The author of this paper has written extensively about the effect of ideological "echo chambers", enormously facilitated by the internet and social media, where people with similar views but little cross-fertilization with other perspectives tend to talk each other into adopting more extreme positions.
I have observed this phenomenon during my time as a Labor MP when the left would caucus together to discuss some issue, In 1985, for example, there was a meeting to talk about tax reform, when then-treasurer Paul Keating was pushing for a broad-based consumption tax, which the left opposed because of its distributive implications. By the end of this meeting the faction resulted not just to oppose the new tax, but to seek the abolition of all existing indirect taxes, a downright nutty position.
This explains the phenomenon described in a more recent article included in this week's Readings (see above) documenting the acceleration in polarization between 2004 and 2017, the period when social media was widely adopted, which could also explain the stronger polarizing trend on the left than the right, given the younger average age of the former.
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Abstract
In a striking empirical regularity, deliberation tends to move groups, and the individuals whocompose them, toward a more extreme point in the direction indicated by their ownpredeliberation judgments. For example, people who are opposed to the minimum wage arelikely, after talking to each other, to be still more opposed; people who tend to support guncontrol are likely, after discussion, to support gun control with considerable enthusiasm; peoplewho believe that global warming is a serious problem are likely, after discussion, to insist onsevere measures to prevent global warming. This general phenomenon -- group polarization --has many implications for economic, political, and legal institutions. It helps to explainextremism, “radicalization,” cultural shifts, and the behavior of political parties and religiousorganizations; it is closely connected to current concerns about the consequences of the Internet;it also helps account for feuds, ethnic antagonism, and tribalism. Group polarization bears on theconduct of government institutions, including juries, legislatures, courts, and regulatorycommissions. There are interesting relationships between group polarization and social cascades,both informational and reputational. Normative implications are discussed, with special attentionto political and legal institutions.