How Paul Volcker Broke Up with Milton Friedman’s Favorite Equation
For decades, the central dogma of macroeconomics was seduced by a tidy equation: if you want to know how hot the room will get, count the units of fuel sitting in the shed. The logic seemed bulletproof. Flood an economy with paper money, and the inevitable consequence must be an equivalent dilution of purchasing power. Milton Friedman’s famous aphorism—that inflation is always and everywhere a monetary phenomenon—was treated not as a conditional hypothesis, but as an iron law of nature. Yet modern economic history has repeatedly embarrassed this mechanical view. In the years following the 2008 financial crash, central banks printed trillions to recapitalize the financial system; mainstream hyperinflation predictions failed entirely. Conversely, when severe inflation arrived over a decade later, it was driven as much by snarls in microchip supply, shuttered ports, and energy shocks as it was by direct liquidity injections. The persistent error lies in mistaking money aggregates—M1, M2, ...