ABSTRACT
Many of our most troubling long-range problems—trade balances, sustain-ability, AIDS, genetic defects, mental health, computer viruses—center on certain systems of extraordinary complexity. Despite appearances, the systems have enough significant characteristics in common to make it possible, even probable, that common general principles explain their dynamics. For this reason, the chapter aims to group these systems under a single classification at the Santa Fe Institute, calling them complex adaptive systems (CAS). The combination of internal models with a diversity of agents, along with the attendant nonlinearities, undercuts most traditional approaches to system dynamics. It is much easier to produce a definition of adaptive agent than it is to produce a general formal definition of CAS. Some experiments comparing the evolution of adaptive agents with tags to those without have been carried out. Even a cursory look uncovers many examples of natural agents wherein tags encourage diversity and complexity.
