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Efficiency and Equilibrium when Preferences are Time-Inconsistent


  • Erzo G J Luttmer
  • Thomas Mariotti


We consider an exchange economy with time-inconsistent consumers whose preferences are additively separable. When these consumers trade in a sequence of markets, their time-inconsistency may introduce a non-convexity that gives them an incentive to trade lotteries. If there are many consumers, competitive equilibria with and without lotteries exist. The existence of symmetric equilibria may require lotteries. Symmetric equilibria that do not require lotteries are generically locally unique. Allocations that are Pareto efficient at the initial date are also renegotiation-proof. Competitive equilibria are Pareto efficient in this sense, and for generic endowments, if and only if preferences are locally homothetic. For non-homothetic preferences, the introduction of lottery markets has an ambiguous impact on the equilibrium welfare of consumers at the initial date.

Suggested Citation

  • Erzo G J Luttmer & Thomas Mariotti, 2003. "Efficiency and Equilibrium when Preferences are Time-Inconsistent," STICERD - Theoretical Economics Paper Series 446, Suntory and Toyota International Centres for Economics and Related Disciplines, LSE.
  • Handle: RePEc:cep:stitep:446

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    Cited by:

    1. Kihlstrom, Richard, 2009. "Risk aversion and the elasticity of substitution in general dynamic portfolio theory: Consistent planning by forward looking, expected utility maximizing investors," Journal of Mathematical Economics, Elsevier, vol. 45(9-10), pages 634-663, September.
    2. Tommaso Gabrieli & Sayantan Ghosal, 2013. "Non-existence of competitive equilibria with dynamically inconsistent preferences," Economic Theory, Springer;Society for the Advancement of Economic Theory (SAET), vol. 52(1), pages 299-313, January.
    3. Andersen, Torben M. & Bhattacharya, Joydeep, 2016. "Why mandate young borrowers to contribute to their retirement accounts?," ISU General Staff Papers 201609260700001016, Iowa State University, Department of Economics.
    4. Bernes Karaçay & Murat Yýmaz, 2016. "A Dynamic Investment Model under Time-Inconsistency," Bogazici Journal, Review of Social, Economic and Administrative Studies, Bogazici University, Department of Economics, vol. 30(1), pages 23-49.
    5. Dziewulski, Paweł, 2015. "Efficiency of competitive equilibria in economies with time-dependent preferences," Journal of Economic Theory, Elsevier, vol. 159(PA), pages 311-325.
    6. Chatterjee, Satyajit & Eyigungor, Burcu, 2016. "Continuous Markov equilibria with quasi-geometric discounting," Journal of Economic Theory, Elsevier, vol. 163(C), pages 467-494.
    7. Ambec, Stefan & Treich, Nicolas, 2007. "Roscas as financial agreements to cope with self-control problems," Journal of Development Economics, Elsevier, vol. 82(1), pages 120-137, January.

    More about this item


    Dynamic inconsistency; competitive equilibrium; lotteries; generic inefficiency.;

    JEL classification:

    • D91 - Microeconomics - - Micro-Based Behavioral Economics - - - Role and Effects of Psychological, Emotional, Social, and Cognitive Factors on Decision Making
    • D50 - Microeconomics - - General Equilibrium and Disequilibrium - - - General

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