These reasons include the need for preemptive policymaking, the importance of taking account of the changing structure of the economy, and the value of what he terms a risk-management approach to policy. I will discuss each of these briefly. Preemption refers to the idea that policymakers achieve better results when they act in advance to forestall developing problems.
Early action works best both because monetary policy works with a lag and because developing problems (such as rising inflation) may often be defused at lower cost in their early stages.