1. Extension-généralisation des réciprocités et multilatéralisation des relationsRéciprocité indirecte Indirect reciprocity refers to general cooperative behavior within an already-established society, with an anticipated reciprocal payoff of more than just the proverbial “warm glow” in return. Drawing from the formulation of Nowak and Sigmund, indirect reciprocity can take on two forms: (i) Upstream reciprocity: First A helps B, and then B helps C (ii) Downstream reciprocity: First A helps B, and then C helps A Cible de confiance et Réciprocateur indirect Source de confiance /réciprocité indirecte Cible de confiance B C B C Cible de réciprocité indirecte Upstream reciprocity Downstream reciprocity A A Source initiale de confiance et cible de réciprocité indirecte Source initiale de confiance

2. Illustration de la réciprocité réputationnelle (qui aboutit avec lesautres formes de réciprocité indirecte à une réciprocité généralisée par la réputation) • The following example illustrates this mechanism: B owns a shop, where A shops regularly; by buying goods from B’s shop, A helps B. C sees that A shops at B’s shop, and thinks that B must provide good service and sell high-quality goods, which is why A shops there. So then C decides to also buy goods from B. Reciprocity comes into play when B implicitly helps A by providing good service and selling high-quality goods. B receives her payoff when C buys goods from B. A B C Réciprocateur indirect 2ème source de confiance Cible de confiance et De Réciprocité indirecte Source initiale de confiance