Commitment is the glue holding together characteristically human forms of social life. Commitments make individuals' behavior predictable in the face of fluctuations in their desires and interests, thereby facilitating the planning and coordination of joint actions involving multiple agents. Moreover, commitments make people willing to perform actions that they would not otherwise perform. For example, a taxi driver picks up his clients and transports them to their desired destination because they are committed to paying him afterwards for the service, and a construction worker performs her job every day because her employer has made a credible commitment to pay her at the end of the month. Indeed, the taxi driver and the construction worker are willing to accept money as payment only because a network of other agents (notably the central bank) is committed to taking various measures to sustain the currency in question. Thus, social objects and institutions such as jobs, money, government, scientific collaborations and marriage depend for their origin and stability upon the credibility of commitments.