There is an ongoing open debate about achieving sustainable development (SD) within planetary boundaries. In this context, it is unsurprising to question the role of urban areas in speeding up an SD. The unstoppable urbanization process has been accompanied by looking at cities as places with higher economic dynamism to achieve higher human well-being. However, contemporary challenges such as tackling urban inequalities within planetary boundaries have led to a rethink of cities as a sustainable solution. In this paper, we discuss three approaches to SD: the Sustainable Development Goals (SDGs), the Doughnut Economy (DE), and Brede Welvaart adopted in the Netherlands as a feasible alternative to going Beyond GDP. We provide insights about the main overlaps and differences between these SD approaches and how they contribute to tackling urban inequalities within planetary boundaries. To do so, we consider their theoretical foundations and their translation into measurable metrics.

The theme of the conference, and the concepts used, echoes the academic study of cities as complex systems. Whether urban designers are dealing with challenges like circularity, climate adaptation or inclusion – all these topics require an understanding of complex systems. Where academics refer to scientific theories of complex systems, urban design practitioners develop implicit theories to deal with the complexity of the challenges in the urban environment. Recent discussions in the literature have not yet addressed the role of these implicit theories in urban design. This paper addresses this research gap. We propose a framework for clarifying the role of theories in urban design. This framework combines recent insights from philosophy of science and cognitive science, grounded in naturalistic realism. From this perspective, we consider theory formation as a natural human capability that occurs in various contexts. Within the framework, we view theory formation in urban design as the result of interaction between three different contexts: everyday life, professional practice, and academia. First, the framework aims to increase awareness of how theories shape our understanding of, and actions in, the urban environment and its dynamics. Second, it aims to improve the interaction between professional practice and academia by making theory formation in different contexts explicit. To illustrate the framework, we analyse the works of two Dutch urban design practices (i.e. Urhahn Urban Design and Palmbout Urban Landscapes) from the perspective of classic academic sources (i.e., Alexander and Habraken), and contemporary academic sources (i.e., Moroni and Portugali). The analysis shows that experienced practitioners develop professional theories that align significantly with scientific theories on complex systems. But also, that academics overlook more subtle theory formation in practice, shedding a new light on their calls for a radical transformation of professional practice. Likewise, experienced practitioners overlook relevant scientific findings that, at first sight, seem ‘too academic’ but are highly relevant to make their practices more explicit. Sometimes, explaining the work of experienced practitioners requires novel combinations of scientific insights. For example, by combining insights into the role of sketching and drawing to deal with the complexity of the urban environment. This paper presents a first version of a theoretical framework on theory formation in urban design, illustrated with some examples. Subsequent studies aim to further develop the framework, including more in-depth case-studies and the involvement of a larger variety of practitioners. The goal is to develop this research further to create a synergy between professional practice and academia. This can form the basis for a new generation of more theory-aware professionals that can act responsibly in dealing with future challenges.

In recent decades, there is an increasing realization that growth oriented economic models are harmful for sustained livability of our biosphere. This also holds for cities that continue to attract a growing share of the world population. The paradox of growing cities is that, while offering all kinds of social opportunities and environmental efficiencies, they tend to behave as central nodes in expanding economic networks and to destroy quality of life by rising inequalities and consumption-related pressures on ecosystems worldwide. In particular, urban patterns of economic agglomeration have been associated with more tenuous social networks and disconnection from family, social community and ecological life worlds. As such, cities both drive and receive the effects of social-ecological feedback loops, including impacts such as urban heat islands, poor air quality, risks of flooding, and increased vulnerability to global trade disruptions. To re-think the relationship between economic drivers, social relations and ecological feedback effects from an urban perspective, we propose the notion of “the nurturing city”. The word “nurturing” denotes an active attitude of caring responsibility, as opposed to one of careless consumption. This concept of nurturance emphasizes the creation of flourishing conditions for all urban inhabitants, in particular young people, as well as for the biosphere with(in) which the city co-evolves. Nurturance is its own reward, leading to a thriving population within safe limits of life sustaining ecosystems. The paper produces an emergent framework on the basis of interdisciplinary research and education activities of interdisciplinary urban economists, as an attempt to help solving the urban paradox from a plurality of perspectives.