# Book Review: Six Degrees: The science of a connected age

**On:**September 24, 2007

Six Degrees: The science of a connected age

Duncan J. Watts, Norton, 2003

Duncan J. Watts (1971-) is a professor of sociology at Columbia University, head of the CDG Collective Dynamics Group and in 2003 he wrote the book Six Degrees: The Science of a Connected Age (Norton, 2003). He holds a B.Sc in physics from the University of New South Wales, and a Ph.D. in Theoretical and Applied Mechanics from Cornell University. In 1998, in conjunction with Steven Strogatz of Cornell University, Watts formalized the small world phenomenon in the celebrated Nature paper. (bron: wiki)

The title of the book is based on the Six Degrees of Separation Theory, it refers to the idea that, if a person is one “step” away from each person he or she knows and two “steps” away from each person who is known by one of the people he or she knows, then everyone is no more than six “steps” away from each person on Earth. You can find lots of links on the Internet with an interest in the Six Degrees Theory, there is even a Six Degrees Hyves.

Duncan Watts takes the reader on a journey through the science of networks and their behavior. He explains this new discipline and its origins in easy and accessible language, taking the reader on a great scientific journey. This book takes a closer look at the Six Degrees phenomenon and many other aspects and implications of it, from economic applications, epidemics, information cascades, cultural fads etc.

Watts first provides the groundwork and the theory behind the study of networks (Chapters 1-5), which introduces some basic graph theory and relations of real world networks to simple mathematical models.

Watts asks himself the following questions: “How does individual behavior aggregate to collective behavior? (24) “What makes the problem hard, and what makes complex systems complex, is that the parts making up the whole don’t sum up in any simple fashion. Rather they interact with each other, and in interacting, even quite simple components can generate bewildering behavior.”

Watts says that “at least some of the properties of extremely complicated systems can be understood without knowing anything about their detailed structure or governing rules.[…]This is a tremendously hopeful message for anyone interested in understanding the emergent behavior of complex social and economic systems like friendship networks, firms, financial markets, and even societies.” (65)

In chapters six through nine, he deals with epidemics, “the madness of crowds” and the dynamics of adaptation. He closes with views on learnings from recent crises, including the terror attacks of September 11, and with five “lessons for a connected age.”

Overall this is a very good read which I enjoyed reading. The complexity of the theory is understandable throughout the great practical examples. Watts closes with the admission that his book leaves unanswered questions, and the expectation that scientists will keep exploring the new science of networks until they get to the bottom of it … and then keep going.

“…and so it is with science – even when it seems hopeless, we struggle on, because, as with most human ambitions, it is in the struggle that we find the measure of ourselves.”(305)

“Or as Winston Churchill said after the battle of El Alamein in 1942, “This is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning.” (306)

(This book review is still in progress)