I liked Granovetter’s paper on “The Strength of Weak Ties” quite a bit. The concept of information diffusion gave his investigations of social networks the clarity I felt was lacking in the questions I was complaining about earlier. While information diffusion is certainly not the only perspective from which you might want to look at social networks, it is very useful for the kinds of problems Granovetter seems to be concerned with (labor markets, neighborhood coalitions, etc).
While Granovetter argues convincingly for his hypothesis that information diffuses primarily through weak ties in social networks, I found some of his starting assumptions problematic.
Granovetter defines stronger ties as ones that involve larger time commitments. Personal experience tells me that this is not the case. My family ties are stronger than my professional ties, despite the fact that I spend far more time with my co-workers than my family. Among my friends, there seems to be little correlation between time spent together and tie strength: I have very strong friends whom I see once a year or so, and “weaker” friends whom I see quite often.
Granovetter’s theory that network overlap correlates with tie strength also conflicts with the intuition that strong ties are created by shared experiences. For example, two travellers who meet overseas may form a strong bond based on their shared experiences in exotic lands. This bond may last a lifetime despite the fact that the two travellers live in different places and share no mutual friends. These kinds of stories seem to be fairly common among soldiers and expatriates.
In general, however, Granovetter’s theory coincides with my personal experience. I’ve found my most satisfying and enjoyable jobs through weak ties. And I generally find that useful information comes from people outside my immediate social group. For example, I rarely receive interesting information from my fellow SIMS students. This isn’t a reflection on them, but is a consequence of the fact that we all have many common interests, and thus I’ve usually already heard about the things I hear from them.