I'm going to try to put this in a way that perhaps even a Libertarian or Tea Partier could understand. The caller in this video as Senator Sanders said laid out real well or perfectly as I would put it what demand side economics is. Which is when someone invests in something or creates a new product or service that people want at an affordable rate that investment will pay for itself because of the consumer demand that it will bring in return with people buying that product or service. And then of course the money that goes back in the economy and the jobs that get created as a result.
As far as government is concern when it comes to investment. I'm not here to try to make a case that all government investment is good and good for the economy. Or as let's say the further left is concern "all non-defense or security related investment is good for the economy". Why because people who actually believe in that do enough of that all the time. But the things that government should be investing in as it relates to the economy they should be investing in it a hell of a lot more and do it in a fiscally responsible way. And infrastructure investment is a perfect example of that.
Government awards money to construction companies to fix and build new infrastructure and now what do you have, but companies with work to do and of course they need workers to do the work. So that is where the jobs come in and now people who weren't working last week and collecting a public assistance check are working this week collecting a solid pay check for the work they do. What do they do with that money is pay off current bills that they didn't have the money for previously. But each further check goes into the economy to pay those workers bills and for them to live well and enjoy life. Which creates new jobs because of the new consumer demand.
Demand side economics is a term that I wish I've been using a long time ago. But that is exactly what it is and a role and not the only role, but a role that government has in seeing that certain projects that the country needs for the economy to be as strong as possible get done and gets done in a fiscally responsible manner. Which puts money in the economy and creates new jobs as well.