4. Prevalent Action-Guiding Models of Scientific Expertise in Policy

Science-policy models guide the practice of the Intergovernmental Panel on Climate Change (IPCC) and other science-policy institutions. Such science-policy models are primarily about the general competence, responsibility and legitimate role of scientific experts, policymakers and other players at the science-policy interface. The central question of Part II is how well they help tackle the key challenge at the science-policy interface, i.e. help comply with the four general norms for expertise in policy (Part I)? The results of the evaluation and refinement of the predominant science-policy models will both contribute to the envisaged framework for the IPCC assessments on a more general level, and serve as useful “lenses” for the more specific evaluation of the integrated economic assessments of the IPCC (Part III). This chapter introduces the decisionist, the technocratic, the pragmatic and the legitimisation models of the role of scientific expertise in policy; these four models are prevalent in practice. Section 4.1 explains core common characteristics of these prevalent models. The systematic analysis of the four models – particularly their philosophical assumptions on scientific knowledge – as potential tools to realise the general norms for expertise in policy follows in Sect. 4.2. Finally, Sect. 4.3 explains how the analysis and evaluation of these models can be used for the evaluation of the IPCC’s work.