"The fiscal stimulus that most advanced economies and emerging markets implemented during the 2008-2009 global recession – together with monetary easing and the backstopping of the financial system – prevented the Great Recession from turning into another Great Depression in 2010. At a time when every component of private demand was collapsing, the boost from higher government spending and lower taxes stopped the global economy’s free-fall and created the basis for recovery.
Unfortunately, stimulus spending and the related bailout of the financial system, together with the recession’s effect on revenues, contributed to fiscal deficits on the order of 10% of GDP in most advanced economies. According to the International Monetary Fund and others, these economies’ ratio of public debt to GDP will surpass 110% by 2015, compared to 70% before the crisis. Aging populations in most advanced economies imply additional public debt in the long term, owing to non-fully-funded pension schemes and rising health-care costs.
Thus, in most advanced economies, deficits need to be reduced to avoid a fiscal train wreck down the line. But much research, including a recent study by the IMF, suggests that raising taxes and reducing government spending has a negative short-term effect on aggregate demand, thereby reinforcing deflationary and recessionary trends – and undermining fiscal consolidation." - in Project Syndicate