Edward Glaeser identifies the argument, though he does not present very solid conclusions. This is not his fault; he is constrained by the fact there exists little significant data, and he wishes to maintain both his dignity and his reputation. I will try to explain the problem at Street level, having no reputation to protect. There are only a finite number of Jobs at any given level of Production; this meaning there is a maximum and minimum Work force that will naturally be employed. Stimulus pursues the dream that Employment can be held at the maximum level of employment rather than at the minimum. This is why economists and competent leadership are always talking about Jobs saved, as well as Jobs created, by Stimulus. The trouble arises in the fact that Jobs are of two forms: those creating higher Production levels, and those actually incurring Costs reducing Production levels; I like to call this natural and artificial employment.
Readers can easily understand natural employment, which is anything which pushes Product down the line. This means there is provision of Goods or Services purchased for Consumption, whether Public or Private, which advances the utility of life. Consumers find themselves with enhanced lifestyle, which accelerates their own Productivity or Leisure; here there is placed an economic value to entertainment, a provision of relaxation to readjust for greater future labor. This natural labor presents a Scenario where the benefits of their production exceed their Production Costs, rendering a higher overall Productivity. Everyone wants a higher level of maximized natural labor.
The Case for artificial labor is not clear at all. Here the Production Costs of such labor erode the profitability of all Production, often to the point where the Profits from natural labor are absorbed; the effort draining the Investment capacities deriving from natural labor through taxation, or conquest of Investment funds from public borrowing. The whole mix means that the opportunities of natural labor might be reduced as artificial labor Production Costs, while artificial employment provides no real benefit to Consumers. It is clear that We want no reduction of natural employment under any Conditions, while there is increasing evidence that attempted maximization of overall employment can adversely effect natural employment. The worst effect that can be encountered is discussed by Glaeser, where Stimulus simply replaces natural employment with artificial employment; a factor seemingly present, as little change in Employment occurs, though there has been a vast injection of funds. I now leave it to brilliant economists to explains How this could actually destroy more than it saves. lgl