Alexandria Ocasio-Cortez (D-NY), who told Business Insider in January that MMT “absolutely” needs to be “a larger part of our conversation.” That was the most vocal mainstream support MMT had gotten, which for years had been championed by economists like Stephanie Kelton (a former adviser to Bernie Sanders), L.

Critics have argued that MMT is not a theory because there is no mathematical model. Others have argued that there is a theory but that there is nothing new and, even if there is, it is not valid, it is misleading, and it pushes the logic too far.

Congress did not conduct an “experiment” with MMT. MMT's account of what constrains public spending isn't original. But the policy paradigm its adherents derive from that account is quite novel indeed. Many mainstream economists will acknowledge that inflation is the primary constraint on deficit spending.