Krugman is puzzled by the European Central Bank:

I’ve been hearing various attempts to explain the ECB’s utterly bizarre refusal to cut interest rates... The most popular story seems to be that the ECB wants to “hold politicians’ feet to the fire”, letting them know that they won’t get relief unless they do what’s necessary (whatever that is). This really doesn’t make any sense. If we’re talking about enforcing austerity and wage cuts in the periphery, how much more incentive do these economies need?

He is certainly right that if the goal is resolving the crisis, or even price stability, then refusing further rate cuts is mighty strange. But who says those are the goals? His final question is meant to be rhetorical, but it really isn't. Because the more austerity you want, the more enforcement you need.

[....]

It's a tenet of liberalism -- and a premise of the conversation Krugman is part of -- that there are conflicting opinions, but not conflicting interests. But sometimes, when people seem to keep doing things with the wrong outcome, it's because that's the outcome they actually want. Paranoid? Conspiracy theory? Maybe. On the other hand, here's Deutsches Bundsbank president Jens Weidmann:

Relieving stress in the sovereign bond markets eases imminent funding pain but blurs the signal to sovereigns about the precarious state of public finances and the urgent need to act. Macroeconomic imbalances and unsustainable public and private debt in some member states lie at the heart of the sovereign debt crisis. It may appeal to politicians to abstain from unpopular decisions and try to solve problems through monetary accommodation. However, it is up to monetary policymakers to fend off these pressures.

That seems pretty clear. From the perspective of the central banker, resolving the crisis too painlessly would be bad, because that would allow governments to "avoid unpopular decisions." And it's true: If there's something you really want governments to do, but you don't think they will make the necessary decisions except in a crisis, then it is perfectly rational to prolong the crisis until you see the right decisions being made.