Pity the central bankers who think they are exploring bold new ways to cure the world economy, only to be accused of spreading dangerous diseases. And who find that those they are trying to help — governments in economic pain — look determined to make their task impossible.

Economists are still debating the rights and wrongs of the response of governments and central banks to the 2008 financial shock and the subsequent euro crisis. But there is no arguing that, back then, both sides were at least trying to pull in the same direction, acting together with a strong mutual understanding of what they were aiming at.