Steven Johnson: Emergence, Simon & Schuster 2001

This excellent book investigates the concept of emergence lucidly and in terms of lively examples.  The aim is to unearth the "secret history of decentralized thinking" (p. 17) and "the unknown science of self-organization" (p. 18), by bringing together insights and results from a whole range of seemingly unrelated disciplines and fields of study all of which bear on the "movement from low-level rules to higher-level sopistication" (p. 18), i.e. "what we call emergence".

One theme Johnson studies with particular  force is cities as structures with a life of their own. Drawing from the groundbreaking ideas of Jane Jacobs, Johnson stresses the significance of sidewalks for the emergence of the creativity of a city and its life-form. Sidewalks pay off on the micro level but even more at the macro level - in ways that cannot really be explained or predicted from the micro level. "The value of the exchange between strangers lies in what it does for the superorganism of the city, not in what it does for the strangers themselves." (p. 96) "Sidewalks work because they permit local interactions to create global order." Thus Johnson makes the case for cities as structures that learn, find ways to be more adaptive.

This same basic logic of emergence is further illustrated by Johnson with an illuminating discussion of ant colonies (which manage to create their superbly impressive and adaptive structure without any central command), of living cells in our body working together, and of software and videogames.

Johnson identifies four core principles in the study of emergence: neighbor interaction, pattern recognition, feedback, and indirect control (p. 22), each of which he discusses separately and with insight. I find Johnson's discussion extremely useful personally, not only for general intellectual reasons, but also because my conviction is that his four principles of emergence play a key role in what we have called systems intelligence - and in the kind of positive philosophy of life which I believe in.