Political polarization (see American and British English spelling differences) is the extent to which opinions on an issue are opposed, and the process by which this opposition increases over time.
Most discussions of polarization in political science consider polarization in the context of political parties and democratic systems of government. In two-party systems, political polarization usually embodies the tension of its binary political ideologies and partisan identities. However, some political scientists assert that contemporary polarization depends less on policy differences on a left and right scale, but increasingly on other divisions such as: religious against secular; nationalist against globalist; traditional against modern; or rural against urban. Polarization is associated with the process of politicization.
Definitions and measurements
Political scientists typically distinguish between two levels of political polarization: elite and mass. "Elite polarization" focuses on the polarization of the political elites, like party organizers and elected officials. "Mass polarization" (or popular polarization) focuses on the polarization of the masses, most often the electorate or general public.
Elite polarization refers to polarization between the party-in-government and the party-in-opposition. Polarized political parties are internally cohesive, unified, programmatic, and ideologically distinct; they are typically found in a parliamentary system of democratic governance.
In a two-party system, a polarized legislature has two important characteristics: first, there is little-to-no ideological overlap between members of the two parties; and second, almost all conflict over legislation and policies is split across a broad ideological divide. This leads to a conflation of political parties and ideologies (i.e., Democrat and Republican become nearly perfect synonyms for liberal and conservative) and the collapse of an ideological center.
The vast majority of studies on elite polarization focus on legislative and deliberative bodies. For many years, political scientists measured polarization in the US by examining the ratings of party members published by interest groups, but now, most analyze roll-call voting patterns to investigate trends in party-line voting and party unity. Gentzkow, Shapiro, and Taddy used the text of the Congressional Record to document differences in speech patterns between Republicans and Democrats as a measure of polarization, finding a dramatic increase in polarized speech patterns starting in 1994.
Mass polarization, or popular polarization, occurs when an electorate's attitudes towards political issues, policies, celebrated figures, or other citizens are neatly divided along party lines. At the extreme, each camp questions the moral legitimacy of the other, viewing the opposing camp and its policies as an existential threat to their way of life or the nation as a whole.
There are multiple types or measures of mass polarization. Ideological polarization refers to the extent to which the electorate has divergent beliefs on ideological issues (e.g., abortion or affirmative action) or beliefs that are consistently conservative or liberal across a range of issues (e.g., having a conservative position on both abortion and affirmative action even if those positions are not "extreme"). Partisan sorting refers to the extent to which the electorate "sorts" or identifies with a party based on their ideological, racial, religious, gender, or other demographic characteristics. Affective polarization refers to the extent to which the electorate "dislikes" or "distrusts" those from other parties.
Political scientists who study mass polarization typically rely on data from opinion polls and election surveys. They look for trends in respondents' opinions on a given issue, their voting history, and their political ideology (conservative, liberal, moderate, etc.), and they try to relate those trends to respondents' party identification and other potentially polarizing factors (like geographic location or income bracket). Political scientists typically limit their inquiry to issues and questions that have been constant over time, in order to compare the present day to what the political climate has historically been.
Some scholars argue that diverging parties has been one of the major driving forces of polarization as policy platforms have become more distant. This theory is based on recent trends in the United States Congress, where the majority party prioritizes the positions that are most aligned with its party platform and political ideology. The adoption of more ideologically distinct positions by political parties can cause polarization among both elites and the electorate. For example, after the passage of the Voting Rights Act, the number of conservative Democrats in Congress decreased, while the number of conservative Republicans increased. Within the electorate during the 1970s, Southern Democrats shifted toward the Republican Party, showing polarization among both the elites and the electorate of both main parties. In this sense, political polarization could be a top-down process, in which elite polarization leads to—or at least precedes—popular polarization. However, polarization among elites does not necessarily produce polarization within the electorate, and polarized electoral choices can often reflect elite polarization rather than voters' preferences.
Political scientists have shown politicians have an incentive to advance and support polarized positions. These argue that during the early 1990s, the Republican Party used polarizing tactics to become the majority party in the United States House of Representatives—which political scientists Thomas E. Mann and Norman Ornstein refer to as Newt Gingrich's "guerrilla war." What political scientists have found is that moderates are less likely to run than are candidates who are in line with party doctrine, otherwise known as "party fit." Other theories state politicians who cater to more extreme groups within their party tend to be more successful, helping them stay in office while simultaneously pulling their constituency toward a polar extreme. A study by Nicholson (2012) found voters are more polarized by contentious statements from leaders of the opposing party than from the leaders of their own party. As a result, political leaders may be more likely to take polarized stances.
With regards to multiparty systems, Giovanni Sartori (1966, 1976) claims the splitting of ideologies in the public constituency causes further divides within the political parties of the countries. He theorizes that the extremism of public ideological movement is the basis for the creation of highly polarized multiparty systems. Sartori named this polarizing phenomenon polarized pluralism and claimed it would lead to further polarization in many opposing directions (as opposed to in simply two directions, as in a polarized two-party system) over policy issues. Polarization in multiparty systems can also be defined along two ideological extremes, like in the case of India in the 1970s. Ideological splits within a number of India's major parties resulted in two polarized coalitions on the right and left, each consisting of multiple political parties.
Political fund-raisers and donors can also exert significant influence and control over legislators. Party leaders are expected to be productive fund-raisers, in order to support the party's campaigns. After Citizens United v. Federal Election Commission, special interests in the U.S. were able to greatly impact elections through increased undisclosed spending, notably through Super political action committees. Some, such as Washington Post opinion writer Robert Kaiser, argued this allowed wealthy people, corporations, unions, and other groups to push the parties' policy platforms toward ideological extremes, resulting in a state of greater polarization. Other scholars, such as Raymond J. La Raja and David L. Wiltse, note that this does not necessarily hold true for mass donors to political campaigns. These scholars argue a single donor who is polarized and contributes large sums to a campaign does not seem to usually drive a politician toward political extremes.
In democracies and other representative governments, citizens vote for the political actors who will represent them. Some scholars argue that political polarization reflects the public's ideology and voting preferences. Dixit and Weibull (2007) claim that political polarization is a natural and regular phenomenon. They argue that there is a link between public differences in ideology and the polarization of representatives, but that an increase in preference differences is usually temporary and ultimately results in compromise. Fernbach, Rogers, Fox and Sloman (2013) argue that it is a result of people having an exaggerated faith in their understanding of complex issues. Asking people to explain their policy preferences in detail typically resulted in more moderate views. Simply asking them to list the reasons for their preferences did not result in any such moderation.
Morris P. Fiorina (2006, 2008) posits the hypothesis that polarization is a phenomenon which does not hold for the public, and instead is formulated by commentators to draw further division in government. Other studies indicate that cultural differences focusing on ideological movements and geographical polarization within the United States constituency is correlated with rises in overall political polarization between 1972 and 2004.
Religious, ethnic, and other cultural divides within the public have often influenced the emergence of polarization. According to Layman et al. (2005), the ideological split between U.S. Republicans and Democrats also crosses into the religious cultural divide. They claim that Democrats have generally become more moderate in religious views whereas Republicans have become more traditionalist. For example, political scientists have shown that in the United States, voters who identify as Republican are more likely to vote for a strongly evangelical candidate than Democratic voters. This correlates with the rise in polarization in the United States. Another theory contends that religion does not contribute to full-group polarization, but rather, coalition and party activist polarization causes party shifts toward a political extreme.
In some post-colonial countries, the public may be polarized along ethnic divides that remain from the colonial regime. In South Africa in the late 1980s, members of the conservative, pro-apartheid National Party of South Africa were no longer supportive of apartheid, and, therefore, no longer ideologically aligned with their party. Dutch Afrikaners, white English, and native Africans split based on racial divisions, causing polarization along ethnic lines.
Economic inequality can also motivate the polarization of the public. For example, in post-World War I Germany, the Communist Workers Party, and the National Socialists, a fascist party, emerged as the dominant political ideologies and proposed to address Germany's economic problems in drastically different ways. In Venezuela in the late 20th century, the entrance of the oil industry into the local economy caused economic disparities that led to sharp ideological divides. As a result, the disenfranchised working class aligned with extreme socialist leader Hugo Chávez.
The impact of redistricting—potentially through gerrymandering or the manipulation of electoral borders to favor a political party—on political polarization in the United States has been found to be minimal in research by leading political scientists. The logic for this minimal effect is twofold: first, gerrymandering is typically accomplished by packing opposition voters into a minority of congressional districts in a region, while distributing the preferred party's voters over a majority of districts by a slimmer majority than otherwise would have existed. The result of this is that the number of competitive congressional districts would be expected to increase, and in competitive districts representatives have to compete with the other party for the median voter, who tends to be more ideologically moderate. Second, political polarization has also occurred in the Senate, which does not experience redistricting because Senators represent fixed geographical units, i.e. states. The argument that redistricting, through gerrymandering, would contribute to political polarization is based on the idea that new non-competitive districts created would lead to the election of extremist candidates representing the supermajority party, with no accountability to the voice of the minority. One difficulty in testing this hypothesis is to disentangle gerrymandering effects from natural geographical sorting through individuals moving to congressional districts with a similar ideological makeup to their own. Carson et al. (2007), has found that redistricting has contributed to the greater level of polarization in the House of Representatives than in the Senate, however that this effect has been "relatively modest". Politically motivated redistricting has been associated with the rise in partisanship in the U.S. House of Representatives between 1992 and 1994.
The mass media has grown as an institution over the past half-century. Political scientists argue that this has particularly affected the voting public in the last three decades, as previously less partisan viewers are given more polarized news media choices. The mass media's current, fragmented, high-choice environment has induced a movement of the audience from more even-toned political programming to more antagonistic and one-sided broadcasts and articles. These programs tend to appeal to partisan viewers who watch the polarized programming as a self-confirming source for their ideologies.
Countries with less diversified but emerging media markets, such as China and South Korea, have become more polarized due to the diversification of political media. In addition, most search engines and social networks (e.g., Google, Facebook) now utilize computer algorithms as filters, which personalize web content based on a user's search history, location, and previous clicking patterns, creating more polarized access to information. This method of personalizing web content results in filter bubbles, a term coined by digital activist Eli Pariser that refers to the polarized ideological bubbles that are created by computer algorithms filtering out unrelated information and opposing views.
A 2011 study found ideological segregation of online news consumption is lower than the segregation of most offline news consumption and lower than the segregation of face-to-face interactions. This suggests that the filter bubbles effects of online media consumption are exaggerated. Other research also shows that online media does not contribute to the increased polarization of opinions. Solomon Messing and Sean J. Westwood state that individuals do not necessarily become polarized through media because they choose their own exposure, which tends to already align with their views.
Academic studies found that providing people with impartial, objective information has the potential to reduce political polarization, but the effect of information on polarization is highly sensitive to contextual factors. Specifically, polarization over government spending was reduced when people were provided with a "Taxpayer Receipt," but not when they were also asked how they wanted the money to be spent. This suggests that subtle factors like the mood and tone of partisan news sources may have a large effect on how the same information is interpreted. This is confirmed by another study that shows that different emotions of messages can lead to polarization or convergence: joy is prevalent in emotional polarization, while sadness and fear play significant roles in emotional convergence. These findings can help to design more socially responsible algorithms by starting to focus on the emotional content of algorithmic recommendations.
The implications of political polarization "are not entirely clear and may include some benefits as well as detrimental consequences." Polarization can be benign, natural, and democratizing, or it can be pernicious, having long term malignant effects on society and congesting essential democratic functions. Where voters see the parties as less divergent, they are less likely to be satisfied with how their democracy works. While its exact effects are disputed, it clearly alters the political process and the political composition of the general public.
In political science, pernicious polarization occurs when a single political cleavage overrides other divides and commonalities to the point it has boiled into a single divide which becomes entrenched and self-reinforcing. Unlike most types of polarization, pernicious polarization does not need to be ideological. Rather, pernicious polarization operates on a single political cleavage, which can be partisan identity, religious vs secular, globalist vs nationalist, urban vs rural, etc. This political divide creates an explosion of mutual group distrust which hardens between the two political parties (or coalitions) and spreads beyond the political sphere into societal relations. People begin to perceive politics as "us" vs "them."
According to Carothers & O'Donohue (2019), pernicious polarization is a process most often driven by a single political cleavage dominating an otherwise pluralistic political life, overriding other cleavages. On the other hand, Slater & Arugay (2019) have argued that it's not the depth of a single social cleavage, but the political elite's process for removing a leader which best explains whether or not polarization truly becomes pernicious. Lebas & Munemo (2019) have argued pernicious polarization is marked by both deeper societal penetration and segregation than other forms of political polarization, making it less amenable to resolution. It is agreed, however, that pernicious polarization reinforces and entrenches itself, dragging the country into a downward spiral of anger and division for which there are no easy remedies.
Effect on governance
Pernicious polarization makes compromise, consensus, interaction, and tolerance increasingly costly and tenuous for individuals and political actors on both sides of the divide. Pernicious polarization routinely weakens respect for democratic norms, corrodes basic legislative processes, undermines the nonpartisan nature of the judiciary and fuels public disaffection with political parties. It exacerbates intolerance and discrimination, diminishes societal trust, and increases violence throughout the society. In country-by-country instances of pernicious polarization, it is common to see the winner exclude the loser from positions of power or using means to prevent the loser from becoming a threat in the future. In these situations, the loser typically questions the legitimacy of the institutions allowing the winner to create a hegemony, which causes citizens to grow cynical towards politics. In these countries, politics is often seen as a self-referential power game that has nothing to do with people.
Effect on public trust
Perniciously polarized societies often witness public controversies over factually provable questions. During this process, facts and moral truths increasingly lose their weight, as more people conform to the messages of their own bloc. Social and political actors such as journalists, academics, and politicians either become engaged in partisan storytelling or else incur growing social, political, and economic costs. Electorates lose confidence in public institutions. Support for norms and democracy decline. It becomes increasingly difficult for people to act in a morally principled fashion by appealing to the truth or acting in line with one's values when it conflicts with one's party interests. Once pernicious polarization takes hold, it takes on a life of its own, regardless of earlier intentions.
Several political scientists have argued that most types of political polarization are beneficial to democracy, as well as a natural feature. The simplifying features of polarization can help democratization. Strategies which depend on opposition and exclusion are present in all forms of observed politics. Political polarization can help transform or disrupt the status quo, sometimes addressing injustices or imbalances in a popular vs. oligarchic struggle.
Political polarization can serve to unify, invigorate, or mobilize potential allies at the elite and mass levels. It can also help to divide, weaken, or pacify competitors. Even the most celebrated social movements can be described as a "group of people involved in a conflict with clearly defined opponents having a conflictual orientation toward an opponent and a common identity."
Political polarization can also provide voting heuristics to help voters choose among candidates, enabling political parties to mobilize supporters and provide programmatic choices. Polarizing politics can also help to overcome internal differences and frame a common identity, based in part on a common opposition to those resisting reforms. Still, polarization can be a risky political tool even when intended as an instrument of democratization, as it risks turning pernicious and self-propagating.
This section's factual accuracy is disputed. (November 2020)
Outside of the U.S., there are plenty of modern-day examples of polarization in politics. A bulk of the research into global polarization comes from Europe. One example includes Pasokification in Greece. This is the trend from a shift from the center-left to a more far-left stance. Pasokification was caused by the Greek populous growing dissatisfied with the country's centrist, left wing party and how they handled the Great Recession and the austerity measures the European Union put in place during recovery. Although the shift further to the left was a massive benefits to the liberal population in Greece, the results in Greece (as well as other nations like Germany, Sweden and Italy) have not been able to sustain themselves. Parties who have made the shift left have recently shown a decline in the voting booths, evidence their supporters are uneasy of the future.
The shift in Greece to the far-left is similar to the shift in countries like Poland, France and the U.K. to more far-right conservative positions. In those countries, there is heavy anti-Islam sentiment and the rise of populist commentary. The general population of the right in these countries tends to hold onto these more aggressive stances and pulls the parties further to the right. These stances include populist messages with Islamophobic, isolationist, and anti-LGBTQ language. Much of the polarization in these nations leads to either a more socialist left wing party, or more nationalist right wing party. These more polarized parties grow from the discontent of more moderate parties inability to provide progressive changes in either direction.
- Civil war
- Cultural pluralism, in contrast
- Democratic backsliding
- False dilemma
- Income inequality in the United States § Political polarization
- Left–right politics
- Multi-party system
- Partisan (political)
- Political midlife crisis
- State collapse
- DiMaggio, Paul; Evans, John; Bryson, Bethany (1 November 1996). "Have American's Social Attitudes Become More Polarized?" (PDF). American Journal of Sociology. 102 (3): 690–755. doi:10.1086/230995. S2CID 144020785.
- Baldassarri, Delia; Gelman, Andrew (1 September 2008). "Partisans without Constraint: Political Polarization and Trends in American Public Opinion". American Journal of Sociology. 114 (2): 408–446. CiteSeerX 10.1.1.69.255. doi:10.1086/590649. S2CID 222436264.
- Fiorina, Morris P.; Abrams, Samuel J. (1 June 2008). "Political Polarization in the American Public". Annual Review of Political Science. 11 (1): 563–588. doi:10.1146/annurev.polisci.11.053106.153836.
- Abramowitz, Alan I.; Saunders, Kyle L. (27 March 2008). "Is Polarization a Myth?". The Journal of Politics. 70 (2): 542. doi:10.1017/S0022381608080493. S2CID 44020272.
- Bafumi, Joseph; Shapiro, Robert Y. (27 January 2009). "A New Partisan Voter" (PDF). The Journal of Politics. 71 (1): 1. doi:10.1017/S0022381608090014. S2CID 154400302.
- McCoy, Jennifer; Rahman, Tahmina; Somer, Murat (January 2018). "Polarization and the Global Crisis of Democracy: Common Patterns, Dynamics, and Pernicious Consequences for Democratic Polities". American Behavioral Scientist. 62 (1): 16–42. doi:10.1177/0002764218759576. ISSN 0002-7642.
- Chinn, Sedona; Hart, P. Sol; Soroka, Stuart (February 2020). "Politicization and Polarization in Climate Change News Content, 1985-2017". Science Communication. 42 (1): 119–125. doi:10.1177/1075547019900290. S2CID 212781410.
- McCarty, Nolan; Poole, Keith T.; Rosenthal, Howard (2006). Polarized America : the dance of ideology and unequal riches. MIT Press. Cambridge, Mass. ISBN 978-0262134644.
- Hetherington, Marc J. (17 February 2009). "Review Article: Putting Polarization in Perspective". British Journal of Political Science. 39 (2): 413. doi:10.1017/S0007123408000501.
- Layman, Geoffrey C.; Carsey, Thomas M.; Horowitz, Juliana Menasce (1 June 2006). "Party Polarization in American Politics: Characteristics, Causes, and Consequences". Annual Review of Political Science. 9 (1): 83–110. doi:10.1146/annurev.polisci.9.070204.105138.
- Carmines, E. G.; Ensley, M.J.; Wagner, M.W. (23 October 2012). "Who Fits the Left–Right Divide? Partisan Polarization in the American Electorate". American Behavioral Scientist. 56 (12): 1631–1653. doi:10.1177/0002764212463353. S2CID 147108446.
- Mann, Thomas E.; Ornstein, Norman J. (2012). It's Even Worse Than It Looks: How the American constitutional system collided with the new politics of extremism. Basic Books. ISBN 978-0465031337. Archived from the original on 2014-07-05.
- Gentzkow, Matthew, and Shapiro, Jesse, and Taddy, Matt Measuring Polarization in High-Dimensional Data: Method and Application to Congressional Speech"
- Claassen, R.L.; Highton, B. (9 September 2008). "Policy Polarization among Party Elites and the Significance of Political Awareness in the Mass Public". Political Research Quarterly. 62 (3): 538–551. doi:10.1177/1065912908322415. S2CID 154392221.
- "Partisanship and Political Animosity in 2016". Pew Research Center for the People and the Press. 2016-06-22. Retrieved 2019-10-26.
- García-Guadilla, María Pilar; Mallen, Ana (2019-01-01). "Polarization, Participatory Democracy, and Democratic Erosion in Venezuela's Twenty-First Century Socialism". The Annals of the American Academy of Political and Social Science. 681 (1): 62–77. doi:10.1177/0002716218817733. ISSN 0002-7162. S2CID 149617060.
- Abramowitz, Alan I.; Saunders, Kyle L. (2008). "Is Polarization a Myth?". The Journal of Politics. 70 (2): 542–555. doi:10.1017/s0022381608080493. ISSN 0022-3816. JSTOR 10.1017/s0022381608080493. S2CID 44020272.
- Mason, Lilliana (2015). ""I Disrespectfully Agree": The Differential Effects of Partisan Sorting on Social and Issue Polarization". American Journal of Political Science. 59 (1): 128–145. doi:10.1111/ajps.12089. ISSN 0092-5853. JSTOR 24363600.
- Mason, Lilliana; Wronski, Julie (2018). "One Tribe to Bind Them All: How Our Social Group Attachments Strengthen Partisanship". Political Psychology. 39 (S1): 257–277. doi:10.1111/pops.12485. ISSN 1467-9221.
- Iyengar, Shanto; Lelkes, Yphtach; Levendusky, Matthew; Malhotra, Neil; Westwood, Sean J. (2019-05-11). "The Origins and Consequences of Affective Polarization in the United States". Annual Review of Political Science. 22 (1): 129–146. doi:10.1146/annurev-polisci-051117-073034. ISSN 1094-2939.
- Ura, Joseph Daniel; Ellis, Christopher R. (10 February 2012). "Partisan Moods: Polarization and the Dynamics of Mass Party Preferences". The Journal of Politics. 74 (1): 277–291. doi:10.1017/S0022381611001587. hdl:1969.1/178724. S2CID 55325200.
- Abramowitz, Alan I.; Saunders, Kyle L. (August 1998). "Ideological Realignment in the U.S. Electorate". The Journal of Politics. 60 (3): 634. doi:10.2307/2647642. JSTOR 2647642. S2CID 154980825.
- Galston, William A. (2009). "Political Polarization and the U.S. Judiciary". UKMC Law Review. 77 (207).
- Benkler, Yochai (2018). Network Propaganda: Manipulation, Disinformation, and Radicalization in American Politics. Oxford Scholarship Online (published 2018-10-01). doi:10.1093/oso/9780190923624.003.0010. ISBN 978-0-19-092366-2.
- Beniers, Klaas J.; Dur, Robert (1 February 2007). "Politicians' motivation, political culture, and electoral competition" (PDF). International Tax and Public Finance. 14 (1): 29–54. doi:10.1007/s10797-006-8878-y. S2CID 39796862.
- Thomsen, Danielle M. (2014). "Ideological Moderates Won't Run: How Party Fit Matters for Partisan Polarization in Congress". The Journal of Politics. 76 (3): 786–797. doi:10.1017/s0022381614000243. hdl:10161/8931. JSTOR 0022381614000243. S2CID 154980416.
- Hirano, Shigeo, Jr.; James M. Snyder; Michael M. Ting (2009). "Distributive Politics with Primaries" (PDF). Journal of Politics. 71 (4): 1467–1480. doi:10.1017/s0022381609990247. S2CID 11453544.
- Nicholson, Stephen P. (1 January 2012). "Polarizing Cues". American Journal of Political Science. 56 (1): 52–66. doi:10.1111/j.1540-5907.2011.00541.x. PMID 22400143.
- Sartori, Giovanni (1966). "European political parties: the case of polarized pluralism". Political Parties and Political Development: 137–176. doi:10.1515/9781400875337-006. ISBN 978-1400875337.
- Sartori, Giovanni (1976). Parties and party systems : a framework for analysis ([Nouvelle édition] ed.). Colchester: ECPR. ISBN 978-0954796617.
- Johnston, Richard (17 December 2008). "Polarized Pluralism in the Canadian Party System: Presidential Address to the Canadian Political Science Association, June 5, 2008". Canadian Journal of Political Science. 41 (4): 815. doi:10.1017/S0008423908081110. S2CID 154599342.
- Davey, Hampton (1 August 1972). "Polarization and Consensus in Indian Party Politics". Asian Survey. 12 (8): 701–716. doi:10.2307/2643110. JSTOR 2643110.
- Kaiser, Robert G. (2010). So damn much money : the triumph of lobbying and the corrosion of American government (1st Vintage Books ed.). New York: Vintage Books. ISBN 978-0307385888.
- La Raja, R.J.; Wiltse, D.L. (13 December 2011). "Don't Blame Donors for Ideological Polarization of Political Parties: Ideological Change and Stability Among Political Contributors, 1972–2008". American Politics Research. 40 (3): 501–530. doi:10.1177/1532673X11429845. S2CID 143588919.
- Tam Cho, Wendy K.; Gimpel, James G. (1 April 2007). "Prospecting for (Campaign) Gold" (PDF). American Journal of Political Science. 51 (2): 255–268. doi:10.1111/j.1540-5907.2007.00249.x.
- Garner, Andrew; Palmer, Harvey (June 2011). "Polarization and issue consistency over time". Political Behavior. Springer. 33 (2): 225–246. doi:10.1007/s11109-010-9136-7. S2CID 143137236.
- Mason, Lilliana (January 2013). "The rise of uncivil agreement: issue versus behavioral polarization in the American electorate". American Behavioral Scientist. Sage. 57 (1): 140–159. doi:10.1177/0002764212463363. S2CID 147084342.
- Murakami, Michael H. (2007). "How party polarization affects candidate evaluations: the role of ideology". Paper Presented at the Annual Meeting of the American Political Science Association, Hyatt Regency Chicago and the Sheraton Chicago Hotel and Towers, Chicago, Illinois.
- Dixit, Avinash K.; Weibull, Jörgen W. (1 May 2007). "Political polarization". Proceedings of the National Academy of Sciences. National Academy of Sciences. 104 (18): 7351–7356. Bibcode:2007PNAS..104.7351D. doi:10.1073/pnas.0702071104. JSTOR 25427490. PMC 1863477. PMID 17452633.
- Fernbach, Phillip; Rogers, Todd; Fox, Craig; Sloman, Steven (25 April 2013), "Political Extremism Is Supported by an Illusion of Understanding" (PDF), Psychological Science, 24 (6): 939–946, doi:10.1177/0956797612464058, PMID 23620547, S2CID 6173291
- Fiorina, Morris P.; Samuel A. Abrams; Jeremy C. Pope (2006). Culture War? The Myth of a Polarized America. Pearson Longman. ISBN 978-0321276407.
- Born, Richard (February 1994). "[Split-ticket voters, divided government, and Fiorina's policy-balancing model]: rejoinder". Legislative Studies Quarterly. American Political Science Association. 19 (1): 126–129. doi:10.2307/439804. JSTOR 439804.
- Abramowitz, Alan; Saunders, Kyle L. (July 2005). "Why can't we all just get along? The reality of polarized America" (PDF). The Forum. De Gruyter. 3 (2): 1–22. doi:10.2202/1540-8884.1076. S2CID 145471342. Archived from the original on 2013-10-19.CS1 maint: bot: original URL status unknown (link)
- Campbell, David E.; Green, John C.; Layman, Geoffrey C. (January 2011). "The party faithful: partisan images, candidate religion, and the electoral impact of party identification". American Journal of Political Science. Wiley. 55 (1): 42–58. doi:10.1111/j.1540-5907.2010.00474.x.
- Layman, Geoffrey C.; Green, John C. (January 2006). "Wars and rumours of wars: the contexts of cultural conflict in American political behaviour". British Journal of Political Science. Cambridge Journals. 36 (1): 61–89. doi:10.1017/S0007123406000044. JSTOR 4092316. S2CID 144870729.
- Brooks, Clem; Manza, Jeff (1 May 2004). "A great divide? Religion and political change in U.S. national elections, 1972–2000" (PDF). The Sociological Quarterly. Wiley. 45 (3): 421–450. doi:10.1111/j.1533-8525.2004.tb02297.x. S2CID 1887424. Archived from the original (PDF) on 11 June 2010. Retrieved 22 April 2013.
- Bhavnani, Ravi; Miodownik, Dan (February 2009). "Ethnic polarization, ethnic salience, and Civil War". Journal of Conflict Resolution. Sage. 53 (1): 30–49. doi:10.1177/0022002708325945. S2CID 145686111.
- Sisk, Timothy D. (January 1989). "White politics in South Africa: politics under pressure". Africa Today. Indiana University Press. 36 (1): 29–39. JSTOR 4186531.
- Darity, William A. (2009), "Economic theory and racial economic inequality", in Dodson, Howard; Palmer, Colin A. (eds.), The Black condition, East Lansing, Michigan: Michigan State University Press, pp. 1–43, ISBN 978-0870138386.
- Lombardi, John V. (2004), "Prologue: Venezuela's Permanent Dilemma", in Ellner, Steve; Hellinger, Daniel (eds.), Venezuelan politics in the Chávez era: class, polarization, and conflict, Boulder, Colorado: Rienner, ISBN 978-1588262974
- McCarty, Nolan; Poole, Keith T.; Rosenthal, Howard (1 July 2009). "Does Gerrymandering Cause Polarization?". American Journal of Political Science. 53 (3): 666–680. doi:10.1111/j.1540-5907.2009.00393.x.
- Masket, Seth E.; Winburn, Jonathan; Wright, Gerald C. (4 January 2012). "The Gerrymanderers Are Coming! Legislative Redistricting Won't Affect Competition or Polarization Much, No Matter Who Does It" (PDF). PS: Political Science & Politics. 45 (1): 39–43. doi:10.1017/S1049096511001703. S2CID 45832354.
- Carson, J.L.; Crespin, M.H.; Finocchiaro, C.J.; Rohde, D.W. (28 September 2007). "Redistricting and Party Polarization in the U.S. House of Representatives". American Politics Research. 35 (6): 878–904. doi:10.1177/1532673X07304263. S2CID 154527252.
- McKee, SEth C. (March 2008). "The Effects of Redistricting on Voting Behavior in Incumbent U.S. House Elections, 1992–1994". Political Research Quarterly. 61 (1): 122–133. doi:10.1177/1065912907306473. S2CID 154836818. ProQuest 215329960.
- Kousser, J (November 1996). "Estimating the Partisan Consequences of Redistricting Plans – Simply" (PDF). Legislative Studies Quarterly. 21 (4): 521–541. doi:10.2307/440460. JSTOR 440460. ProQuest 60821189.
- Hollander, B.A. (1 March 2008). "Tuning Out or Tuning Elsewhere? Partisanship, Polarization, and Media Migration from 1998 to 2006". Journalism & Mass Communication Quarterly. 85 (1): 23–40. doi:10.1177/107769900808500103. S2CID 144996244.
- Yuan, Elaine Jingyan (2007). The New Multi-channel Media Environment in China: Diversity of Exposure in Television Viewing. Northwestern University. ISBN 978-1109940213.
- Kim, S.J. (2011). Emerging patterns of news media use across multiple platforms and their political implications in south korea. Northwestern University. ProQuest 873972899.
- Rushkoff, D. (2010). Program or be programmed: Ten commands for a digital age. Berkeley, CA: Soft Skull Press.
- Pariser, E. (2011). The filter bubble: What the internet is hiding from you. New York, NY: The Penguin Press.
- Gentzkow, Matthew; Shapiro, Jesse M. (2011-11-01). "Ideological Segregation Online and Offline *" (PDF). The Quarterly Journal of Economics. 126 (4): 1799–1839. doi:10.1093/qje/qjr044. hdl:1811/52901. ISSN 0033-5533. S2CID 9303073.
- Hohenberg, Clemm von; Bernhard; Maes, Michael; Pradelski, Bary S.R. (2017-05-25). "Micro influence and macro dynamics of opinions". SSRN 2974413. Cite journal requires
- Messing, Solomon; Westwood, Sean (31 Dec 2012). "Selective Exposure in the Age of Social Media". Communication Research. 41 (8): 1042–1063. doi:10.1177/0093650212466406. S2CID 35373607.
- Duhaime, Erik; Apfelbaum, Evan (2017). "Can Information Decrease Political Polarization? Evidence From the U.S. Taxpayer Receipt". Social Psychological and Personality Science. 8 (7): 736. doi:10.1177/1948550616687126. S2CID 151758489.
- Hilbert, M., Ahmed, S., Cho, J., Liu, B., & Luu, J. (2018). Communicating with Algorithms: A Transfer Entropy Analysis of Emotions-based Escapes from Online Echo Chambers. Communication Methods and Measures, 12(4), 260–275. https://doi.org/10.1080/19312458.2018.1479843 ; https://www.martinhilbert.net/communicating-with-algorithms/
- Epstein, Diana; John D. Graham (2007). "Polarized Politics and Policy Consequences" (PDF). Rand Corporation.
- "Varieties of Democracy Report 2019" (PDF).
- Ridge, Hannah M (2021-01-20). "Just like the others: Party differences, perception, and satisfaction with democracy". Party Politics: 135406882098519. doi:10.1177/1354068820985193. ISSN 1354-0688. S2CID 234162430.
- Pietro S. Nivola & David W. Brady, ed. (2006). Red and blue nation? Volume One: characteristics and causes of America's polarized politics. Washington, DC: Brookings Institution. ISBN 978-0815760832.
- Pietro S. Nivola & David W. Brady, ed. (2008). Red and blue nation? Volume Two: Consequences and Correction of America's Polarized Politics ([Online-Ausg.] ed.). Washington, DC: Brookings Institution. ISBN 978-0815760801.
- McCoy, Jennifer; Rahman, Tahmina (2016-07-25). "Polarized Democracies in Comparative Perspective: Toward a Conceptual Framework". Cite journal requires
- McCoy, Jennifer; Somer, Murat (2019-01-01). "Toward a Theory of Pernicious Polarization and How It Harms Democracies: Comparative Evidence and Possible Remedies". The Annals of the American Academy of Political and Social Science. 681 (1): 234–271. doi:10.1177/0002716218818782. ISSN 0002-7162. S2CID 150169330.
- Somer, Murat; McCoy, Jennifer (2019-01-01). "Transformations through Polarizations and Global Threats to Democracy". The Annals of the American Academy of Political and Social Science. 681 (1): 8–22. doi:10.1177/0002716218818058. ISSN 0002-7162. S2CID 149764414.
- and (2019-04-01). "Democracies Divided". Brookings. Retrieved 2019-11-24.
- Arugay, Slater, Aires, Dan (2019). "Polarizing Figures: Executive Power and Institutional Conflict in Asian Democracies". American Behavioral Scientist. 62: 92–106. doi:10.1177/0002764218759577.
- LeBas, Adrienne; Munemo, Ngonidzashe (2019-01-01). "Elite Conflict, Compromise, and Enduring Authoritarianism: Polarization in Zimbabwe, 1980–2008". The Annals of the American Academy of Political and Social Science. 681 (1): 209–226. doi:10.1177/0002716218813897. ISSN 0002-7162. S2CID 150337601.
- Somer, McCoy, Murat, Jennifer (2018). "Deja Vu? Polarization and Endangered Democracies in the 21st Century". American Behavioral Scientist. 62: 3–15. doi:10.1177/0002764218760371.
- Vegetti, Federico (2019-01-01). "The Political Nature of Ideological Polarization: The Case of Hungary". The Annals of the American Academy of Political and Social Science. 681 (1): 78–96. doi:10.1177/0002716218813895. ISSN 0002-7162. S2CID 199896426.
- Schattschneider, E. E. (Elmer Eric) (1975). The semisovereign people: a realist's view of democracy in America. Boston, MA: Wadsworth Cengage Learning. ISBN 978-0030133664.
- Stavrakakis, Yannis (January 2018). "Paradoxes of Polarization: Democracy's Inherent Division and the (Anti-) Populist Challenge". American Behavioral Scientist. 62 (1): 43–58. doi:10.1177/0002764218756924. ISSN 0002-7642.
- Slater, Dan (2013). Diamond, Larry; Kapstein, Ethan B.; Converse, Nathan; Mattlin, Mikael; Phongpaichit, Pasuk; Baker, Chris (eds.). "Democratic Careening". World Politics. 65 (4): 729–763. doi:10.1017/S0043887113000233. ISSN 0043-8871. JSTOR 42002228. S2CID 201767801.
- Kriesi, Hanspeter (2017). "16. Social movements". In Caramani, Daniele (ed.). Comparative Politics (4th ed.). Oxford University Press. doi:10.1093/hepl/9780198737421.003.0018. ISBN 978-0191851018.
- Campbell, James E. (2016). Polarized. ISBN 978-0691172163.
- Blackwater, Bill (Summer 2016). "Morality and left-wing politics: a case study of Jeremy Corbyn's Labour Party". Renewal. 24 – via Gale Literature Resource Center.
- Eaton, George (2018). "Corbynism 2.0". New Statesman. 147.
- Zarkov, Dubravka (2017-06-16). "Populism, polarization and social justice activism". European Journal of Women's Studies. 24 (3): 197–201. doi:10.1177/1350506817713439. ISSN 1350-5068.
- Palonen, Emilia (2009). "Political Polarisation and Populism in Contemporary Hungary". Parliamentary Affairs. 62 (2): 318–334. doi:10.1093/pa/gsn048 – via Electronic Journal Center.
- Abramowitz, Alan (1994). "Issue Evolution Reconsidered: Racial Attitudes and Partisanship in the U.S. Electorate". The Sociological Quarterly. 38 (1): 1–24. JSTOR 2111333.
- Clark, Cal; Tan, Alexander C. (2012). "Political Polarization in Taiwan: A Growing Challenge to Catch-all Parties?" (PDF). Journal of Current Chinese Affairs. 41 (3): 7–31. doi:10.1177/186810261204100302. S2CID 73640516.
- Frymer, Paul. "Debating the Causes of Party Polarization in America". The Brennan Center Jorde Symposium on Constitutional Law. 2011: 335–350.
- Kallis, Aristotle A. Fascist ideology: territory and expansionism in Italy and Germany, 1922–1945. London, England; New York: Routledge, 2000.
- Keefer, Philip; Knack, Stephen (2002). "Polarization, Politics and Property Rights: Links between Inequality and Growth". Public Choice. 111 (1/2): 127–154. doi:10.1023/A:1015168000336. JSTOR 30026274. S2CID 9467286.
- Leege, David C., Kenneth D. Wald, Brian S. Krueger, and Paul D. Mueller. The Politics of Cultural Differences: Social Change and Voter Mobilization Strategies in the Post-New Deal Period. N.p.: University of Florida, 2001.
- McCarty, Nolan M. "Limits of Electoral and Legislative Reform in Addressing Polarization". The Brennan Center Jorde Symposium on Constitutional Law. 359: 359–372.
- Nivola, Peter. "Thinking About Political Polarization." The Brookings Institution, Jan. 2005.
- Pierson, Paul and Eric Schickler. 2020. "Madison's Constitution Under Stress: A Developmental Analysis of Political Polarization." Annual Review of Political Science 23:1, 37-58
- Simon, Sheldon W. (1979). "China, Vietnam, and ASEAN: The Politics of Polarization". Asian Survey. 19 (12): 1171–1188. doi:10.2307/2643963. JSTOR 2643963.
- Pew Research Center, Political Polarization in the American Public, June 12, 2014, people-press.org.
- Stewart, Alexander J.; McCarty, Nolan; Bryson, Joanna J. (2020). "Polarization under rising inequality and economic decline". Science Advances. 6 (50): eabd4201. arXiv:1807.11477. Bibcode:2020SciA....6.4201S. doi:10.1126/sciadv.abd4201. PMC 7732181. PMID 33310855. S2CID 216144890.
- Sunstein, Cass R (2001). "Deliberative Trouble – Why Groups Go to Extremes". Yale Law Journal. 110 (71): 71–120. doi:10.2307/797587. JSTOR 797587.