Weak ties are more likely to be bridges to new networks
Granovetter’s original article distinguishes between regular network paths and “bridges.” All networks contain paths that connect between nodes. A path becomes a bridge when it is the only one that connects a specific node to another. Bridges are particularly important for networks because they connect spheres of information that would otherwise not speak to each other. For example, a bridge might be a medical doctor whose brother is a lawyer and who can connect doctors to the legal world when the need arises. Or a bridge might be a U.S. government official with personal contacts in a foreign country and who can facilitate cross-country communication on sensitive policy issues.
Bridges are key to information transfer in networks. Without them, networks become debilitated. The more bridges a network has, the faster information can flow through it. Moreover, a network with many bridges is likely to have access to more diverse information.
Granovetter suggests that weak ties are far more likely to be bridges in a network than strong ties. This is because your strong ties — the people you know well — are also likely to know each other well. This means that there would be numerous paths from you to any one of your close contacts. Thus, none of your strong ties is likely to be a bridge to another network. In contrast, weak ties are more likely to be connected to networks you do not know, and so they are much more likely to be bridges.
weak ties are more likely to be connected to networks you do not know, and so they are much more likely to be bridges
The power of weak ties is well settled with data
The data Granovetter brings forth in his 1973 article are illustrative in helping us see the importance of weak ties. He cites the ingenious studies done by psychologist Stanley Milgram that tested whether we live in a “small world.” A participant in the study was given a booklet that he or she must then pass on to some randomly chosen person in the U.S. through referrals and mutual acquaintances. The study found that the proportion of successful deliveries ranged between 12% and 33%, and the number of links in the chain ranged from 2 to 10. But more importantly, the study also found that sending the booklet to an acquaintance made it more likely that it would eventually be delivered to the right recipient compared to sending the booklet to a friend. This teaches us that connecting with weak ties enabled networks to be more successful.
Another illustrative study that Granovetter cites was done by sociologists Rapoport and Horvath in 1961. Students in a Michigan junior high school were asked to rank their 8 best friends. The researchers created a network from the persons listed at the highest rankings and another network from the persons listed at the lowest rankings. The results were clear: The network created from all the best friends was much smaller than the network created from the acquaintances. The aggregation of weak ties led to a much larger network than the aggregation of small ties.