Monetarism
Monetarism is a macroeconomic school of thought, principally associated with Milton Friedman, holding that changes in the money supply are the primary determinant of nominal economic activity and inflation, and that central banks should focus on steady, predictable money supply growth rather than active economic stabilization.
Monetarism rose to prominence in the 1960s and 1970s as a direct challenge to the Keynesian consensus that had dominated postwar macroeconomic policy. At its core, monetarism rests on a reformulation of the classical quantity theory of money: MV = PQ, where M is the money supply, V is the velocity of money, P is the price level, and Q is real output. Monetarists argued that V — the velocity of money — is relatively stable in the short run, meaning that changes in M translate predictably into changes in nominal GDP (P times Q).
Milton Friedman's most influential monetarist argument was the natural rate of unemployment hypothesis. Friedman argued that there is a natural rate of unemployment consistent with stable inflation — determined by structural features of the labor market such as search frictions and skill mismatches — and that attempts by policymakers to hold unemployment below the natural rate through monetary stimulus will produce only temporary gains before triggering accelerating inflation. This analysis directly explained the stagflation of the 1970s: years of Keynesian demand stimulation had pushed unemployment below its natural rate, generating inflationary pressure that could not be suppressed without accepting higher unemployment.
The most dramatic real-world test of monetarism came under Federal Reserve Chairman Paul Volcker from 1979 to 1982, when the Fed shifted from targeting interest rates to targeting monetary aggregates in an effort to break the inflationary spiral that had plagued the U.S. economy for most of the 1970s. The Volcker Shock — deliberately allowing short-term interest rates to rise to nearly 20% — caused severe recessions in 1980 and 1981-1982 but ultimately broke the back of inflation, validating the monetarist prescription in the view of many economists.
For financial markets, monetarism's legacy is significant. The central bank credibility framework that governs modern Fed communications — inflation targeting, forward guidance, and the emphasis on managing inflation expectations — derives substantially from monetarist insights. Equity markets are acutely sensitive to monetary policy, and understanding the theoretical foundations of how central banks think about money supply, inflation, and output tradeoffs is essential for interpreting Fed decisions and their likely market impact.
Modern central banking has moved away from strict monetary aggregate targeting — in part because the relationship between money supply growth and inflation proved less stable in the 1980s and 1990s than monetarists predicted — but the underlying monetarist insight that excessive money supply growth generates inflation remains foundational to how central banks approach their mandates.