The Fed is in a jam, though, because it faces asymmetric risks. If it raises rates too soon, its scope to cut them, should the economy then sour, is limited by the fact rates cannot fall far below zero. If it waits until inflation is stronger, it has unlimited capacity to raise rates to tame it.
This to me is the key paragraph. Why not wait until we reach or exceed target inflation, when they risk tanking our still very fragile economy, and then being unable to do anything about it since rates would still be close to zero?