Stephanie Kelton, a leading advocate of the theory, is, as you might expect, not having it.

This debate so far has featured plenty of abstract macroeconomic theory, but also dueling rhetorical styles and no small amount of insider vs. outsider dynamics. M.M.T. people are the insurgents who view their antagonists as a calcified elite, and that establishment views the M.M.T. people as gooey idealists. Ms. Kelton and other adherents of the theory are seemingly on a journey from outsider to insider.

But for all the digital ink spilled on this topic in recent weeks on the pure economics of the theory, there has been surprisingly little discussion of the practical implications for how economic policy would work.

For example, a core idea behind the theory is that Congress should spend money as it sees fit, and that its only constraints should involve the available real-world resources of labor and materials to carry out those spending ambitions. In this model, inflation is the sign that spending needs to be reined in or taxes raised.

But it might be too much to expect Congress to move with foresight and wisdom in applying the brakes at the right time. Elected officials have tended to have exactly the opposite instincts of M.M.T advocates. In 2011, Congress demanded deficit reduction at a time of deflation risks and weak growth. In 1981, the Reagan administration and Congress enacted tax cuts and military spending increases at a time of double-digit inflation.

It’s fine to criticize the performance of the Federal Reserve — the institution with primary responsibility for stabilizing the economy under the current economic system­ — for bad decisions over the years. But anyone who has watched the sometimes off-the-wall questions at congressional oversight hearings of the Fed over the last decade would be unlikely to conclude that the lawmakers have a better understanding of economic policy.