When modern monetary theory began to emerge into popular consciousness almost two years ago it carried with it an odour of coming from the distant economic fringe. Opposed by many traditional economists from both the left and the right, MMT as it became popularly known, was the idea that governments didn’t have to raise new taxes to increase spending. Instead, like the funding for the Second World War, governments that controlled their own currencies, claimed the theory, could borrow from their own central banks and keep on spending, creating economic growth and jobs until inflation finally kicked in. Only a year and a half after I first wrote about MMT as a radical idea that effectively offered a bottomless piggy bank for new government spending, it appears that the fringe is going mainstream.