Social phase transitions

In many social systems a small event (or parameter change) can trigger a dramatic transition. We show that social systems whose individuals have an inclination to conform to each other may undergo "phase transitions" very similar to statistical mechanic systems. We develop a general criterion that determines whether a given social system is susceptible to undergo a phase transition and show that phase transitions may occur in a wide range of social systems. The heterogeneity of the agents comprising the system is shown to play a crucial role in determining both the possibility of a transition and its magnitude. (c) 2004 Elsevier B.V. All rights reserved.