Myerson & Satterthwaite (1983): Efficient Mechanisms for Bilateral Trading

Summary

"Efficient Mechanisms for Bilateral Trading" is a 1983 article by Roger B. Myerson and Mark A. Satterthwaite, published in the Journal of Economic Theory, vol. 29, no. 2, pp. 265–281.[1] The paper studies bargaining between one buyer and one seller for a single object, where each side's valuation is a private, independently drawn random variable unknown to the other. Its abstract states the central result directly: the authors "characterize the set of allocation mechanisms that are Bayesian incentive compatible and individually rational, and show the general impossibility of ex post efficient mechanisms without outside subsidies."[1] This impossibility result is now known as the Myerson–Satterthwaite theorem.

The Core Result

Under incomplete information about each party's true valuation, no trading mechanism can simultaneously guarantee: (1) an efficient outcome (trade happens whenever the buyer values the object more than the seller), (2) that honest revelation of valuations is each party's optimal strategy (Bayesian incentive compatibility), (3) that neither party is ever made worse off by participating (individual rationality), and (4) that the mechanism is self-financing, requiring no subsidy from an outside party — whenever there is a positive probability that trade is efficient for some valuations but not others (i.e., the buyer's and seller's valuation ranges overlap).[1] The paper also shows, for a wide class of problems, how to compute mechanisms that maximize expected total gains from trade or a broker's expected profit, and demonstrates that under symmetric uniform priors, a bargaining game studied earlier by Chatterjee and Samuelson achieves the maximal expected gains from trade obtainable under these constraints.[1]

Relevance to the Georgist Case

The theorem is cited in Eric Posner and Glen Weyl's Radical Markets (Ch. 1, footnote) as a formal argument that private, unassisted bargaining cannot be relied upon to achieve efficient trades whenever the parties have private information about their own valuations — a direct qualification of the informal "Coase theorem" intuition that parties will generally bargain their way to an efficient outcome absent transaction costs.[2] This matters for the Georgist holdout problem in land assembly: when an assembler needs many parcels from separate owners who each have private reservation prices, ordinary sequential bargaining is exactly the kind of bilateral-trade setting the theorem covers, and owners face a structural incentive to misrepresent their true valuations rather than reveal them honestly. This is part of the motivation for mechanism-design alternatives such as the Clarke-mechanism and self-assessment proposals analyzed in Tideman & Plassmann's land-assembly paper, and for self-assessed-value taxation schemes like the Harberger tax.

Limits and Caveats

The theorem is a general impossibility result about bilateral trade (one buyer, one seller) under private information; it does not by itself say anything about multilateral land-assembly bargaining with many owners, nor does it establish that any particular real-world land negotiation fails to reach efficiency — it establishes only that no mechanism can be guaranteed to succeed across the full range of possible private valuations. It is a piece of formal bargaining theory adopted into the Georgist argument by analogy to the land-assembly setting, not a result derived from or tested against land markets specifically. The multilateral extension has, however, been made explicitly: Kominers and Weyl (2012) show that a Myerson–Satterthwaite-type impossibility carries over to the assembly of complements from many private sellers — "[h]oldout problems prevent private (voluntary and self-financing) assembly of complementary goods—such as land or dispersed spectrum—from many self-interested sellers"[3] — so that no voluntary, self-financing, individually rational mechanism can be guaranteed to assemble the parcels efficiently. That result is the formal multi-owner analogue of the bilateral theorem, and (being co-authored by Weyl) is a direct bridge between this impossibility literature and the Radical Markets proposals.

See Also

• Holdout Problem (Land Assembly) — the land-specific bargaining failure this theorem's logic is cited to motivate
• Radical Markets — the discovery-source book citing this paper against Coasean private-bargaining solutions
• Ronald Coase — originator of the private-bargaining intuition this theorem formally qualifies
• Providing Incentives for Efficient Land Assembly — a mechanism-design response to the holdout problem in the same tradition

Sources

1. Roger B. Myerson & Mark A. Satterthwaite (1983), "Efficient Mechanisms for Bilateral Trading," Journal of Economic Theory 29(2), 265–281. Open-access PDF: cs.princeton.edu/courses/archive/spr10/cos444/papers/myerson_satterthwaite83.pdf — verified verbatim this session (abstract and Theorem 1 statement) — used for the abstract's statement of the impossibility result, the model setup (single buyer/seller, private independent valuations), and the paper's additional results on gains-from-trade-maximizing mechanisms.
2. Eric Posner & Glen Weyl (2018), Radical Markets: Uprooting Capitalism and Democracy for a Just Society, Princeton University Press, Ch. 1. Publisher — discovery source book; cited (per this wiki's discovery notes) as invoking Myerson-Satterthwaite against Coasean assumptions about costless private bargaining.
3. Scott Duke Kominers & E. Glen Weyl (2012), "Holdout in the Assembly of Complements: A Problem for Market Design," American Economic Review 102(3), 360–365. DOI: 10.1257/aer.102.3.360 · free PDF — used for the formal extension of the Myerson–Satterthwaite-type impossibility from bilateral trade to multi-seller assembly of complements (land, spectrum); abstract sentence quoted verbatim from the freely available PDF.

[VERIFY: item 2's exact footnote wording and page in Radical Markets was not directly re-read this session; the citation is carried from this wiki's existing discovery-report notes on the book. A future revision should confirm the precise footnote text against the source directly.]