[brc]

The whole point of Keynesian theory is that, in times of economic contraction ('a glut' in the old money), you should borrow from the future and buy things - any things - now.

You could make the argument that buying worthwhile things - like dams or power stations - makes this true. But for two things : if it's worth building a dam for positive return, you should do it at any time, as soon as you can. The second is that governments do not spend money on buying good things. In 2008/9 they spent money buying and crushing old cars, which is about as close to paying people to dig holes and fill them in as you can get.

The believers in 'aggregate demand is all' absolutely do believe that giving people money makes us all richer. They may not say it like that, but that's what they mean.