Disagreement and fragmentation in growing groups

TL;DR

This paper presents an analytically tractable model demonstrating that disagreement naturally emerges and leads to fragmentation in growing social groups, regardless of noise level, with outcomes robust across growth mechanisms.

Contribution

The paper introduces a new model of group formation with multidimensional opinions, analytically showing spontaneous disagreement and inevitable fragmentation in large groups.

Findings

Disagreement emerges spontaneously in growing groups.

Fragmentation is inevitable in infinite-sized groups.

Model outcomes are robust under different growth mechanisms.

Abstract

The arise of disagreement is an emergent phenomenon that can be observed within a growing social group and, beyond a certain threshold, can lead to group fragmentation. To better understand how disagreement emerges, we introduce an analytically tractable model of group formation where individuals have multidimensional binary opinions and the group grows through a noisy homophily principle, i.e., like-minded individuals attract each other with exceptions occurring with some small probability. Assuming that the level of disagreement is correlated with the number of different opinions coexisting within the group, we find analytically and numerically that in growing groups disagreement emerges spontaneously regardless of how small the noise in the system is. Moreover, for groups of infinite size, fragmentation is inevitable. We also show that the model outcomes are robust under different group growth mechanisms.