The general economic principle in play is that the government should act counter-cyclically. That is, it should tax high and spend low during good years, then t

The general economic principle in play is that the government should act counter-cyclically. That is, it should tax high and spend low during good years, then tax low and spend high during bad years. What the government spends the money on is not particuarly relevent [0]. Hiring an army to fill in ditches that your other army digs would serve this purpose just fine. If you are able to spend this money doing productive work, that is a plus; but not particularly relevant to the core economics. Of course, the problem with this economic philosophy is that it can be difficult to implement given political constraints. During bad years, there is a sense that the government needs to tighten its bootstraps, and during good years there is a sense that the government has the money to invest. While this is a good philosophy for household budgeting, it just turns the government into a pro-cyclic actor, which is the opposite of what we want. [0] As long as the money makes it throughout the economy that is.