In short, there’s a very good case to be made that austerity now isn’t just a bad idea because of its impact on the economy and the unemployed; it may well fail even at the task of helping the budget balance.
It’s important to realize that I’m not saying that government spending always pays for itself, and that saving money is always counterproductive. These kinds of effects are specific to a liquidity trap situation. But that’s the situation we’re in.
More detail in the article.