Despite James Mackintosh’s suggestion in “Streetwise: Modern Monetary Theory Isn’t Coming in the Future. It’s Here Now” (Markets, Nov. 22), MMT remains a niche theory endorsed by only a small but vocal group of far-left economists. Even mainstream but left-leaning economists eschew MMT. Lawrence Summers called MMT “a recipe for economic disaster.” Paul Krugman said the theory “seems just obviously indefensible.”

Mr. Mackintosh may have been misled by recent history in his claim that “government spending does far more for inflation...

Dollar bills are curled and inspected during production at the Bureau of Engraving and Printing in Washington, Nov. 14, 2014.

Photo: gary cameron/Reuters

Despite James Mackintosh’s suggestion in “Streetwise: Modern Monetary Theory Isn’t Coming in the Future. It’s Here Now” (Markets, Nov. 22), MMT remains a niche theory endorsed by only a small but vocal group of far-left economists. Even mainstream but left-leaning economists eschew MMT. Lawrence Summers called MMT “a recipe for economic disaster.” Paul Krugman said the theory “seems just obviously indefensible.”

Mr. Mackintosh may have been misled by recent history in his claim that “government spending does far more for inflation than quantitative easing.” QE following the Great Recession was mostly sterilized by the Fed’s policy of paying interest on bank reserves held at the Fed. Most research finds that increases in fiscal spending increase total spending only when the economy is in recession. Fiscal spending can drive up prices only through real activity rather than the broad-based inflation caused by monetary policy.

Thomas Hogan

American Institute for Economic Research

Great Barrington, Mass.

MMT is still a crazy idea. It is analogous to consumers who argue that their credit-card balances don’t matter. Consumer credit-card balances matter when the card is declined at the gas pump, just as our federal debt will matter when we can no longer roll it over.

Jim Chaput

Oakwood, Ga.