COMMENTARY When is it coevolution? Giorgos Kallis ⁎ Energy and Resources Group, University of California at Berkeley, 310 Barrows Hall, Berkeley, CA 94720-3050, United States ARTICLE INFO ABSTRACT Article history: Received 11 April 2006 Received in revised form 13 December 2006 Accepted 21 December 2006 Available online 23 February 2007 This paper evaluates the differences between Norgaard's and Winder et al.'s approach to socio–environmental coevolution. Winder et al. emphasize the evolutionary dynamics of coevolutionary change. These were omnipresent in Norgaard's work but they have not been adequately explored by other ecological economists. I argue that Winder et al.'s definition of coevolution is in essence the same as Norgaard's and that their real differences are, how they see coevolution applied and how far they are willing to draw a priori a line between evolutionary and non-evolutionary socio–environmental dynamics. My thesis is that at this stage a more open approach to evolutionary dynamics and coevolution a la Norgaard is a wiser strategy than Winder et al.'s narrower approach. © 2007 Elsevier B.V. All rights reserved. Keywords: Evolution Coevolution Method Ecological Economics 1. Introduction Coevolution is a key concept in Ecological Economics (EE). Winder, McIntosh and Jeffrey (2005) opened a long-overdue debate on what we mean by coevolution in EE (Norgaard, 2005; Winder, 2005). Winder et al. attempted to sharpen the analytical boundaries of coevolution compared to Norgaard (1994). Their conclusion that coevolution should be “carefully monitored”, “constrained” and made “rare”, diverges from typical usage of the term. Norgaard (2005) challenged Winder et al. for nailing down coevolution into particular persons in the history of evolu- tionary ideas but did not address their proposal for a different approach. Winder et al. on the other hand, did not explain clearly the key reference of their approach, the so-called Darwin–Huxley synthesis, and they misrepresented Nor- gaard's work, obscuring their differences. In this paper I intend to clarify these differences. Sections 2 and 3 present briefly each approach. Section 4 identifies the goals of coevolutionary analysis. Section 5 compares and evaluates the two approaches. Section 6 concludes. 2. Coevolution a la Norgaard For Norgaard coevolution is a process of coupled change between practices, values and the biophysical environment. Humans change environments both materially and cognitive- ly, he argued, and in turn new environments change human practices and ideas. Norgaard's early work explored dynamic socio–environmental feedbacks and substitution of ecosystem by economic services. In later work Norgaard stated explicitly that coevolution is not only about “co”, but decisively, about evolution. Two systems coevolve when they have a causal impact on each ECOLOGICAL ECONOMICS 62 (2007) 1 – 6 ⁎ Tel.: +1 510 642 8779; fax: +1 510 642 1085. E-mail address: gkallis@berkeley.edu. 0921-8009/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ecolecon.2006.12.016 available at www.sciencedirect.com www.elsevier.com/locate/ecolecon