For a start, we need to embrace this uncertainty. We cannot be dogmatic. We need to take a broad perspective and make sure that our decisions are robust by choosing policies that would be desirable under different types of expectation formation. This is another important reason why monetary policy cannot simply follow mechanistic and simplistic rules.
Otherwise, there might arise the suspicion that the Eurosystem does not take the prohibition of monetary financing so seriously. That was something Mario Draghi clearly pointed out, too.