Let a large-number of small-individuals contribute to charity. We show that ‘strong aggregate complementarity’ is necessary for multiple equilibria in a competitive equilibrium. Consider two equilibria with low (L) and high (H) levels of giving. Suppose that society is stuck at L and wishes...

Consider a large number of small individuals contributing to a charity or to a public good. We study the properties of a competitive equilibrium in giving and allow for multiple equilibria. Our proposed condition, aggregate strategic complementarity, is a necessary condition for multiple...

In a competitive-equilibrium analysis of giving to charity, we show that strategic complementarity between individual giving and aggregate giving can lead to multiple equilibria. This provides a possible explanation for observed heterogeneity in giving. It is possible, but not necessary, that at...

We focus on an “equilibrium analysis” of coordination problems in giving that lead to multiple equilibria; the notion of strategic complements and substitutes turns out to be useful in this regard. Some societies can get stuck at a low level of giving while others might, by accident or...