2017 Weible and Sabatier 2017 Jenkins-Smith et al. These assumptions range from utility maximization (Rational Choice Theory) over belief systems (advocacy coalition framework), to ambiguity (multiple streams framework) (Nohrstedt and Olofsson 2016 Herweg et al. Theories of the policy process mostly originate from assumptions about the behavior of policy actors. By integrating SIPP into the analytical categories of theories of the policy process, this paper calls for a future research agenda establishing a further theoretical lens for a better understanding of policy processes. In policy subsystems, five such types appear relevant: organizational identities, local identities, sectoral identities, demographic identities, and informal identities. SIPP distinguish three levels of analysis, ranging from the psychological microlevel concerned with individual behavior and preferences, over the socio-psychological mesolevel of intra- and intergroup dynamics toward a macroperspective of general types of social identities. Additionally, social identities are moderated by internal and external factors. This salience is dependent on the strength of a social identity, determined by the feeling of belonging, positive evaluation, and emotional bond to a group.

Policy actors thus act in accordance with their salient social identity. Compared to psychological foundations of existing theories of the policy process, the social identity approach emphasizes the importance of social group membership for forming common views on policy content and shaping policy actors’ behavior as beneficial to the in-group. Drawing from the prominent and widely acknowledged psychological social identity approach, it develops the theoretical concept of social identities in the policy process (SIPP) and advances the understanding of policy actors’ behavior. This paper introduces social identity theory and self-categorization theory to policy process research.

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