Having finished reading both The Tipping Point by Malcolm Gladwell and Six Degrees by Duncan Watts, I'm now Tipping at Six Degrees. The topic of both books is very similar: understanding and modelling (social) networks. Many have reviewed these books, so I'll restrict myself to a few simplistic observations by reading them back-to-back.
Gladwell is a storyteller, and as Carla Verwijs correctly stated on another Gladwell book (Blink):
It's a very pleasant read and gives food for thought. All those examples, stories in fact, were fascinating. [...] I miss concrete guidelines what to do next.
Watts, in contrast, tells a personal story trying to understand how to model (social) networks and explains what worked and what does not. Whereas Gladwell, a journalist, makes you believe that a story contains some truth with wide applicability, Watts shows that even traditional wisdom can be incorrect when applied to social networks. My overall feeling after reading both books is that modelling social networks is an enormous challenge (I already knew that :-)).
There is a huge overlap in the examples used in both books (which is slightly suspicious). One striking example were Gladwell provides the story and Watts the explanation is the following. A person is mugged and tens of people see it from their window, nobody phones the police (Gladwell). He explains this by stating that all witnesses thought somebody else would phone the police. Watts, although he does not use this example, has an explanation with some mathematical foundation. The general notion, intuitively correct, that news travel faster when more people know it, is false. When everybody in a social context knows it, there is no point in forwarding it. And this is precisely what makes social networks different from physical networks. Social beings can think along multiple dimensions: the content of the message and the impact of the message. If a human thinks the receiver already knows it, there is no point in transmitting the message, however valuable it may be.
What did I learn from reading these books? Quite a lot. Gladwell's stories may seem entertaining, knowing them is an asset that can come in handy (both socially and scientifically). Watt's experience as a scientist is somewhat similar to what I experienced when thinking about weblog communities, and, being an optimist, I hope that my notes while reading it will at some point in the future turn out to be valuable.