Ce mardi au GAEL : Nicolas Pasquier, Chargé de recherche INRAE

From first to second layer of uncertainty: How ambiguity shapes contributions in threshold public goods games 
 

Mardi 14 octobre 2025, Nicolas Pasquier et Pascal Toquebeuf
 

Résumé : Various collective action problems can be modeled as threshold public goods games: a public good is provided only when total contributions exceed a threshold. In practice, the threshold is often uncertain, as one or more models may offer differing predictions of its true value. We compare equilibrium contributions in settings with a single model (capturing only risk) to situations with multiple models, introducing model uncertainty—a second layer of uncertainty stemming from ambiguity about which model to rely on. Our results contrast with existing literature: (i) when contribution costs are sufficiently low, second-layer ambiguity increases contributions compared to settings with first-layer ambiguity, and (ii) second-layer ambiguity aversion induces a ratchet effect, whereby a minimum level of contributions is maintained even as costs rise. These findings highlight how second-layer ambiguity and ambiguity attitudes influence cooperation in public goods games. 
 

Le séminaire a lieu à 13h00 en salle 227.