We analyze the classic problem of sustaining trust when cheating and leaving trading partners is easy, and outside enforcement is difficult. We construct equilibria where individuals are loyal to smaller groups – communities – that allow repeated interaction. Hierarchies provide incentives...

Current open-source/peer-production technologies, such as forums, wikis and blogs, have enabled an unprecedented explosion of global knowledge sharing, but appear to be less successful at enabling collaborative deliberation (i.e. the systematic enumeration, analysis, and selection of solution...