Remember the debate about whether central banks should prick bubbles? It was not too long ago that simply asking the question incited abuse. While pricking bubbles is now considered a suitable subject for polite conversion, there is still no agreement on what to do or how to do it. Since bubbles are already building up in several segments of the financial markets, it is time to think about this question in detail.

As I argued last week, there are some deep-rooted causes of the proliferation of bubbles – among them the size of the financial sector; the too-big-to-fail problem; and the banks’ renewed lust for risk. Governments have not been addressing these causes. Central banks will not provide the cure either, but they can address some of the symptoms. Symptoms matter.