Radicalizing Populism and the Making of an Echo Chamber: The Case of the Italian Anti-Vaccination Movement

Echo chambers, or environments in which a person's beliefs are constantly affirmed, are widely believed to be breeding grounds for extremism and polarization (Jamieson and Capella 2008; Sunstein 2009a). Yet some scholars have concluded these dangers are overstated when looking at data about media use (Dubois and Blank 2018; Zuiderveen Borgesius et al. 2016). The question of how widespread and dangerous echo chambers really are has recently divided media scholarship. Perhaps, though, their disagreement is due to a difference in the fundamental definition of echo chambers. This is argued by philosopher Thi Nguyen (2020), who shows that empirical studies downplaying the prevalence and danger of echo chambers actually conflate them with the related phenomenon of filter bubbles. Whereas the latter are characterized by a lack of exposure to diverging opinions, the former actively exclude and discredit dissenting voices. On Nguyen's definition, echo chambers are established by creating a trust asymmetry between members and non-members which insulates insider beliefs from rebuttal.