When economists and ecologists meet on Ecological Economics: two science paths around two interdisciplinary concepts

Ecological economics essentially grew out of economists working in the environmental field and growing dissatisfied with the way that standard economics saw interactions between nature and societies and ecologists anxious to take human activities (including economic) into account in a much more direct way, within the dynamic of the ecosystems on which they depend. This clearly inscribed the new field of ecological economics within an interdisciplinary and even transdisciplinary perspective. In order to try to provide some thoughts on the evolution of this trend and the relationship between economists and ecologists, we have chosen to focus on two items 1 that are undoubtedly among the achievements of ecological economics, although their mobilization is far from uniform among the authors who make use of them: coevolution and ecosystem services. In order to do so, the itinerary of two authors recognized in the field of ecological economics will be examined: Richard B. Norgaard, whose work on the coevolutionary paradigm (Norgaard, 1994) is recognized as one of the foundations of ecological economics (Munda, 1997); Robert Costanza, who initiated work on the monetary valuation of ecosystem services 1 For the moment, we would like to use the generic term for the subject. We shall see later that these subjects may be alternatively (and often also simultaneously) used as metaphors, concepts, and instruments of public policy. 2 (Costanza et al., 1997) that is a marker in the field of ecological economics. What unites these two authors is a manifest interest in the work coming out of systems analysis in the 1970s-as we shall see, that interest ultimately led to fairly contrasting visions of the field of ecological economics.