Ecosystem services economic valuation, decision-support system or advocacy?

There appears to be a discrepancy between the massive presence of Ecosystem Services (economic) Valuations (ESV) in biodiversity discourse and literature and the small number of examples where it is documented and demonstrated that they have been instrumental in changing policies. Part of this discrepancy may reflect an insufficient fit of ESV to the organizational and political dimensions of decision-making. This paper thus explores the relation between decision-making as it is viewed in the theoretical roots of ESV and also as it is depicted in disciplines that take decision as their central topic. Three alternative and complementary types of decision models (rational decision-maker, organization and political process) each shed a different light on what ESV can be useful for, and what qualities are then required of it. In general, the contribution of ESV to decision-making relies both on its ability to bring rationality to decision-making, and on its procedural qualities as resource of influence that is needed for advocacy and justification. Thus, the usefulness of ESV cannot be enhanced by either the strengthening of their rigor or the enhancement of their procedural qualities alone: to successfully address the challenge, both of these measures are required in combination. This produces a tension between the rational and substantial abilities that ESV must sustain on the one hand, and the rhetorical and procedural qualities it should develop on the other hand. To overcome this tension, it may prove useful to draw lessons from the field of policy evaluation. In this field, rationalization-based and process-based methodologies once fiercely contested each other. However, process-based and content-based methodologies are now deliberately combined in diverse designs.