We analyze efficient risk-sharing arrangements when coalitions may deviate. Coalitions form to insure against idiosyncratic income risk. Self-enforcing contracts for both the original coalition and any deviating coalition rely on a belief in future cooperation which we term \social capital". We...

We analyze efficient risk-sharing arrangements when the value from deviating is determined endogenously by another risk sharing arrangement. Coalitions form to insure against idiosyncratic income risk. Self-enforcing contracts for both the original coalition and any coalition formed (joined)...

In this article, I discuss the role a progressive income tax system and a redistributive pay as you go (PAYGO) social security system can play in insuring and reallocating idiosyncratic as well as aggregate risk. I also argue that the underlying source of market failures generating such a role...