Weak Ties: The Urban History of an Algorithm
Networks and Society
Whether it is online or in our daily physical routines, we interact with others—close friends, acquaintances, familiar and unfamiliar strangers—in ways that over time come to show patterns. Network theory represents these relationships as graphs, using the visual language of ties (lines) connecting nodes (circles) to describe the topography and dynamics of families, friendship groups, workplaces, neighborhoods, and communities. By representing complex systems as graphs, network science allows us to link micro and macro phenomena: to understand how ideas and things are transmitted and disseminated, or travel and spread.
Since it was first theorized in 1973 by economic sociologist Mark Granovetter, the concept of “weak ties” (connections between acquaintances) rather than “strong ties” (connections between friends) has been foundational to understanding how information and influence travels within networks. The concept is central to current social media sites such as LinkedIn, a professional networking platform with more than 690 million users, which cultivates and capitalizes on weak ties to help users find jobs. They are also key to seemingly more intimate sites: Facebook, for instance, which describes users as “friends,” has used an analysis of weak ties to explain how its users gain novel information from contacts with whom they do not often interact.
Granovetter’s hypothesis of the “strength of weak ties,” like other central network science concepts such as homophily, drew from ethnographic studies within mid-century urban sociology. If homophily, the idea that similarity breeds connection, underlies the polarization that occurs in many online networks, weak ties can be used to combat polarization and acknowledge—even activate—the fact that we live in a world of difference. Weak ties offer a way to engage the rich ambivalence that pervades everyday interactions with acquaintances.
Micro Connections, Macro Phenomena
In “The Strength of Weak Ties,” Mark Granovetter argued that weak ties are paradoxically strong because they connect disparate individuals and communities. His positive evaluation challenged the conventional wisdom about “good” ties within networks and positive social relationships in cities. At the time Granovetter was writing, the prevailing scholarship in urban sociology had viewed weak ties as evidence of social alienation in cities. Drawing from this, researchers developed models that assessed the importance of nodes according to their centrality, that is, the number of ties they had. In contesting this line of thought, Granovetter not only overturned standard ways of measuring the social health of communities, but also emphasized quality over quantity of information. He argued that “novel” information—news not already known within one’s group of closest friends—was most useful during critical moments, from looking for a job to organizing for political action.
Granovetter used four factors to determine the strength of social ties: the “amount of time, the emotional intensity, the intimacy (mutual confiding), and the reciprocal services.” A weak tie therefore is not intense, nor intimate, nor reciprocal, and this, Granovetter argued, perversely makes them valuable in that they tend to “bridge” individuals or groups who are dissimilar. Bridges, he argued, are ties that cross different clusters in a network and serve as the only…
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