Populism and Polarization in Social Media Without Fake News: The Vicious Circle of Biases, Beliefs and Network Homophily

Abstract

We build a model of network dynamics with decision-making under incomplete information in order to understand the determinants of the observed gradual downgrading of expert opinion on complicated issues and the decreasing trust in science. We suggest a search and matching mechanism behind network formation of friends, claiming that the internet has made search and matching less costly and more intensive. According to our simulations, just combining the internet's ease of forming networks with (a) individual biases, such as confirmation bias or assimilation bias, and (b) people's tendency to align their actions with those of peers, can lead to populist dynamics over time through a vicious circle. Even without fake news, biases lead to more network homophily and, over time, more homophily leads to actions that put more weight on biases and less weight on expert opinion. Networks make fundamental biases be enhanced by peer-induced amplification factors, a finding suggesting that education should perhaps focus on mitigating fundamental biases by promoting evidence-based attitudes towards complicated social and scientific issues.