The paper discusses and redefines the traditional concept of externalities. Inspired by J.R. Commons' theory of institutional evolution we define externalities as policy relevant institutional interdependencies. Our concept of externalities is more general and reflects institutional failure...

The paper analyzes the exploitation of a local common where the behavior is steered by altruism rooted in social norms. The analysis is illustrated by using the Gordon-Schäfer model of a fishery. We start by reviewing the standard results when all exploiters are purely egoists; i.e., when own...

The paper analyzes the conflict between illegal and legal exploitation of wildlife species in an East African context. In the model there are two agents, an agency managing a national park of fixed area and a group of local people living in the vicinity of the park. The park agency has the legal...