Of course, he’s in the minority, but this illustrates some of the wacky economic theories that permeate the Left.

Kelton disagrees with Romer and Mankiw on economic theory. In fact, she disagrees with just about every economist Bush or Obama ever hired about economic theory. Kelton is among the most influential advocates of Modern Monetary Theory (MMT), a heterodox left-leaning movement within economics that rejects New Keynesianism and other mainstream macroeconomic theories.

MMT emphasizes the fact that countries that print their own money can never really “run out of money.” They can just print more. The reason we have taxes, then, is not to pay for stuff, but to keep people using the government’s preferred currency rather than, say, Bitcoin. In some rare cases, consumer demand gets too high, so sellers raise prices and inflation ensues. Then, you need to raise taxes to cool the economy down. But the theory holds that this eventuality is pretty rare. James Galbraith, another MMT-influenced economist, once told me that the last time it happened was in World War I.

The main takeaway from this is that you really don’t need to balance the budget over any time horizon, and attempts to do so will hurt the economy. That’s what Kelton argues happened after the Clinton surpluses of the late 1990s / early 2000s. Any dollar of government surplus must show up as private debt, she reasons. And the private sectors just can’t run up debt like that indefinitely. “Eventually, something will give,” Kelton once wrote to Business Insider. “And when it does, the private sector will retrench, the economy will contract, and the government’s budget will move back into deficit.”