In 2012 under Ben Bernanke, the Fed publicly announced that their inflation target would be at 2%, which was already for some time the informal target rate.
But today the FOMC believes the long-term natural funds rate to be at about 3-3.25%. Given that in the past three recessions the Fed lowered rates by an average of 5.79%, this is not enough "ammunition" to combat the next recession.
Some economists have argued to change the target rate to 4% (Ball, 2014), and others have argued for other methods like setting a targeted range of inflation rates (Ed Rosengren, Boston Fed president) while others still have proposed a price-level targeting framework rather than an inflation-rate targeting framework (John Williams, SF Fed president).
Is a change necessary in the long-term? What possibilities should be explored?