Keynesian theory initially prevailed because it did a far better job than classical orthodoxy of making sense of the world around us, and Friedman’s … - Paul Krugman

So the story of the baby-sitting co-op is not a mere amusement. If people would only take it seriously—if they could only understand that when great economic issues are at stake, whimsical parables are not a waste of time but the key to enlightenment—it is a story that could save the world.

Here’s what the IMF did: In Asia (as opposed to Brazil, which as I said was a sort of caricature of the Asian programs) it did not tell countries to defend the values of their currencies at all cost. But it did tell them to raise interest rates, initially to very high levels, in an attempt to persuade investors to keep their money in place. Some vociferous critics of the IMF—most notably Harvard’s Jeffrey Sachs—said that this was very much the wrong thing to do. Sachs believed, in effect, that Asian countries could and should have behaved like Australia, simply letting their currencies decline until they started to look cheap to investors, and that if they had done so, the great slump would never have happened.
What the IMF said in response is that Asia is not Australia: that to let the currencies fall unchecked would have led to “hyperdevaluations,” and that the result would have been both massive financial distress (because so many businesses had debt denominated in dollars) and soaring inflation. The trouble with this rationale is, of course, that the massive financial distress happened anyway, thanks to high interest rates and the recession they helped cause. So the IMF at best avoided one vicious circle only by starting another.

I would summarize the Keynesian view in terms of four points: 1. Economies sometimes produce much less than they could, and employ many fewer workers than they should, because there just isn’t enough spending. Such episodes can happen for a variety of reasons; the question is how to respond.
2. There are normally forces that tend to push the economy back toward full employment. But they work slowly; a hands-off policy toward depressed economies means accepting a long, unnecessary period of pain.
3. It is often possible to drastically shorten this period of pain and greatly reduce the human and financial losses by “printing money”, using the central bank’s power of currency creation to push interest rates down.
4. Sometimes, however, monetary policy loses its effectiveness, especially when rates are close to zero. In that case temporary deficit spending can provide a useful boost. And conversely, fiscal austerity in a depressed economy imposes large economic losses.