When a big economy hits the shoals, there are options.
You can take a Keynesian approach. You can take a Friedmanian approach. There are Bernankes, there are Nodas , the Austrian School, the Chicago School, expansion and contraction - however a government wants to play it, whatever the ideology, there are options and precedents for getting the economy going again.
But there are some problems, some threats that can't be addressed with an easy, take-your-pick policy. These would be the problems posed by simple demographics. Some of the world's biggest economies and most crucial players are facing true demographic crises which, if left untended, will ultimately result in their downfall. These countries are facing demographic time bombs.