The Role of Argument Strength and Informational Biases in Polarization and Bi-Polarization Effects

This work explores, on a simulative basis, the informational causes of polarization and bi-polarization of opinions in groups. Here, the term 'polarization' refers to a uniform change of the opinion of the whole group towards the same direction, whereas 'bi-polarization' indicates a split of two subgroups towards opposite directions. For the purposes of the present inquiry we expand the model of the Argument Communication Theory of Bi-polarization. The latter is an argument-based multi-agent model of opinion dynamics inspired by Persuasive Argument Theory. The original model can account for polarization as an outcome of pure informational influence, and reproduces bi-polarization effects by postulating an additional mechanism of homophilous selection of communication partners. The expanded model adds two dimensions: argument strength and more sophisticated protocols of informational influence (argument communication and opinion update). Adding the first dimension allows to investigate whether and how the presence of stronger or weaker arguments in the discussion influences polarization and bi-polarization dynamics, as suggested by the original framework of Persuasive Arguments Theory. The second feature allows to test whether other mechanisms related to confirmation bias and epistemic vigilance can act as a driving force of bi-polarization. Regarding the first issue, the simulations we perform show that argument strength has a measurable effect. With regard to the second, our results witness that, in absence of homophily, only very strong types of informational bias can lead to bi-polarization.