The IMF and others impose austerity measures on government to pay down their debt and to increase investor confidence in countries. The result over the longer term is supposed to be increased investor confidence, a more competitive economy for the country and hence economic growth. But is the empirical evidence or even theory supportive of this viewpoint?
First in terms of what one would expect in theory. Austerity would be expected to decrease demand but if there is decreased demand then less production is needed to fill that demand. Therefore other things being equal austerity would tend to decrease production rather than increase it.
Harvard economist Alberto Alesina shows that government debt reduction by expenditure cuts and tax increases does not always have negative effects. However an IMF study of 17 countries that implemented austerity plans in the last 30 years showed that debt reduction plans that were intended to reduce debt and lead to prosperity on the whole did not do so. Some of the positive results in the earlier study were cases where the aim of austerity was sometimes to cool down an overheated economy and this was often successful with growth continuing but at a less heated rate.
The overall findings of the IMF study of austerity policies designed to reduce debt were that consumption expenditure declined and the economy was weaker. This is what one would expect. Greece is a good empirical example of where this is happening with the country actually going into a recession. Some critics question the results but nevertheless the empirical data give at least some support to critics of austerity programs who claim that stimulus rather than austerity is the more sensible policy over the short term to help an economy grow and produce more revenues to then pay down debt. For more see this article.
Given that the IMF's own study shows that their policies reduce economic growth why would they continue to recommend them. Because these policies do please investors. They weaken labor and lower labor costs. The point is not to grow the economy but to increase the power of capital over labor. The policies do that. Economic growth per se is not the aim but growth in profits. In the longer term after labor is crushed, pension benefits eroded, the safety net mostly gone, then as the theory has it the country will be more competitive, Perhaps investors may return. Of course many workers may have long ago migrated to areas with better prospects. Ireland apparently is already seeing renewed emigration as the boom there has given way to austerity.