In chapter 2 of the book we discussed the importance of weak ties. In Particular, we talked about Granovetter’s findings based on the interviews he conducted. From these discussions we then concluded that weak ties in networks are more powerful than we may think at first. A question that came to my mind after this discussion was: are weak ties always as powerful as they were for the people that Granovetter interviewed, or are they only important and powerful in some networks and not in others? In other words, is the power of weak ties a property of a network or can the context of the network change their strength?

I found a paper titled “Complex Contagions and the Weakness of Long Ties” by Michael Macy from the department of sociology at Cornell. The paper can be found in Dr. Macy’s website: http://www.people.cornell.edu/pages/mwm14/. In this paper, the authors argue than the strength of weak ties depends on what it is going to be diffused in the network. In the case of Granovetter’s jobs network, what was to be diffused was information about jobs. The reason why weak ties are so powerful in this type of network is that distant acquaintances presumably belong to a social circle different from yours. So they can provide you with information that no one else in your social circle has. This logic seems pretty reasonable as long as what is being diffused in the network is something like information. But what if it’s something else? For instance, what if we’re talking about a network in which a rumor is being diffused and we are trying to find out not what nodes have heard of the rumor, but what nodes actually believe it? Then it is probably not enough that some distant acquaintance tells a node about the rumor for the node to believe it. Before a persons starts believing a rumor she probably will hear about it multiple times. In this case, it is easy to see that the weak ties are no longer as powerful. If a person hears a rumor from an acquaintance she barely knows, and never hears about it again from her close friends it is very likely that she will forget about the rumor and never believe it. The same logic that lead us to believe that an acquaintance has access to information that no one else in a person’s social circle has, now tells us that the person will not hear the rumor from a close friend and therefore you won’t believe it. The same logic that made weak ties seem so powerful in one context makes them seem very weak in another context. In the paper, a contagion such as a rumor is referred to as a complex contagion: a behavior in which the willingness to participate may require independent affirmation or reinforcement from multiple sources. A contagion like information, or a virus is referred to as a simple contagion. The paper argues that the strength of weak ties is clear in the case of simple contagions but in the case of complex contagions they are not always as powerful.

It was very satisfying to read this paper because it answered the question I originally had. It also provided a more technical approach to justify their claims which was also very nice to see.

Based on this paper, the answer to my question is that the strength of weak ties is not a property that is present in all networks. It depends on what the network is describing. It becomes clear that it is important to be careful when trying to generalize a concept that was found by experiment to a more abstract setting. It can be easy to make serious mistakes by making models which ignore important details on how people behave.