Which Theory Fits the City A Comparative Evaluation of GST, Complexity, and CAS in Addressing Urban Challenges

Urban systems are increasingly recognized as dynamic, multi-scalar networks shaped by nonlinear interactions, feedback loops, and adaptive behaviors. Addressing the “wicked problems” of rapid urbanization—from socio- economic inequality to climate risks—requires theoretical frameworks capable of capturing complexity and informing adaptive governance. This study critically and comparatively examines three major approaches— General Systems Theory (GST), Complexity Theory, and Complex Adaptive Systems (CAS)—in the context of urban systems, through a systematic literature review combined with a bibliometric analysis of publications indexed in Web of Science and Scopus between 2000 and 2025. Using bibliometrix and Biblioshiny, the analysis traces conceptual trends, keyword co-occurrence patterns, thematic clusters, author keyword distributions, and thematic evolution. Indicators such as publication growth, thematic mapping, and conceptual development provide insights into the intellectual trajectory of urban complexity research. The findings demonstrate a clear theoretical progression: GST provides a holistic framework emphasizing structural stability but has limited capacity to capture adaptive processes; Complexity Theory advances the field by foregrounding nonlinearity, self-organization, and co-evolutionary dynamics; CAS extends these perspectives by emphasizing decentralized interactions, adaptive learning, and path dependence. The bibliometric mapping shows a sharp increase in CAS-related urban studies after 2015, reflecting its growing recognition as a promising framework. Yet, this surge does not imply CAS has displaced other paradigms; planning theories, socio-spatial perspectives, and governance models remain dominant. Rather, CAS emerges as a complementary approach that enriches existing theories, clarifies theoretical boundaries, identifies research gaps, and enhances the ability to interpret and respond to complex urban transformations. This study underscores that while GST, Complexity Theory, and CAS each provide distinct contributions, CAS holds particular potential as a flexible and complementary lens for advancing both urban theory and practice.