This lecture reviews the literature on the voluntary contributions to public goods by repeatedly-interacting contributors and discusses how the economic theory of choice of sequences of actions sheds light on the outcomes of voluntarism. Professor Long will draw attention to abstract public goods, such as the stock of mutual trust in a community, and the building up of a spirit of cooperation. Game-strategic aspects of voluntary contributions are also discussed, including the role of behavioural norms, the selection of contribution strategies, and coordination problems. Applications of line of research range from foreign aid to memberships in international environmental agreements.
