The rationale is that a higher inflation objective, if credible, would prompt firms and households to revise their expectations regarding future inflation upwards. By doing so, it would reduce further down real interest rates, which are not necessarily constrained by zero.
As real – rather than nominal – interest rates matter for economic decisions such as investment and consumption, this change should promote economic activity. It is therefore argued that switching to a higher numerical aim for inflation will bring about a one-off accommodative effect when it is adopted.