Discussion papers

CPM-17-235 - 17 February 2017

Co-developing beliefs and social influence networks – towards understanding Brexit

Bruce Edmonds

A discussion paper by Bruce Edmonds

An abstract agent-based model where beliefs and social network co-evolve is applied to understanding the kind of processes that might have been at work during the Brexit vote.


A relatively simple model is presented where the beliefs of agents and their social network co-develop. Agents can either hold or not each of a fixed menu of candidate beliefs. Depending on their type, agents have different coherency functions between beliefs, so that they are more likely to adopt a belief from a neighbour or drop a belief where this increases the total coherency of their belief set. With given probabilities links are randomly dropped or added but, if possible, links are made to a “friend of a friend”. The outcomes when both belief and link change processes occur are qualitatively different from either alone, showing the necessity of representing both cognitive and social processes together. Some example results are shown which moves a little towards modelling the processes behind divisive collective decisions, such as the Brexit vote.


The paper can be downloaded at: http://cfpm.org/file_download/177/BE-co-evolving+belliefs+and+social+network-AISB08.pdf

The model can be accessed at: http://www.openabm.org/model/5116

Some slides that discuss the model are at: https://www.slideshare.net/BruceEdmonds/a-model-of-social-and-cognitive-coherence