Strength of Weak Ties

The concept of the “strength of weak ties” was first proposed and developed by Mark Granovetter in a 1973 article of the same title. The argument is that while one might think strong interpersonal ties are more significant than weak for most purposes, this may not be so when what people need is information. Because our close friends tend to move in the same circles that we do, the information they receive overlaps considerably with what we already know. Acquaintances, by contrast, know people that we do not, and thus receive more novel information. This is in part because acquaintances are typically less similar to one another than close friends and in part because they spend less time together. Moving in different circles from ours, they connect us to a wider world. They may therefore be better sources when we need to go beyond what our own group knows, as in finding a new job or obtaining a scarce service. This is so even though close friends may be more interested than acquaintances in helping us; social structure dominates motivation.

This argument also has macrolevel implications. If each person's close friends know one another, they form a close-knit clique. This suggests that individuals are connected to other cliques through their weak ties and not their strong ones. Thus, from an “aerial” view of social networks, cliques are connected to one another, if at all, mainly by weak ties. It is, then, weak ties that determine the extent of information diffusion in large-scale social structures (playing, in this regard, a role similar to that of hydrogen bonds in chemical reactions). One outcome of this is that in scientific fields, new information and ideas are more efficiently diffused through weak ties (see Granovetter 1983). Another application is to community organization. Granovetter (1973) argued that communities lacking in weak ties may be fragmented into discrete cliques that have great difficulty organizing across these to confront a common threat. See, for example, his comments on the inability of some communities to resist destruction brought by “urban renewal” (pp. 1373–76) and his exchange with Herbert Gans (Granovetter 1974) who had proposed a more cultural argument to explain the same phenomenon.

Though Granovetter was the first to develop the sociological implications of this argument in detail, he drew on earlier research that strongly suggested this effect. For example, Rapoport and Horvath (1961) had shown that if you ask junior high school students to name their eight best friends in order, best, next best, and so on, and you then trace out networks of all those reached from randomly chosen starting points, considerably more people can be reached through seventh and eighth best friends than through first and second best. They attributed this to the greater overlap of networks among closer friends.

Later work has extended these arguments. Granovetter (1983) reviewed a series of studies that used or assessed the validity of the weak ties idea. Marsden and Campbell (1984) made the first serious attempt to assess the validity of different measures of tie strength, concluding that “closeness” or “emotional intensity” was a better indicator than three others Granovetter had mentioned in his original article—amount of time spent together, reciprocal services, and mutual confiding. Burt (1992) extended the weak ties argument by emphasizing the importance of “structural holes” in social networks. His approach emphasizes the importance of whether ties bridge separate parts of social networks and the strategic advantage for those who can operate through those bridging ties and thus control the only route for important information or resources to flow from one segment to another. Beginning in the late 1990s, the idea of weak ties became one part of a new interdisciplinary literature on complex networks, which developed more sophisticated arguments than before on flows, connectivity, and the robustness or fragility of large networks, including metabolic reactions in biochemistry, systems of electric power distribution, and the World Wide Web (see Barabasi 2002; Buchanan 2002; Watts 2003).

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