What has happened is that thanks to the machines we work less hours, in better working conditions (the machies do the harsh work) and we enjoy a better standard of living. So please lets stop the crazyness, we need more automatition so we have to work less hours and have an even better standard of living.
Yes, reduce working hour is actually a very good way to solve this problem, and it is very scaleable!
Let's say from tomorrow, all the people who have the job should only work 4.5 days a week, at the same time their salary reduced by 10%. What happens then? All the companies will have to use those saved 10% salary payment to hire 10% more workers to keep the productivity up, then the jobless problem solved right away!
While I agree, with our technologically advanced society, we should be working less and enjoying our lives more. Not out of necessity, but pleasure!
To your credit, the German government when studying the implications of expanding the work week noted that people were in fact much more productive in the first hour than the last hour. So it would seem that cutting hours would have a productive benefit, if they could be made up for by fresh yet unemployed workers. It must also be noted that despite official limits, Germans tend to work five extra hours anyway. I would assume similar numbers apply to workers the world over.
It is still a fallacy to believe that reduced hours with a proportionally increased work force is a productivity wash, particularly in a recession. Consider that drops in employment already lag behind production. One must assume that the least productive workers were laid off first. A reduced work week would cut the most productive workers to the benefit of the least productive and to the detriment of total productivity.
The difference per worker in unskilled labour is very little, so your idea might work in factories. However, this would be a terrible policy in highly skilled labour where worker productivity differs by orders of magnitude, which many software developers here must have observed first hand.