Central bank credibility—the public's belief it will maintain stated inflation target—anchors inflation expectations. Credible targets keep expectations stable, reducing need for recessions to control inflation. Built through consistent policy and transparency; lost quickly through errors.
Compare credible (Germany, Switzerland) versus less credible central banks (historically Latin America). Low-credibility banks have steeper Phillips curves: inflation responds more to unemployment because expectations poorly anchored.
From rational expectations, you know that people form forecasts using all available information, including their beliefs about how policymakers will behave. This insight transforms how we think about monetary policy: what a central bank *announces* it will do matters as much as what it actually does, because announcements shape the expectations that feed back into the economy. Central bank credibility is the measure of how much the public believes those announcements.
To see why credibility matters, consider inflation targeting. A central bank declares it will keep inflation at 2%. If firms and workers believe this fully, they set wages and prices consistent with 2% inflation. Their behavior actually helps produce 2% inflation — the expectation is self-fulfilling. The central bank barely has to do anything: inflation stays near target because everyone acts as if it will. Now contrast this with a low-credibility bank whose 2% target is viewed skeptically. Workers demand higher wages to protect against the possibility of higher inflation; firms raise prices preemptively. The bank faces an inflationary spiral that it must combat with aggressive rate hikes — causing real economic pain — not because inflation has actually risen but because *expectations* have unanchored. The credibility deficit imposes real costs.
The mechanism runs through the Phillips curve. In the New Keynesian framework, current inflation depends on expected future inflation plus a term capturing the gap between actual and potential output. When inflation expectations are well-anchored at the target, the expectations term is stable, and the central bank can respond flexibly to output shocks without worrying that inflation will spiral. When expectations are poorly anchored, every output shock raises the risk of a wage-price spiral, forcing the bank to respond more aggressively than it otherwise would. A credible bank has, in effect, purchased insurance against expectation-driven inflation — at the cost of building and maintaining that credibility through consistent behavior over years.
Credibility is earned, not granted, and can be lost quickly. The Bundesbank built decades of credibility through consistent anti-inflationary policy after the hyperinflation trauma of the 1920s. The U.S. Federal Reserve lost credibility during the 1970s through repeated accommodation of inflationary shocks, and Paul Volcker's painful 1979–82 disinflation was the price of rebuilding it — short-term interest rates above 20% and a deep recession. The asymmetry is important: building credibility takes years; losing it can happen in months. This is why central banks place such emphasis on institutional independence, clear communication, and operational transparency — not as bureaucratic formality but as deliberate investments in expectation management.