You can almost hear the great wheels of global monetary policy making turning: change is afoot in each leading central bank. The US Federal Re-serve has bought its last long-term bond. The Bank of England is talking down the prospect of rate rises (after talking it up not long ago). The Bank of Japan is speeding up money creation. Even the European Central Bank is creeping towards asset purchases.

This is not a bad time to assess how much we can demand from central banks. It is fashionable to say monetary policy is “overburdened” and only fiscal policy can help depressed economies out of their rut. I do not dispute the importance of using fiscal policy where there is room for manoeuvre (as in the eurozone as a whole, where the fiscal deficit is only 2.5 per cent of output). Structural reforms are needed, too. But we should take issue with the idea monetary policy has done as much as it can.

The notion that developed economies are in a “liquidity trap” – where printing money no longer has any effect – is treacherous. The problem is partly semantic but semantics can shape politics. A trap is hard to spot and difficult or impossible to escape. The implication is that monetary policy makers have done everything possible. In liquidity trap models of the economy, the central bank is impotent. Although it can create money at will, this power no longer provides influence over interest rates or the ability to give the economy a boost.