Is it possible that the US and other major global economies might not return to full employment and strong growth without the help of unconventional policy support? I raised that notion – the old idea of “secular stagnation” – recently in a talk hosted by the International Monetary Fund.

My concern rests on a number of considerations. First, even though financial repair had largely taken place four years ago, recovery has only kept up with population growth and normal productivity growth in the US, and has been worse elsewhere in the industrial world.

Second, manifestly unsustainable bubbles and loosening of credit standards during the middle of the past decade, along with very easy money, were sufficient to drive only moderate economic growth. Third, short-term interest rates are severely constrained by the zero lower bound: real rates may not be able to fall far enough to spur enough investment to lead to full employment.