Olivier Blanchard over at the IMF's blog (via Paul Krugman):
Third, financial investors are schizophrenic about fiscal consolidation and growth.
They react positively to news of fiscal consolidation, but then react negatively later, when consolidation leads to lower growth—which it often does. Some preliminary estimates that the IMF is working on suggest that it does not take large multipliers for the joint effects of fiscal consolidation and the implied lower growth to lead in the end to an increase, not a decrease, in risk spreads on government bonds. To the extent that governments feel they have to respond to markets, they may be induced to consolidate too fast, even from the narrow point of view of debt sustainability.
I should be clear here. Substantial fiscal consolidation is needed, and debt levels must decrease. But it should be, in the words of Angela Merkel, a marathon rather than a sprint. It will take more than two decades to return to prudent levels of debt. There is a proverb that actually applies here too: “slow and steady wins the race.”