Emergence

In Everything is Obvious, Duncan J. Watts briefly mentions ‘emergence’ in the context of sociology’s micro-macro problem: explaining ‘macro’ phenomena involving large numbers of people that are driven by the ‘micro’ actions of individuals, each making rational choices. Emergent complexity has been first observed in natural sciences, where the laws governing a higher scale of a phenomenon cannot be derived from laws that apply at a lower scale. Watt gives the example of particle physics being pretty much useless to explain the chemistry of synapses. Social phenomena, however, are characterized by an extremely high level of complexity, making them perhaps the hardest to study in the context of emergence.

For an introductory overview of emergent behavior, see this PBS documentary on emergence and a brief demonstration of emergent behavior in birds (flocking).