We construct a tractable ‘fundamental’ model of money with equilibrium heterogeneity in money balances and prices. We do so by considering randomized monetary trades in a standard search-theoretic model of money where agents can hold multiple units of indivisible ‘tokens’ and can offer...

According to theory, money supports trade in a world without enforcement and, in particular, in large societies, where gift-exchange is unsustainable. It is demonstrated that, in fact, monetary equilibrium breaks down in the absence of adequate enforcement institutions and it collapses as...

What institutions can sustain cooperation in groups of strangers? Here we study the role of monetary systems. In an experiment, subjects sometimes needed help and sometimes could incur a cost to help an anonymous counterpart. In the absence of money, the intertemporal exchange of help, which...

We study cooperation in economies of indefinite duration. Participants faced a sequence of prisonerʼs dilemmas with anonymous opponents. We identify and characterize the strategies employed at the individual level. We report that (i) grim trigger does not describe well individual play and there...