Special Issue the Human Actor in Ecological-economic Models Preface

Changing current consumption and production patterns into a more sustainable pathway requires explicit inclusion of behavioural aspects of the human actor. However, human behaviour is one of the most complex phenomena of analysis. The various disciplines studying human behaviour, like economics, sociology, anthropology and psychology, are rather fragmented, offering distinct theories for every topic. A frequently used tool for analysis of ecological economic systems is the formal mathematical model. Actually, the use of formal models is mainly restricted to mainstream economics. These models are useful for the consistent analysis of relations between human activities and consequences for the environment. However, when formal models are developed, not every nuance of our limited understanding can be included. In recent years a number of promising developments took place in various fields that are involved in modelling human behaviour in relation to environmental problems. Briefly, these developments are: (1) the recognition by ecologists that the analysis of ecosystems requires the explicit inclusion of human activities, (2) the increasing recognition within economics of the limits of the rigid rational actor, and (3) the emergence of new mathematical and software tools that facilitated the use of simulation models by social scientists. Ecological science traditionally studies ecosystems. Recently, an increasing number of ecologists argue that ecosystems cannot be studied anymore in isolation (Gunderson et al., 1995, 2000). Human activities have impacts on every ecosystem all over the world. Even ecosystems in relatively isolated parts of the world, like the arctic regions, contain toxic particles and are affected by stratospheric ozone depletion and possible climate change. Furthermore, due to the increasing pressure of population growth and the resulting economic activities, conflicts between human needs and ecosystem values lead to a need for integrated analysis of ecosystems and human activities. New streams of science, like ecosystem management and political ecology, explicitly focus on the integrated analysis of man and the environment. Traditionally, economics is the social science in which many formal models of human behaviour have been designed. Conventional economic theory makes use of rational actors, the Homo economicus, to study human behaviour. The rational actors are self-regarding individuals maximising their own well-being. However, the powerful concept of the rational actor seems to be invalid according to experimental research in economics and psychology (Thaler, 1994; Loomes, 1998). Deliberation about an economic decision is a costly activity in terms of time and cognitive effort, and many social scientists argue that peo-