Individual Experience and the Fragmentation of Societies

Abstract

We use computer simulations to show how social fragmentation and consequent social loss can result from six innocuous cognitive and behavioral assumptions. These assumptions govern individuals' choices with respect to each other and are independent of processes associated with fragmentation in various classical literatures. We model society as a set of individuals who encounter each other in circumstances that permit potentially productive but also risky relationships with each other Individuals (1) have the option of playing Prisoner's Dilemma games with others they encounter but they do not have to; (2) have preferences over mutual cooperation and free-riding outcomes; (3) have expectations about each other's play; (4) have observable category tags; (5) can modify their future responses to tagged individuals based on experience; (6) can search out partners they believe represent good prospects for productive relationships. In these terms, the only condition necessary for fragmentation to emerge is that some circumstance makes the probability of encounters across tagged categories unequal, and a difference in sizes of categories, however slight, is sufficient to do that. Some difference in category sizes is, for practical purposes, inevitable, and thus so are pressures toward fragmentation