During the last decades, environmental economics as a science has been very successful in improving our understanding of environment-economy interdepen dence. Using conventional economic methodology, environmental aspects have been explicitly incorporated into economic models making use of the concept of externality. This concept was already familiar to economists long before evidence of severe environmental deterioration found its way into the headlines and peo ple's awareness. But before that time, external effects were not considered as being empirically very relevant, they seemed to be...