Matt Schissler with these beliefs.4 For Pariser, this dynamic is produced by the invisible algorithms Google, Facebook and others use to filter content. For Sunstein, it is produced by the choices individuals make about who to listen to and take advice from and what to read. For both, the consequences for a democratic society are severe. At the time Republic.com was first being published, one of the most controversial presidential elections in recent US history was being decided. The 2000 Presidential election was too close to call; the views of how to proceed reflected the polarized views of the US two party system, with the outcome ultimately decided by the Supreme Court. In an essay on these events, Sunstein argued that the election controversy was not the result of simple partisanship, but instead the product of the same media environment described in Republic.com. “The phenomenon, sometimes called group polarization, involves the tendency of like-minded individuals engaged in discussion with one another to fortify their pre-existing views – and indeed to move toward more extreme points of view in the general direction in which they were already tending,” he wrote. “If Republicans are talking only with Republicans, if Democrats are talking primarily with Democrats… there is a potential for the development of different forms of extremism, and for profound mutual misunderstandings with individuals outside the group.”5 Sunstein was writing before the rise of ‘social media’ such as Facebook, which has subsequently become a dominant media platform. Nearly ten years after the site came online in 2004, a survey released by the Pew Research centre in December 2013 found that 73% of adults in the US were using some form of social media, with 63% of adults checking Facebook at least once a day.6 Facebook, meanwhile, is seeking to establish itself not just as a social network but, as founder Mark Zuckerberg announced in March 2013, “the best personalized newspaper in world.”7 Research released by Pew a few months later found that approximately half its users get news from Facebook,8 a number that represents 30% of the US population. That Facebook could enhance this echo chamber should not be surprising. Facebook users interact with and, as the Pew poll shows, receive information from “friends.” And these self-selected “friends” are often highly similar to the user. Sociologists describe this as a tendency towards homophily in social networks, which is another way to say “birds of a feather flock together.”9 As I watched the 2012 US presidential election, in other words, my window opened into an echo chamber populated, predictably, mostly by people like me; we had, after all, just the one satellite news channel, and we were interpreting it with the aid of the updates we were receiving on our newsfeeds. The election I saw was an election described in the comments and articles linked to by Democrats; I did not ‘see’ the election so much as read about it, via content carefully curated by other people with political viewpoints similar to my own. Republicans in rural Pennsylvania saw something different. If Pariser, Sunstein and others are right, the difference between my Facebook newsfeed and that of my friend from Pennsylvania is more than just a reflection of the dominant political viewpoints in our hometowns. The difference between the kinds of 4 Cass R. Sunstein, Republic.com (Princeton University Press, 2002). See also, Cass R. Sunstein, “Neither Hayek nor Habermas,” Public Choice 134, no. 1–2 (January 1, 2008): 87–95, doi:10.1007/s11127-007-9202-9. 5 Cass R. Sunstein, Echo Chambers: Bush V. Gore, Impeachment, and Beyond (Princeton University Press, 2001), 5. 6 Aaron Smith, “Social Media Update 2013,” Pew Research Center’s Internet & American Life Project, December 30, 2013, http://www.pewinternet.org/2013/12/30/social-media-update-2013/. 7 Kevin Morris, “Facebook Is No Longer a Social Network,” The Daily Dot, March 7, 2013, http://www.dailydot.com/business/facebook-no-longer-social-network-news-feed/. 8 Amy Mitchell, “News Use Across Social Media Platforms,” Pew Research Center’s Journalism Project, November 14, 2013, http://www.journalism.org/2013/11/14/news-use-across-social-media-platforms/. 9 Miller McPherson, Lynn Smith-Lovin, and James M Cook, “Birds of a Feather: Homophily in Social Networks,” Annual Review of Sociology 27 (August 2001): 415–44. 3/13