The theoretical foundation of what we call (spatial) planning sciences or studies is difficult to grasp. Even researchers in the field of planning disagree on what is meant by a planning theory, by the core of planning or by the subject of planning sciences (e.g. Friedmann 1998, Forester 1989). Seminal writings around planning theory include Faludi’s Reader in Planning Theory (1973) highlighting the procedural aspects of town planning ideology, and the practice of ‘muddling through’. Fainstein in her various contributions (e. g. in 2000) discusses the interlinkages between urban theory and planning theory by focussing on the communicative planning model, new urbanism, and the implications of planning for a just society through bottom-up participatory approaches. Ultimately, most of these academic debates are concerned with the planner’s role in the process of planning. Yet, it is interesting to observe that most of these writings around Planning Theory are Readers in Planning Theory (Faludi in 1973, Fainstein in 2016, Wiechman in 2019), or bring together different theoretical lenses that may be relevant for parts of planning processes (Gunder et al. 2017, Allmendinger & Tewdwr-Jones 2002) or provide an overview of approaches to planning for teaching purposes (Allmendinger 2009, 2017), but do not outline what a planning theory constitutes of and what lies beyond procedural aspects.

If one considers (planning) sciences in general as knowledge foundation of the profession in which planning actions are reflected, analysed, discussed and modified, this missing theoretical foundation leads to a multitude of problems – for researchers in spatial planning, for planners in practice and for scientific institutions. The lack of clear explicit understandings of spatial planning, its foundations and theoretical core aspects leads to insufficient clarifications of the arguments in the academic debate itself and, in the worst case, fundamental incomprehension. Practitioners in the field of planning, however, hardly benefit from contemporary planning theories, resembling ideal-typical reflections on planning processes far off everyday challenges. However, this weakness of planning sciences is becoming increasingly noticeable for scientific institutions such as universities, colleges and academies as well: Academic planning institutions struggle to compete for scientific excellence under the condition of quality standards and evaluation criteria. They face sweeping obligations to justify planning’s interdisciplinary approach, its knowledge foundations and its scientific nature. In sum, planning sciences hardly provide researchers and practitioners with sufficient knowledge to improve both theories and practices.

In the academic discussion, a debate about substantial foundations of planning, knowledge specific to planning subjects as well as the scientific perspectives of planning is hardly ever held. This is the starting point of the suggested International Working Group.

The International Working Group aims to provide a platform for setting planning sciences on the move, through innovative debates about the challenges, barriers and necessities to rethink planning sciences, its origins and characteristics. A crucial challenge is to focus on those issues that are of direct relevance to spatial planning as scientific activity.

This implies to rethink

• what spatial planning is and what is meant by planning,
• what the paradigmatic foundations of planning sciences/ studies are and the impact they have on planning research and practice,
• what distinguishes planning approaches from conceptions, models and theories in and especially of planning,
• about the theoretical linkages and complementarities with other sciences and their theoretical foundations
• about quality standards of an interdisciplinary research without neglecting disciplinary origins
• or the role of space in planning sciences.

Thereby we do not seek to reduce planning to one universal understanding or to develop one overarching planning theory – in contrast, it is the crucial challenge to build a complex puzzle of what planning might be and elaborate on a contemporary understanding of planning sciences in the 21st century. Further, it shall encourage scholars to make space for theoretical furthering of ‘planning’ itself.