We can deal with unemployment every bit as effectively by having people work fewer hours, as we can by increasing demand.
The most important point to realize is that the problem facing wealthy countries at the moment is not that we are poor, as the stern proponents of austerity insist. The problem is that we are wealthy. We have tens of millions of people unemployed precisely because we can meet current demand without needing their labor.
There is nothing natural about the length of the average work week or work year and there are, in fact, large variations across countries. The average worker in Germany and the Netherlands puts in 20% fewer hours in a year than the average worker in the United States. This means that if the US adopted Germany’s work patterns tomorrow, it would immediately eliminate unemployment.