Good discussion. I've long been wary of deficit spending, but more recently I started listening to economist Richard Duncan who shows that since the rise of globalization, inflation has gone away. We can't overheat our economy because now we are trying to overheat the global economy. Japan has printed way more money than us relative to the size of their economy, and they can't get anything resembling inflation to take hold at all.
He says that we could print tremendous amounts of money to solve problems like cancer, global warming, etc with very little repercussion. Of course, this only holds as long as globalization holds, and the recent retreat from free trade may help bring inflation back to our shores.
I'm not an economist and don't pretend to know the answer, but it is fun to follow along.