The real type and ideal type of transdisciplinary processes: Part II-what constraints and obstacles do we meet in practice?

This paper builds on the theoretical foundation outlined in Part I ('The real type and ideal type of transdisciplinary processes: part I-theoretical foundations') which is included in the same special feature. Mode 2 transdisciplinarity processes are characterized as processes that relate or integrate problem-oriented interdisciplinary research with knowledge generated in a multi-stakeholder approach with the objective to develop socially robust orientations, for instance, on sustainable transitioning. In practice, transdisciplinary processes may have different functions (i.e., societal capacity building, consensus building, analytic mediation, and legitimization). Practitioners and scientists may follow different interests. And we may distinguish between different types of knowledge integration (including different perspectives, modes of thoughts or cultures). Thus, the reality of transdisciplinarity processes may become a very complex and ambitious venture whose multiple objectives are difficult to realize in practice. This paper reviews the existing challenges, obstacles, and constraints of transdisciplinary processes. This review refers to 41 mid- and large-scale transdisciplinary studies run by members of the ITdNet at seven universities on sustainable transitions of urban and regional systems, organizations, and policy processes. A comprehensive table can be used as a checklist for identifying and coping with constraints and obstacles of transdisciplinary processes in practice. The discussion identifies the main challenges for the future development of transdisciplinarity's theory and practice, including linking Mode 1 transdisciplinarity (i.e., the relating of disciplinary causation for which no interdisciplinarity is possible by merging concepts and methods) and Mode 2 transdisciplinarity, which targets sustainable knowledge and action for system transitioning