Microtheory Seminar Series. Robust Social Discounting under Expert Disagreement
Published: 9 February 2026
10 March 2026. Professor Philippe Bich, Paris School of Economics (PSE)
Professor Philippe Bich, Paris School of Economics
"Robust Social Discounting under Expert Disagreement"
Tuesday, 10th of March. 16:00
Room 383 ASBS
Abstract
How should a policymaker choose a discount rate when experts disagree not because some are mistaken, but because they hold different values? We propose a theory of robust social discounting. We model expert recommendations as draws from a distribution and fit this to survey data. Rates where the fitted density is high are considered more plausible; rates where it is low are considered less plausible but not ruled out. Policies are evaluated by balancing caution and evidence: the policymaker focuses on the discount rate that minimizes welfare, but penalizes the use of rates that contradict expert opinion. Our key behavioral axiom, Invariance to Delayed Improvement, requires that welfare improvements remain improvements when delayed; it uniquely characterizes the robust representation. The framework implies policy-dependent discount rates: rising benefit streams activate high rates, declining streams activate low rates. The Stern–Nordhaus divide is thus reframed—their rates emerge as worst cases for different policy profiles, not competing prescriptions.
Bio
Position at Université Paris Dauphine from 2000 to 2005. Associate Professor (Maître de conférence) at University Paris 1 Panthéon Sorbonne from 2005 to 2012. Full Professor at Université Paris 1 Panthéon Sorbonne since 2012 (exceptional class since 2023).
Associate member of the Paris School of Economics. Director of Master 2 program MMMEF (https://mmmef2022-2023.weebly.com/). Member of the executive board of doctoral school ED465 (Economics, mathematics, sociology) and representative for doctors studies in Mathematics at University Paris 1 Panthéon Sorbonne.
Current teaching: Fixed-point theory (M2), Optimization (M1), Game theory (M2).
Personal webpage: https://bichgame.wordpress.com/
Research fields: Economic theory, game theory, Network formation and network games, Decision theory and aggregation, inequality measurements, fixed-point theory, discontinuous games.
Many of his earlier research contributions are related to general equilibrium with incomplete markets, fixed‑point theory, and discontinuities.
For further information, please contact business-seminar-series@glasgow.ac.uk.
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First published: 9 February 2026