Do we need a crisis to reduce the deficit?: The macroeconomic case for not cutting the deficit straight after a major recession is as watertight as these things get, at least outside of the Eurozone. (It is also true for the Eurozone, but just a bit more complicated, so its easier to just focus on the US and UK in this post.) If you want to bring the government deficit and debt down, you do so when interest rates are free to counter the impact on aggregate demand. As the problems of high government debt are long term there is no urgency for debt reduction, so the problem can wait. The costs of fiscal consolidation in a liquidity trap are large and immediate, as we have experienced to our cost.
Sometimes austerity proponents will admit this basic macroeconomic truth, but say that it ignores the politics. Politics means that it is very difficult for governments to reduce debt during booms, they say. Although it would be nice to wait for interest rates to rise before cutting the deficit, it will not happen if we do, so we have to cut now. Like all good myths, this is based on a half truth: in the 30 years before the recession, debt tended to rise as a share of GDP in most OECD countries. And it always sounds wise to say you cannot trust politicians.
However both the UK and US show that this is not some kind of iron law of politics. ...