In this post he concludes:
So if you expect the US and UK economies to be depressed for a long time, with the central bank keeping rates low, long rates will be low too — end of story.
But won’t that money printing cause inflation? Not as long as the economy remains depressed. Budget deficits could lead people to expect higher inflation down the road, once the slump finally ends — but that would be a good thing for the economy in the short run, discouraging people from sitting on cash and weakening the exchange rate, thereby making exports more competitive.
The point, then, is that the whole “credibility” argument is incoherent.
Higher expected inflation down the road is not all higher budget deficits will do. In fact, it´s even unlikely it will help end the slump.