Inflation dynamics: Structural shifts and the central bank’s multidimensional toolkit

Central bank’s ability to control inflation

The paper by Laura Castillo-Martinez and Ricardo Reis  provides a unified theoretical framework to explain how central banks achieve price stability, emphasizing the interplay between policy tools, economic forces, and historical context. The authors develop a log-linearized model of price determination, incorporating nominal rigidities (Calvo pricing) and rational expectations. Key equations include the Fisher equation (linking nominal rates to inflation expectations) and a Phillips curve (linking inflation to output gaps). Four distinct strategies are analyzed for determinacy (unique equilibrium) and effectiveness (volatility around the inflation target):

• Interest rate rules  (Taylor principle, forward guidance).
• Monetarist approaches (money supply rules, currency pegs).
• Balance sheet policies  (quantitative easing, yield curve control).
• Fiscal-monetary interactions (central bank solvency, income shortfalls)

Castillo-Martinez and Reis use as case studies the 1970s stagflation, the 1990s inflation targeting, and the post-2008 unconventional policies.

Key findings

1. Interest rate rules
   –Taylor principle: Aggressive feedback rules (raising rates more than 1:1 with inflation) ensure determinacy. However, effectiveness hinges on accurate real-time estimates of the natural rate of interest and transparent communication.
   – Escape clauses: A “monetary pillar” (e.g., committing to money-supply adjustments if inflation deviates) is critical to anchor expectations during crises (e.g., Volcker’s 1980s policies).
   – Bounds on rates: At the effective lower bound (ELB), forward guidance and quantitative easing can stabilize inflation but rely heavily on rational long-term expectations.
2. Unconventional policies
   – Forward guidance: Effectiveness diminishes with longer horizons due to limited household rationality and financial market frictions.
   – Quantitative easing: Reduces long-term yields but faces diminishing returns due to small elasticities in bond demand.
3. Monetarist Approaches
   – Money growth rules: Prone to volatility from shocks to money demand (e.g., financial innovation), as seen in the 1980s UK/US experiments.
   – Exchange rate pegs: Stabilize inflation but fail under fiscal dominance or external shocks (e.g., Latin American hyperinflations).
4. Fiscal Support
   Central bank solvency requires fiscal backing. A reckless fiscal authority can force inflation through debt monetization, as seen in historical hyperinflations.
5. Historical lessons
   – The 1970s high inflation resulted from poor communication, misestimated natural rates, and lack of escape clauses.
   – The 1990s–2000s success of inflation targeting relied on transparency and credible feedback rules.
   – Post-2021 inflation surges highlight risks of neglecting fiscal-monetary coordination and forward guidance limitations.

How do central banks control inflation? A guide for the perplexed
Authors: Laura Castillo-Martinez, Ricardo Reis
From: Duke University, LSE

The long-term path of inflation

Afrouzi et al. analyze long-run inflation dynamics through a modified New Keynesian framework that incorporates political economy factors and non-linear effects of inflation. The authors extend the standard New Keynesian model by allowing for non-zero steady-state inflation and central bank discretion (lack of commitment). Unlike traditional linearized models, this approach captures long-run effects of inflation on price dispersion and aggregate demand. They also introduce long-run aggregate demand (LRAD) and supply (LRAS) curves. The LRAS curve reflects a Phillips curve relationship, while the LRAD curve links inflation to demand via price dispersion. Higher inflation increases dispersion, reducing demand. Finally, the authors assume endogenous central bank pressures as central banks face political economy pressures to inflate due to monopoly power shifts or fiscal constraints.

Key findings

1. Historical drivers of low inflation (1980s–2010s):
   – Globalization and trade liberalization reduced firm monopoly power, lowering inflation.
   – Washington Consensus reforms (privatization, fiscal discipline) and de-unionization weakened labor market power, further reducing inflation.
   – Central bank reforms (independence, inflation targeting) played a role but were insufficient alone; favorable economic conditions were critical.
2. Future inflation risks:
   – Deglobalization: Rising protectionism and geopolitical tensions could increase monopoly power, pushing inflation up.
   – Fiscal pressures: Aging populations, climate policies, and defense spending may force central banks to tolerate higher inflation to manage debt.
   – Unshackling from the zero lower bound: Higher real interest rates reduce de facto central bank hawkishness, increasing inflation pressures.
3. Policy implications:
   – Maintaining low inflation requires stronger central bank independence or credible fiscal policies to counteract upward pressures.
   – Output costs of even small inflation increases (e.g., 2% to 3%) are non-negligible due to price dispersion, especially in input-output networks.

Changing Central Bank Pressures and Inflation
Authors: Hassan Afrouzi, Marina Halac, Kenneth S. Rogoff, Pierre Yared
From: Columbia University, Yale University, Harvard University