Hirano & Stiglitz (2025): Overlapping Generations Models, Multiplicity of Steady States and Momentary Equilibria, and Economic Fluctuations

Summary

"Overlapping generations models, multiplicity of steady states and momentary equilibria, and economic fluctuations," by Tomohiro Hirano and Joseph E. Stiglitz, published in the Oxford Review of Economic Policy 41(2), 2025, pp. 260–290 (DOI: 10.1093/oxrep/graf026; also circulated as NBER Working Paper 34193) — appearing in the same Oxford Review issue as, and immediately preceding, the program's flagship "Henry George" paper (pp. 326–357). This paper's model contains no land. It is the general mathematical-economics foundation for the entire Hirano-Stiglitz research program: a proof, using quite general utility and production functions, that even the simplest possible textbook OLG model can exhibit multiple steady states, multiple momentary equilibria, and complex fluctuations — establishing that the "wobbly dynamics" the program's land-specific papers document are not an artifact of unusual modeling choices about land, but a structural possibility present in the OLG framework itself under conditions the authors show are not exotic.

The Three Results

• First: multiple steady states are possible. The simplest OLG model can have more than one steady-state equilibrium under general conditions.
• Second: multiple momentary equilibria are possible under rational expectations. At any given point in time, more than one equilibrium can be consistent with rational expectations — the mathematical precondition for the "phase transition" concept used throughout the program's land papers.
• Third: complex, non-periodic dynamics follow, but within well-defined bounds. One implication of multiple momentary equilibria is that the economy's dynamics can be marked by fluctuations that lack even regular periodicity — yet these fluctuations are not unbounded chaos; they stay within calculable ranges the authors' framework can characterize.

Relation to the Georgist Case

This paper's role in the wiki is foundational rather than directly evidentiary: it is the proof that makes the rest of the program's land-speculation results legitimate rather than special pleading. If multiplicity and wobbling required land specifically, or some unusual modeling trick, the land-speculation results would be a curiosity; this paper shows the underlying mathematical possibility is present in "the simplest of OLG models" under general conditions, which is what licenses the program's land-specific papers to treat land as channeling and amplifying a general instability rather than inventing one. Readers who want the land-specific economics should start with the flagship Henry George paper or the wobbly-dynamics land paper; this page exists so the wiki's citation of those papers can point to the general theorem underneath them.

Nuances and Limits

• No land in this paper. Included in the wiki's Hirano-Stiglitz coverage for completeness and because it is the direct theoretical foundation the land papers build on, not because it makes a land-specific claim itself.
• Abstract-level scan. Both the NBER PDF and the Oxford Academic PDF were blocked (403/Cloudflare challenge) on every fetch method tried this session; this page is built from the published abstract and search-result characterizations of the paper's three results.
• Highly technical, general-equilibrium theory. This is pure mathematical economics; it makes no empirical or policy claim on its own.

Bears On

• Research: Hirano & Stiglitz: Henry George, Land Speculation, and Economic Growth — the companion flagship paper in the same Oxford Review issue, applying this paper's general theorem to land specifically.
• Research: Hirano & Stiglitz: Land Speculation and Wobbly Dynamics — the land-and-capital application of the multiplicity result this paper proves in general.

See Also

• Joseph Stiglitz · Tomohiro Hirano
• Hirano & Stiglitz: Henry George, Land Speculation, and Economic Growth
• Hirano & Stiglitz: The Wobbly Economy

Sources

1. Tomohiro Hirano & Joseph E. Stiglitz (2025), "Overlapping generations models, multiplicity of steady states and momentary equilibria, and economic fluctuations," Oxford Review of Economic Policy 41(2): 260–290. DOI: 10.1093/oxrep/graf026 · also NBER Working Paper 34193 — abstract and search-result characterization retrieved 2026-08-18; both the NBER PDF and the Oxford Academic PDF were blocked on every fetch method tried. Used for the three-result structure (multiple steady states; multiple momentary equilibria; complex-but-bounded fluctuations), the "quite general conditions... general utility and production functions" framing, and the paper's role as the mathematical foundation for the wider research program (B-claim; abstract-level scan only).