||The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (February 2015)|
In the world of politics, polarization (or polarisation) can refer to the divergence of political attitudes to ideological extremes. Polarization can refer to such divergence like public opinion or even to such divergence within certain groups. Almost all discussions of polarization in political science consider polarization in the context of political parties and democratic systems of government. When polarization occurs in a two-party system, like the United States, moderate voices often lose power and influence. According to the Pew Forum, America has never been more polarized.
- 1 Definitions and measurements
- 2 Causes
- 3 Effects
- 4 Critiques
- 5 See also
- 6 Further reading
- 7 References
Definitions and measurements
Political polarization refers to cases in which an individual's stance on a given issue, policy, or person is more likely to be strictly defined by their identification with a particular political party (e.g., Democrat or Republican) or ideology (e.g., liberal or conservative). According to DiMaggio et al. (1996), "Polarization is both a state and a process. Polarization as a state refers to the extent to which opinions on an issue are opposed in relation to some theoretical maximum. Polarization as a process refers to the increase in such opposition over time." Some political scientists argue that polarization requires divergence on a broad range of issues based on a consistent set of beliefs. Others argue polarization occurs when there are stark partisan or ideological divides, even if opinion is polarized only on a few issues.
Political scientists typically distinguish between two types of political polarization: elite polarization and popular polarization. "Elite polarization" refers to the polarization of political elites, like party organizers and elected officials, while "popular polarization" (or mass polarization) refers to polarization in the electorate and general public. In either context, opinions and policy positions are characterized by strict adherence to party lines. Elite polarization and popular polarization can occur at the same time or independently of each other. A central issue in the study of political polarization is investigating the relationship between elite polarization and popular polarization, particularly any causal relationships between the two.
Elite polarization refers to polarization in the party-in-government and party-as-organization. It occurs when party members (both elected government officials and activists within the party organization itself) grow more internally homogenous on policy positions and more divergent relative to members of other parties. Polarized political parties are internally cohesive and unified, programmatic, and ideologically distinct, and are typically found in a parliamentary system of democratic governance. In a two-party system like the U.S., 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 the broad liberal/conservative ideological divide. This leads to the conflation of political parties and ideologies (e.g., Democrat and Republican become nearly perfect synonyms for liberal and conservative) and the collapse of the ideological center.
The vast majority of studies on elite polarization focus on legislative and deliberative bodies. For many years, political scientists measured polarization by examining the ratings of party members published by interest groups, but now, most analyze roll-call voting patterns to determine trends in party-line voting and party unity. Many political scientists studying American politics rely on Poole and Rosenthal's DW-NOMINATE scores, which assign a single liberal-conservative score to each congressperson, enabling comparisons of members from different Congresses. There is much more research on polarization in Congress than on polarization in the other branches of government or in state governments . Azzimonti's political polarization index is more comprehensive instead, because it based on media coverage of newspaper articles reporting political disagreement about policy in all branches of government. 
Popular polarization occurs when the electorate's attitudes towards political issues, policies, and people are starkly divided along partisan lines. Members of the electorate and general public typically become less moderate in cases of popular polarization. In the U.S., media accounts typically simplify popular polarization to a divide between red states and blue states or a "culture war" between values-voters and progressives, yet political scientists generally agree that such accounts are too simplistic and ignore the complex factors that can account for polarization. Many political scientists consider political polarization a top-down process, in which elite polarization leads to - or at least precedes - popular polarization. Yet polarization amongst elites does not necessarily produce polarization within the electorate, and polarized electoral choices can often reflect elite polarization (resulting in highly polarized policies and candidates) rather than voters' preferences.
Political scientists studying popular 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. Oft-cited public opinion polls in the U.S. include those run by the Pew Research Center and Gallup, Inc., while political scientists also rely on more academic surveys, like the General Social Survey and the election surveys and "feeling thermometer" polls conducted by National Election Studies.
Some scholars argue that diverging parties have 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 amongst 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 amongst both the elites and the electorate of both main parties.
Political scientists have shown that politicians have an incentive to advance and support polarized positions. Some scholars 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." Other theories claim that 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 that 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 that 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. This allowed wealthy people, corporations, and other groups to push the parties' policy platforms toward ideological extremes, resulting in a state of greater polarization. Other scholars note that this does not necessarily hold true for mass donors to political campaigns. These scholars argue that 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.
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 to 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 Democrat 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 Chavez.
Gerrymandering in the U.S. redistricting process has been linked to the rise in polarization by some political scientists. Some scholars argue that the practice of redistricting creates political polarization by making more homogeneous, ideologically distinct districts. This results in elected representatives who represent more polarized beliefs. According to Carson et al. (2007), this makes it easier for more extreme candidates to win elections (and reelection) as the makeup of the voting block shifts in the direction of a polar extreme. This effect is more modest when analyzed over multiple election cycles and in the United States as a whole. Politically motivated redistricting has been associated with the rise in partisanship in the U.S. House of Representatives between 1992 to 1994. Many political scientists argue that redistricting practices have not played a major role in causing political polarization. The impact of redistricting on political polarization is measurable, but over broad areas and time periods, the effect of redistricting on polarization is found to be minimal.
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 users 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. 
The implications of political polarization “are not entirely clear and may include some beneficial as well as detrimental consequences.” Overall, while the exact effect of political polarization is disputed, it is evident that its implications can alter the character of the political process as well as the political composition of the general public.
As political scientists have shown, political polarization has several important implications for the United States Congress. First, polarization increases gridlock in Congress and lowers the number of moderates in Congress, which limits the amount of legislation passed, decreases bipartisanship and can lead to policy inaction.
Second, scholars have shown that polarization incentivizes members of Congress to use stall tactics and restrictive rules. Polarization has negatively influenced the proceedings of Congress by giving rise to an increase in the use of closed rules on the floor, such as limiting amendments, excluding minority party members from committee deliberations and increased use of the hold on executive and judicial appointments and the filibuster on non-contentious policy issues.
Third, by hampering the policymaking process, polarization lowers the quality of legislation that does get passed. Partisan tactics motivated by polarization decrease transparency, reduce oversight, restrict the ability of the government to deal with long-term domestic issues, especially those that require changing the distribution of benefits and can lead to poor legislation. That being said, other aspects of the political environment, such as hurried action after a national emergency or the influence of money and interest groups, can also lead to poor legislation.
Much of the scholarship on polarization has shown that political polarization leads to less deliberation and cooperation as well as an increase in partisan animosity as the majority party tries to expedite the legislative process in order to pass its agenda. The overarching consequence of a legislative process prolonged by polarized strategies is that there is less coordination between political parties as well as between the House of Representatives and the United States Senate. This limits progress and results in less legislation being passed.
However, some scholars contend that political polarization is not prominent in every legislative matter and does not influence all policy decisions. According to some political scientists, partisan agreement has been the historical trend in Congress and many bills are passed with bipartisan support in the modern era, including ones of political importance. Some studies have shown that approximately 80% of House bills passed in the modern era have had support from both parties.
Opinions among scholars on the implications of polarization on the public are mixed. Some political scientists argue that the growing polarization in government has directly contributed to political polarization in the electorate. Other scholars state that polarized practices in government do not significantly influence the public’s attitudes toward legislators.
On the one hand, some experts argue that polarization can contribute to a decrease in public interest in politics, a decrease in party identification and a decrease in voter turnout. Polarization can alienate citizens, since it encourages confrontational dynamics between parties that lower the public’s trust in government and causes the public to perceive the general political debate as less civil because of the increasingly harsh and ideologically-minded political discourse across television, radio and internet sources.
On the other hand, although voters say that they disapprove of the increasing coarseness of the political environment, some scholars argue that the public has responded favorably to polarization. In the United States, some political scientists assert that elite polarization has galvanized political participation by the mass public as there has been more voting and nonvoting participation, greater engagement and investment in campaigns and increases in positive attitudes toward government responsiveness. In fact, “much of the most persuasive research suggests that negativity, counter to conventional wisdom, stimulates voter turnout no matter how much Americans complain about it.”
Scholarly work has also shown that political polarization can increase party identification and the degree to which voters think positively about their party and stimulate an ideological sophistication of the politically engaged public as party identification becomes increasingly influenced by policy differences of political parties. As parties become more ideologically unified, voters become more knowledgeable about policy positions.
However, some scholars argue that because voters are unaware how polarized their choices have become, they tend to elect more ideologically polarized candidates, which leads to government and legislation that is less representative of the voting public’s desires.
Scholars have also shown that political polarization has implications for mediating institutions, namely the media, elections and political parties. As Mann and Ornstein argue, political polarization and the proliferation of media sources have “reinforce[d] tribal divisions, while enhancing a climate where facts are no longer driving the debate and deliberation, nor are they shared by the larger public.” As other scholars have argued, the media often support and provoke the obstruction strategies used to disrupt the regular order of policy procedures.
Some scholars assert that the media are not disconnected from general public opinion and that media outlets work to remain unpolarized and nonideological in order to appeal to a larger audience base.
Other political scientists argue that in a polarized environment, it is easier for the media and interest groups to inform voters if elected officials are following through on their campaign promises because politicians are forced to take more distinct stances on policy issues. Thus, polarization can facilitate the elucidation of political actions and then help or harm representatives who do not follow through on their undertakings. This increases accountability of politicians to voters, but it can also be detrimental since in some circumstances it is more important for politicians to focus on unexpected or long-standing issues instead of their campaign promises. Overall, “it is generally considered healthy for a democracy to hold officials accountable for pledges they make in election campaigns.”
Similarly, some scholars have argued that a positive consequence of polarization is that it leads to strong and definitive political parties that offer explicit platforms and messages to voters. Giving voters more distinct choices leads to more participation through voting, working on campaigns, expressing opinions to representatives and giving to candidates or particular causes. As polarization reinforces party affiliation and makes policy positions less ambiguous, voters focus more on the differences in substantive policy views of candidates as opposed to personal attributes and voters are more likely to cast policy-oriented ballots. Therefore, some political scientists have found that “the rise of polarization is not necessarily a bad thing for the polity overall” as more differentiated political parties can benefit voters.
Judicial systems can also be affected by the implications of political polarization. For the United States in particular, scholars state that as polarization increases, confirmation rates of judges decrease. In 2012, the confirmation rate of presidential circuit court appointments was approximately 50% as opposed to the above 90% rate in the late 1970s and early 1980s. As parties in Congress have become more polarized, they have increasingly used tools to hinder the executive agenda and aggressively block nominees. Political scientist Sarah Binder (2000) argues, “senatorial intolerance for the opposing party’s nominees is itself a function of polarization.” By blocking judicial nominations, political polarization hinders the implementation of legitimate laws and impedes the confirmation of appellate judges, which results in higher vacancy rates, extended case-processing times and increased caseloads for judges.
Political scientists argue that in highly polarized periods, nominees have become more reflective of the right or the left and less reflective of the moderate voter as “polarization impacts the appointment and ideological tenor of new federal judges.” Polarization influences the confirmation politics of advice and consent and gives partisan presidents greater ability to place immoderate judges on the federal bench, which obstructs the legitimacy of the judicial branch. Political polarization causes support for nominees to come predominantly from the President’s party, which enables the party controlling the executive branch to pull the judiciary more to the left or right of the political spectrum. Thus, some scholars argue that in a polarized environment the ideological implications of approving judges are much greater.
Ultimately, the increasing presence of ideology in a judicial system impacts the credibility of the judiciary. Polarization can generate strong partisan critiques of federal judges, which scholars argue may damage the public’s views of the legitimacy of the courts and the justice system. Consequently, some political scientists argue that because polarization causes confirmations to be more controversial, it decreases the public’s confidence that a judiciary and the law are unbiased and independent of politics.
Aside from domestic matters, scholars note that political polarization can undercut unified agreement on foreign policy and harm a nation’s position in the world. Division on foreign affairs can strengthens enemies, discourage allies and destabilize a nation’s determination.
Political scientists point to two primary implications of polarization with regards to the Foreign policy of the United States. First, when the United States conducts relations abroad and appears divided, allies are less likely to trust its promises and enemies are more likely to predict its weaknesses. Second, elite opinion has a significant impact on the public’s perspective of foreign policy. In contrast to problems such as unemployment, inflation and crime, where elite viewpoints are not as influential, Americans are less informed of overseas engagements. While a difference of viewpoints between political parties is a foundational aspect of a democratic political system, political polarization has exacerbated this divergence as “it was not inevitable that foreign policy would become, as it has, the single most polarizing aspect of American politics.” Subsequently, the United States currently does not have any fundamental agreement on foreign policy and there is a basic discord about the United States’ function in the world.
Some scholars argue that an additional consequence of elite polarization on foreign policy is a more polarized public. This is due to the fact that the general population cannot easily access as much information on foreign affairs as on domestic matters, so it becomes more reliant upon cues from the political elite, which has grown increasingly polarized.
There have long been numerous scholarly debates that argue over the concept of political polarization, both in whether it is valid, and how it can accurately be measured. There are four primary arguments against the validity of political polarization: 1) Limitations of the Two-Party System, 2) Issue Partisanship, 3) Cultural Differences, and 4) Westernized Focuses.
Limitations of the Two-Party System
By solely acknowledging voting patterns, one cannot make an accurate conclusion as to the presence or absence of political polarization, because in the United States, there is a limited number of Presidential candidates in the two-party system. To assume that the majority of voters are mostly or completely in agreement with the plethora of political issues within their party is a false assumption. Despite contrary beliefs, there are many liberal Republicans and conservative Democrats in the U.S. who have differing political beliefs within their parties. However, these voters most often align with their party because of the limited choice of candidates, and to do otherwise (i.e. vote for a Third-Party candidate) is perceived as a waste of time.
Despite various claims that argue American society is more polarized today than leading up to the U.S. Civil War, numerous scholars explain that much evidence shows there is a relatively stable public opinion on the majority of sociopolitical issues. Where the most polarization exists, rather, is in the “hot topic” or “sensitive” issues (e.g. abortion, gay marriage, U.S. involvement in war). Over-reliance on focusing on opinions regarding social issues to draw conclusion about political polarization is not a valid measurement to fully represent the concept.
In regard to views on public policies, Fiorina and Abrams (2008) found virtually no evidence of an increase in wide-spread political polarization over the past thirty years. Nonetheless, many scholars explain that it is not an increase in ideological coherence among individuals which separates them; it is the partisan extremism (i.e. Democrat v. Republican) which eventually separates voters into one party or the other.
Proponents of the cultural differences argument are critical of political polarization because of numerous factors, influences, and demographics. Among voter demographical features, there is much evidence of race, sex, age, and educational attainment as being some of the main influences in voting behaviors. In addition to these factors, geographic region often plays a major role in voting behavior. Lastly, one’s socio-economic status is a reliable predictor for voting behavior. The combination of these factors and influences compel researchers to reconsider the causes of political polarization.
Much like many academic studies, political polarization scholars often are too narrowly focused within one nation and, thus, make broad generalizations regarding the concept from a national study. To have a better picture of the presence or absence of political polarization, scholars must consider widening the scope of their studies to the international contexts.
- Income inequality in the United States#Political polarization
- False dilemma
- Left–right politics
- Two-party system
- Multi-party system
- Polarized pluralism
- Abramowitz, Alan. "Issue Evolution Reconsidered: Racial Attitudes and Partisanship in the U.S. Electorate." The Sociological Quarterly 38.1 (1994): 1-24.
- Clark, Cal, and Alexander C. Tan. "Political Polarization in Taiwan: A Growing Challenge to Catch-all Parties?" Journal of Current Chinese Affairs 41.3 (2012): 7-31.
- Darity, William Jr. (2007) "Economic Inequality and the African Diaspora."
- Frymer, Paul. "Debating the Causes of Party Polarization in America." The Brennan Center Jorde Symposium on Constitutional Law (2011): 335-50.
- Kallis, Aristotle A. Fascist ideology: territory and expansionism in Italy and Germany, 1922-1945. London, England, UK; New York, New York, USA: Routledge, 2000.
- Keefer, Philip and Knack, Stephen, (Mar., 2002) "Polarization, Politics and Property Rights: Links between Inequality and Growth" Public Choice 111(1/2): 127-154.
- 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: 359-72. HeinOnline.
- Nivola, Peter. "Thinking About Political Polarization." The Brookings Institution, Jan. 2005.
- Simon, Sheldon W. (Dec., 1979) "China, Vietnam, and ASEAN: The Politics of Polarization." Asian Survey 19(12): 1171-1188. doi: 10.2307/2643963
- Sisk, Timothy D. (1st Qtr., 1989) "White Politics in South Africa: Polarization under Pressure." Africa Today 36(1): 29-39.
- Sunstein, Cass R. "Deliberative Trouble - Why Groups Go to Extremes." Yale Law Journal 110.71 (2001): 71-120. HeinOnline. Web. 9 Apr. 2013.
- Vincent, Andrew. Modern Political Ideologies. Third edition. Malden, Massachusetts, USA; Oxford, England, UK; West Sussex, England, UK: Blackwell Publishers Ltd., 2010.
- Wiseman, Colin (Dec., 2010). "The Politics of Institutional Change in Venezuela: Oil Policy During the Presidency of Hugo Chávez." The Canadian Journal of Latin American and Caribbean Studies 35(70): 141.
- DiMaggio, Paul; Evans, John; Bryson, Bethany (1 November 1996). "Have American's Social Attitudes Become More Polarized?". American Journal of Sociology 102 (3): 690–755. doi:10.1086/230995.
- 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. doi:10.1086/590649.
- 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.
- 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 978-0-465-03133-7.
- McCarty, Nolan; Poole,, Keith T.; Rosenthal, Howard (2006). Polarized America : the dance of ideology and unequal riches. MIT Press. Cambridge, Mass. ISBN 9780262134644.
- Abramowitz, Alan I.; Saunders, Kyle L. (27 March 2008). "Is Polarization a Myth?". The Journal of Politics 70 (02). doi:10.1017/S0022381608080493.
- Bafumi, Joseph; Shapiro, Robert Y. (27 January 2009). "A New Partisan Voter". The Journal of Politics 71 (01): 1. doi:10.1017/S0022381608090014.
- Hetherington, Marc J. (17 February 2009). "Review Article: Putting Polarization in Perspective". British Journal of Political Science 39 (02): 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.
- Azzimonti, Marina "The political polarization index"
- 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.
- Fiorina, Morris P.; Samuel A. Abrams and Jeremy C. Pope (2006). "Culture War? The Myth of a Polarized America". Pearson Longman. ISBN 978-0-321-27640-7.
- Ura, Joseph Daniel; Ellis, Christopher R. (10 February 2012). "Partisan Moods: Polarization and the Dynamics of Mass Party Preferences". The Journal of Politics 74 (01): 277–291. doi:10.1017/S0022381611001587.
- Abramowitz, Alan I.; Saunders, Kyle L. (August 1998). "Ideological Realignment in the U.S. Electorate". The Journal of Politics 60 (03): 634. doi:10.2307/2647642.
- Galston, William A. (2009). "Political Polarization and the U.S. Judiciary". UKMC Law Review 77 (207).
- Beniers, Klaas J.; Dur, Robert (1 February 2007). "Politicians’ motivation, political culture, and electoral competition". International Tax and Public Finance 14 (1): 29–54. doi:10.1007/s10797-006-8878-y.
- Hirano, Shigeo, Jr.; James M. Snyder & Michael M. Ting (2009). "Distributive Politics with Primaries". Journal of Politics 71 (4): 1467–1480. doi:10.1017/s0022381609990247.
- 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.
- Sartori, Giovanni (1966). "European political parties: the case of polarized pluralism". Political Parties and Political Development.
- 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 (04): 815. doi:10.1017/S0008423908081110.
- Davey, Hampton (1 August 1972). "Polarization and Consensus in Indian Party Politics". Asian Survey 12 (8): 701–716. doi:10.2307/2643110.
- Kaiser, Robert G. (2010). So damn much money : the triumph of lobbying and the corrosion of American government (1st Vintage Books ed. 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.
- Tam Cho, Wendy K.; Gimpel, James G. (1 April 2007). "Prospecting for (Campaign) Gold". American Journal of Political Science 51 (2): 255–268. doi:10.1111/j.1540-5907.2007.00249.x.
- Garner, Andrew; Palmer, Harvey (28 August 2010). "Polarization and Issue Consistency Over Time". Political Behavior 33 (2): 225–246. doi:10.1007/s11109-010-9136-7.
- Mason, L. (9 November 2012). "The Rise of Uncivil Agreement: Issue Versus Behavioral Polarization in the American Electorate". American Behavioral Scientist 57 (1): 140–159. doi:10.1177/0002764212463363.
- 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, IL.
- Dixit, A. K.; Weibull, J. W. (25 April 2007). "Political polarization". Proceedings of the National Academy of Sciences 104 (18): 7351–7356. doi:10.1073/pnas.0702071104.
- Born, Richard (1994). "[Split-Ticket Voters, Divided Government, and Fiorina's Policy-Balancing Model]: Rejoinder". Legislative Studies Quarterly 19 (1).
- Abramowitz, Alan; Kyle Saunders (2005). "Why Can't We All Just Get Along? The Reality of Polarized America". The Forum 3 (2).
- Campbell, David E.; Green, John C.; Layman, Geoffrey C. (1 January 2011). "The Party Faithful: Partisan Images, Candidate Religion, and the Electoral Impact of Party Identification". American Journal of Political Science 55 (1): 42–58. doi:10.1111/j.1540-5907.2010.00474.x.
- LAYMAN, GEOFFREY C.; GREEN, JOHN C. (8 December 2005). "Wars and Rumours of Wars: The Contexts of Cultural Conflict in American Political Behaviour". British Journal of Political Science 36 (01): 61. doi:10.1017/S0007123406000044.
- Brooks, Clem; Manza, Jeff (1 May 2004). "A GREAT DIVIDE?. Religion and Political Change in U.S. National Elections, 1972-2000". The Sociological Quarterly 45 (3): 421–450. doi:10.1111/j.1533-8525.2004.tb02297.x.
- Bhavnani, R.; Miodownik, D. (12 November 2008). "Ethnic Polarization, Ethnic Salience, and Civil War". Journal of Conflict Resolution 53 (1): 30–49. doi:10.1177/0022002708325945.
- Sisk, Timothy D. (1st Quarter 1989). "White Politics in South Africa: Politics under Pressure". Africa Today 36 (1): 29–39. Check date values in:
- Darity, William A. (2009). Howard Dodson & Colin A. Palmer, ed. "Economic Inequality and the African Diaspora". The Black Condition (Michigan State UP). East Lansing, Mich.
- Lombardi, John V. (2004). "Prologue: Venezuela's Permanent Dilemma". In Ellner, Steve; Hellinger, Daniel. Venezuelan politics in the Chávez era: class, polarization, and conflict. Boulder, Colo.: Rienner. ISBN 978-1588262974.
- Yoshinaka, Antoine & Chad Murphy (June 2011). "The Paradox of Redistricting: How Partisan Mapmakers Foster Competition but Disrupt Representation". Political Research Quarterly 64 (2): 435–447. doi:10.1177/1065912909355716.
- Thompson, Dennis F. (February 2004). "Election Time: Normative Implications of Temporal Properties of the Electoral Process in the United States". American Political Science Review 98 (1): 51–64. doi:10.1017/s0003055404000991.
- 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.
- 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.
- Kousser, J (November 1996). "ESTIMATING THE PARTISAN CONSEQUENCES OF REDISTRICTING PLANS - SIMPLY". Legislative Studies Quarterly 21 (4): 521–541. doi:10.2307/440460.
- 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". PS: Political Science & Politics 45 (01): 39–43. doi:10.1017/S1049096511001703.
- 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.
- Yuan, Elaine Jingyan (2007). The New Multi-channel Media Environment in China: Diversity of Exposure in Television Viewing. Northwestern University. ISBN 1109940211.
- Kim, S.J. (2011). Emerging patters of news media use across multiple platforms and their political implications in south korea. Northwestern University.
- 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.
- Epstein, Diana; John D. Graham (2007). "Polarized Politics and Policy Consequences". RAND Corporation.
- 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, D.C.: Brookings Institute. ISBN 978-0815760801.
- Brady, David. W; John Ferejohn & Lauren Harbridge (2006). "Polarization and Public Policy: A General Assessment". Red and blue nation? Volume One: characteristics and causes of America's polarized politics. Washington, DC: Brookings Institution. ISBN 978-0815760832.
- Jones, David R. (March 2001). "Party polarization and legislative gridlock". Political Research Quarterly 54 (1): 125–141. doi:10.1177/106591290105400107.
- Galston, William A. (2006). "Delineating the Problem". Red and blue nation? Volume One: characteristics and causes of America's polarized politics. Washington, DC: Brookings Institution. ISBN 978-0815760832.
- Sinclair, Barbara (2008). "Spoiling the Sausages? How a Polarized Congress Deliberates and Legislates". In Pietro S. Nivola & David W. Brady. Red and blue nation? Volume Two: Consequences and Correction of America's Polarized Politics. Washington, D.C.: Brookings. ISBN 978-0815760801.
- Binder, Sarah A. (Winter 2000). "Going Nowhere: A Gridlocked Congress". Brookings.
- Wilkerson, John D.; E. Scott Adler (2013). Congress and the politics of problem solving. Cambridge [England]: Cambridge University Press. ISBN 978-1107670310.
- Carson, Jamie L.; Finocchiaro, Charles J.; Rohde, David W. (1 October 2010). "Consensus, Conflict, and Partisanship in House Decision Making: A Bill-Level Examination of Committee and Floor Behavior". Congress & the Presidency 37 (3): 231–253. doi:10.1080/07343469.2010.486393.
- Lee, Frances (2005). Paul Quirk & Sarah Binder, ed. The Legislative Branch. New York: Oxford UP.
- Hibbing, John R.; Christopher W. Larimer (2008). "The American Public's View of Congress". The Forum 6 (3).
- Hetherington, Marc J. (2008). "Turned Off or Turned On? How Polarization Affects Political Engagement". In Pietro S. Nivola & David W. Brady. Red and blue nation? Volume Two: Consequences and Correction of America's Polarized Politics. Washington, D.C.: Brookings. ISBN 978-0815760801.
- Dodson, Kyle (1 September 2010). "The Return of the American Voter? Party Polarization and Voting Behavior, 1988 to 2004". Sociological Perspectives 53 (3): 443–449. doi:10.1525/sop.2010.53.3.443.
- Mutz, Diana C. (2006). "How the Mass Media Divide Us". Red and blue nation? Volume One: characteristics and causes of America's polarized politics. Washington, DC: Brookings Institution. ISBN 978-0815760832.
- Rosenstiel, Thomas (2006). "Two Alternative Perspectives". Red and blue nation? Volume One: characteristics and causes of America's polarized politics. Washington, DC: Brookings Institution. ISBN 978-0815760832.
- Brooks, Deborah Jordan & John G. Geer (2008). "Comments on Chapter One". In Pietro S. Nivola & David W. Brady. Red and blue nation? Volume Two: Consequences and Correction of America's Polarized Politics. Washington, D.C.: Brookings. ISBN 978-0815760801.
- Dionne, E.J., Jr.; William A. Galston (14 December 2010). "A Half-Empty Government Can't Govern: Why Everyone Wants to Fix the Appointments Process, Why It Never Happens, and How We Can Get It Done". Brookings.
- Wittes, Benjamin (2008). "Comments on Chapter 3". In Pietro S. Nivola & David W. Brady. Red and blue nation? Volume Two: Consequences and Correction of America's Polarized Politics ([Online-Ausg.] ed.). Washington, D.C.: Brookings. ISBN 978-0815760801.
- McCormick, James M.; Eugene R. Wittkopf (November 1990). "Bipartisanship, Partisanship, and Ideology in Congressional-Executive Foreign Policy Relations, 1947-1988". The Journal of Politics 52 (4): 1077–1100. doi:10.2307/2131683.
- Wilson, James Q. (2008). "Comments on Chapter 4". In Pietro S. Nivola & David W. Brady. Red and blue nation? Volume Two: Consequences and Correction of America's Polarized Politics. Washington, D.C.: Brookings. ISBN 978-0815760801.
- Souva, M.; Rohde, D. (1 March 2007). "Elite Opinion Differences and Partisanship in Congressional Foreign Policy, 1975-1996". Political Research Quarterly 60 (1): 113–123. doi:10.1177/1065912906298630.
- Beinart, Peter (2008). "When Politics No Longer Stops at the Water’s Edge: Partisan Polarization and Foreign Policy". In Pietro S. Nivola & David W. Brady. Red and blue nation? Volume Two: Consequences and Correction of America's Polarized Politics. Washington, D.C.: Brookings. ISBN 978-0815760801.
- Sherkat, Darren (2011). "Religion, politics, and support for same-sex marriage in the United States, 1988-2008".
- Bolzendahl (2005). "Polarization, secularization, or differences as usual? The denominational cleavage in U.S. social attitudes since the 1970s.".
- Van Boven (2012). "Political polarization projection: Social projection of partisan attitude extremity and attitudinal processes.".
- Greenawalt, Kent (1988). Religious convictions and political choice.
- Ansolabehere (2006). "Purple America.".
- Teixeira (2009). The future of red, blue and purple America.
- "U.S. elections: How groups voted in 2012.". 2012.
- Brown (2009). "Voting behavior based on socioeconomic status.".
- Holton (2000). "Globalization's cultural consequences.".
- Pieterse (2009). Globalization and culture: Global mélange.