It’s a very delicate balance, but the Federal Reserve, the Bank of England and the ECB have all done it and succeeded. 3/7  BIS central bankers' speeches  Central bankers in some circumstances have to be bold and fast, but they also have to do things in a politically and legally acceptable manner.
The first reason is that the CPI -- the price statistics that many central banks refer to -- has a statistical tendency of demonstrating a slightly higher inflation rate than the actual one.