Lukasz Rachel on Non-Ricardian Macroeconomic Policy and Its Implications for Inflation

Episode Summary

Executive Summary: Lucas Rachel traces the long decline in the neutral real interest rate (r-star) to structural forces like demographics and weaker productivity growth, argues fiscal forces partly offset that decline, and explains why today’s higher real rates may reflect both cyclical and structural shifts. He also shows how non-Ricardian fiscal behavior changes monetary-fiscal interactions and weakens simple Taylor-rule logic.

Main Topics: The decline in r-star and secular stagnation (Priority: 5/5): Rachel and Summers argue that advanced economies experienced a long-run fall in the neutral real rate driven by private-sector saving-investment imbalances, making secular stagnation and the zero lower bound more likely. Fiscal and social spending as upward pressure on rates (Priority: 5/5): The 2019 paper argues rising public debt, social security, and healthcare spending pushed real rates up, partially offsetting an even larger private-sector decline in r-star. Structural drivers of low rates (Priority: 5/5): Demographics, lower population growth, and downward revisions to productivity expectations increase saving, reduce investment demand, and depress the equilibrium real rate. Reassessing r-star after COVID and higher market rates (Priority: 4/5): The newer paper builds a capital-market equilibrium framework to assess whether the post-pandemic rise in real yields is a true structural break or a cyclical correction, emphasizing wealth-to-GDP and transition dynamics. Limited foresight and expectation formation (Priority: 4/5): Rachel argues agents do not have perfect foresight; realistic expectations are crucial for modeling r-star because shocks are learned about gradually, affecting the estimated path of neutral rates. Monetary-fiscal interactions without Ricardian equivalence (Priority: 5/5): In a heterogeneous-agent, non-Ricardian world, deficits directly affect demand and inflation, so the Taylor principle is neither necessary nor sufficient for good outcomes; fiscal and monetary policy are jointly important.

Key Arguments: Private-sector structural forces pulled r-star down substantially; public-sector deficits and social spending pushed it up, but not enough to prevent a secular decline. A deeply negative natural rate would have made monetary policy more constrained by the effective lower bound, worsening stabilization and potentially growth. Demographic aging, slower population growth, and weaker long-run productivity expectations are central to the long-run fall in neutral rates. Post-2008 declines in measured r-star reflect a mix of cyclical shock, deleveraging, and structural revaluation of long-run growth, so trend and cycle should not be conflated. Market real rates rose sharply after COVID, but model-based r-star may have risen much less; some of the rise could be a correction toward fundamentals. Higher safe-rate premiums and changing perceptions of government debt safety can materially affect the safe r-star. In non-Ricardian environments, deficits can raise demand directly, and monetary tightening can feed back through debt-service costs, altering inflation dynamics. The Taylor principle remains useful in standard models, but in non-Ricardian settings it is not sufficient to guarantee determinacy or low inflation. Fiscal responsibility still matters because monetary policy alone cannot fully stabilize inflation and debt when agents are liquidity constrained or do not internalize future taxes.

Data Points: Neutral real rate decline: About 700 basis points in the private-sector r-star counterfactual; roughly 300 basis points after accounting for public-sector forces - From the secular stagnation paper discussed at the AEA meeting Difference explained by public-sector forces: About 400 basis points - The offset between the private-sector decline and the observed decline after deficits/social spending are included Wealth-to-GDP ratio: Rose from about 3 to about 6 over roughly 40 years - Used in the capital-market equilibrium framework to link low rates and rising wealth Starting and current r-star path: Around 5% in 1970 to close to 0% today - Rachel’s long-run estimate in the 2024 Brookings paper Retirement horizon: From about 6-7 years to around 20 years - Illustrates how aging increases desired saving and lowers r-star AI upside scenario: Could raise r-star by about 1 percentage point - A scenario in the r-star toolkit paper based on capital-intensive AI investment and productivity gains Rate dynamics: Long-term real interest rates declined for about three decades up to COVID - Motivating the question of whether the pandemic caused a structural break Public debt and transfers: Government debt-to-GDP ratios much higher post-COVID - Used to motivate fiscal-risk scenarios affecting r-star and inflation Inflation policy lesson: Taylor principle is neither necessary nor sufficient - Main result from the paper on monetary-fiscal interactions without Ricardian equivalence

Pivotal Quotes: "man, were it not for the budget deficits and large stock of debt, the neutral rate would be even lower than it was" — David Beckworth: Beckworth summarizes the central counterfactual from Rachel and Summers’ secular stagnation paper "the Taylor principle is neither necessary nor sufficient" — Lucas Rachel: Core conclusion of the monetary-fiscal interactions paper under non-Ricardian behavior "I do not want firms and households in my economy to be perfectly forecasting the global financial crisis" — Lucas Rachel: Explaining why limited foresight is more realistic than perfect foresight in r-star modeling

Implications: The episode suggests long-run rates may stay structurally low unless productivity, investment demand, or fiscal conditions shift meaningfully. It also warns that fiscal behavior can materially alter inflation dynamics, so monetary policy cannot be analyzed in isolation.