While cities have defined the way humans live and interact for millennia, social network theory (SNT) has changed the understanding of cities. SNT focuses on the interconnectivity of actors, whether on a personal or national level. Applying this theory to cities sheds light on the complexity of the urban environment.
As Sergio Rey, professor at Arizona State University, told the HPR, cities are “nodes on the network,” which are linked through any form of interaction, from something as tangible as the shipment of a good to quotidian activities like a phone call, an email, or an internet posting. Every such connection can be tracked, studied, and represented on a visual map. Seen through the lens of SNT, cities are not independent entities, but are parts of webs of interaction bound together by the interplay of physical, cultural, economic, and social ties.
Social network theory “captures the complexity and the mobility of city life in a way that a lot of other approaches do not,” Thomas Bender, professor at New York University and co-author of Urban Assemblages: How Actor-Network Theory Changes Urban Studies, told the HPR. For Bender, network theory is not a policy-oriented approach but one that is inquiry-oriented. Its primary value lies in its ability to encourage policy makers to consider the unexpected consequences of their actions on a range of potentially volatile networks.
Changes in Urban Studies
Demographic shifts have continuously change dynamics in American cities. In the 1970s, many wealthy Americans left the city centers and settled in the suburbs. Gordon Douglas, Ph.D. candidate in Sociology at the University of Chicago, explained to the HPR that the reversal of this trend in the 1990s and widening urban wealth disparity created the need for more nuanced theories to map these more complicated networks of interaction.
Michael Batty, visiting professor at the University College London, explained in a 2011 article that network theory has shifted the theoretical understanding of urban environments from thinking of “cities as machines” to “cities as organisms.” Under this view, cities grow organically by way of “preferential attachment” with each node creating links that bring in nodes from other hubs. Geraldine Pflieger, professor at the University of Geneva in Switzerland, believes that this revolution in theoretical understandings of urban areas has fundamentally changed “the way we see cities” because it has led urban scientists to take an increasingly “materialist view of the city by studying the links between the technical, political, and infrastructural and everyday experiences of the city.” Urban sociology now emphasizes the links between individual communities and the link between the local and the global.
Applications of SNT
From creating models of the spread of disease to planning public transportation systems, network theory is an important tool for city planners. The SENSEable City Lab at MIT, directed by Carlo Ratti, uses network theory techniques to create more efficient methods of organizing urban life. One product of this lab optimizes parking systems through a cost-effective scalable framework. Another presents a real-time city monitoring system using cell phone data and the location of public transportation to provide live traffic conditions.
The application of network theory to cities has revealed a phenomenon called “polycentry,” which refers to an urban environment that lacks a centralized nucleus. As Michael Hoyler, Associate Director of the Globalization and World Cities Research Network Department at Loughborough University, told the HPR, “The problem when it comes to planning such regions is that there is a mismatch between the economic geography of a polycentric region and the political geography of that region.” Network theory now allows analysts to visualize how cities may function in a larger economic network that is incongruent with their municipal limits.
In addition to geography, SNT can be used to construct complex maps of interaction of all types including financial exchange, labor exchange, migration, and traffic. Over the past decade, Holyer’s team has ranked cities by their integration into the networks of major firms, which tend to cluster in key cities. The result is an index of the global integration of cities around the world which can be used to find correlations between a city’s level of integration and other variables.
Other research projects are turning to data from Facebook and Twitter to construct maps of online interaction, with potential implications for politics. As Celine Rozenblat, professor at the University of Lausanne, explained to the HPR, these tools can be used to study political propaganda and communication. For instance, movements like Occupy Wall Street and the Arab Spring were organized with the help of social media and can also be mapped using an SNT approach.
The Future
Current studies in SNT are exploring how networks are interconnected, and determining the patterns and strengths of ties that connect communities on the national and neighborhood levels. More research remains to be done on the types of connections between various social network hubs, as well as on the processes through which social connections are formed.
Despite its utility, social network theory is not without shortcomings. For starters, Douglas believes that computerized mapping will never replace in-person ethnographic research for mapping how a living city culturally grows and changes. In addition, as Rey acknowledged, cities are highly complex entities and the task of cataloging the infinite possible uses of land within them exceeds the capabilities of existing technology.
Network theory has limited predictive power. Pflieger believes that it would be “technological determinism” to say that more interconnected cities are necessarily more homogenous or peaceful with networks less in conflict with one another. With an optimistic view, however, she views highly integrated cities as a “sort of Tower of Babel that functions well.”
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