advanced economies, and  3)  Bouts of financial market volatility as global markets rebalance positions in the face of US dollar strength and volatility in commodity markets.