A policy of ensuring against a deflation risk, without clear evidence that the risk is materialising, might in fact coordinate agents’ expectations of negative inflation, thus increasing its likelihood. Second, if the transmission of monetary policy does not function properly, the lowering of policy rates is not transmitted to the real economy and is thus not effective.
We can see that in the current environment rates to end users have fallen much less than policy rates. This undermines the confidence on the effectiveness of monetary policy, which might aggravate the problem. It is thus preferable to devote efforts to improve the transmission mechanism, in particular by  3  See O. Issing (2002) and C. Borio and P. Lowe (2002).