Sunstein argues that this mechanism is behind the rise in the number of hate
groups and extremist organizations with a strong online presence, such as white
supremacists and Holocaust deniers. Other scholars have used this argument as
an explanation for the emergence of groups with less nefarious intentions but
whose success can be equally polarizing. For example, in their book The Outrage
Industry, Berry and Sobieraj (2013, p. 165) document how digital tools were
critical to the emergence and organization of the Tea Party movement. They
lowered the barriers to entry for those who wanted to get involved and offered
a space where political messages could be reﬁned and agreed on.

The literature on social networks has also addressed this question in the
context of studies of homophily; that is, individuals’ propensity to cluster based
on common traits, such as political ideology (McPherson, Smith-Lovin, and
Cook 2001). Adamic and Glance (2005) analyzed the network of hyperlinks
Social_Media_and_Democracy