The importance of complexity for the research agenda in the built environment

Traditionally, science has attempted to understand urban systems using a reductionist approach in which the behaviour of a system (city or region) is represented as being an equilibrium mechanical interaction of its components. These components are either 'representative agents' for the different categories of supply and demand that inhabit the system, or the buildings and transport links that they create. This equilibrium assumption views their spatial distribution as optimal and stationary. Over recent decades, attempts have been made to introduce more dynamic approaches, in which equilibrium is not assumed, and there are many models and methods that try to do this. However, this still denies the essential complexity of the urban or regional system in which activities, natural endowments, culture, skills, education, health, transport, house prices and the global economy all combine to affect the evolution of the system. Just as in ecology, the key to the survival of cities and regions is the diversity, and innovative and adaptive power of people and society to counter new difficulties and create new opportunities. This fluid, adaptive power is a product of the complex system and can only be modelled and anticipated to a limited degree. However, cities and regions can limit the possibility of successful adaptation if they are too well-organized or too unimaginative. New models of adaptive organization allow us to understand better the need for integrated views linking land-use changes to environmental, socio-economic and cultural factors. These provide a new, more open way of considering the importance of adaptable, emergent networks, and the need for multiple and burgeoning accessibility to others.