What is Extremism?

A simple definition of extremism emphasizes deviations from mainstream beliefs. Yet, in politics, extreme beliefs can quickly become the norm of a party. In this context, the extremism is actually the distance between two sets of normative and mainstream ideologies.

When distributions of beliefs are bimodal in this way, an alternative definition of extremism may be more useful. I suggest that we consider extremism to be the adoption of beliefs without the deliberate or critical processing of information, that sharply deviates from mainstream ideology, that functions primarily to signal loyalty to a group, and which is impervious to change, even in the face of countervailing evidence.

Coalitional Origins

This definition is based on an understanding of humans as a coalitional species that was ancestrally dependent on group memberships for survival. In contexts where resources are limited and survival is not guaranteed, competition between groups is necessitated to gain and maintain control over local resources.

The paradox of this conflict, described by Tooby and Cosmides1, is that it requires a great deal of internal group coordination and cooperation. This makes trust an essential element of group membership. The fear that a member may free ride on the efforts of others, or worse yet, defect to an opposing coalition, is a threat to the preservation of the group.

Trust is enhanced by our ability to clearly demarcate ourselves as members of our group. The stronger the signals the better. Good signals are those which clearly differentiate membership in one group versus another; even stronger are those which are also costly to express, and therefore hard to fake.

Tooby connects this to political beliefs2—arguing that common ground between liberals and conservatives is quickly dismissed, as it provides no means of signaling and solidifying one’s position in a political coalition. The more divergent and stronger beliefs we evince, the more we signal that we can be trusted by our allies. A single misstep might leave us out in the cold—on our own to survive in the political wilderness.  

Shifting Poles

This perspective provides a foundation for understanding why we are drawn to political ideologies that inform a diverse set of beliefs, but why do we see a continued shifting to more and more extreme beliefs?

One explanation may be that it is a response to a perceived threat from the opposing group. Research on stereotype accuracy has demonstrated that political stereotypes tend to be accurate in their general direction, but they are strongly exaggerated.3 The political outgroup is vilified as morally corrupt and homogenous. As a threat is elevated, the need to solidify the moral superiority of one’s own group, as well as one’s allegiance to it, becomes increasingly important. As each political group adjusts in response to the perceived threat, an arms race to the most extreme poles ensues.  

Another explanation rests on a curious pattern that was observed by social psychologists, starting in the 1960s, wherein groups of people discussing a topic would leave the discussion endorsing a position more extreme than the one with which they began.4 One explanation that gained traction was the notion that people strive to identify the group norm and then shift their attitude to converge with it, perhaps even increasing the extremity of their attitude beyond the norm in order to appear as a model group member.5 An iterative process of this sort could quickly produce extreme positions. A shift beyond the group norm may even be rewarded with an increase in personal status owing to a strong signal of commitment to the ingroup.

An alternative explanation offered for group polarization effects suggested that people shift to more extreme positions following discussion because they are exposed to new and persuasive arguments in favor of their current position.5 Some of the strongest evidence in support of the theory showed susceptibility to persuasive arguments even when members were exposed to arguments that favored an opposing position. These findings painted a picture of humans as rational and open-minded consumers of information—capable of reversing course even from an extreme trajectory.

Yet, in a modern era where complex algorithms tailor the content of our searches and newsfeeds to fit our pre-existing preferences and attitudes,6 any chance of exposure to countervailing persuasive arguments is quickly disappearing.

Even more concerning is recent research documenting a back-fire effect in which exposure to contradictory political ideas actually increases polarization.7 This may be owing to our ability, upon hearing contradictory information, to develop strong counter-arguments. At first glance, these findings may seem contradictory to the notion that we can be swayed by persuasive arguments no matter their origin, but a key predictor of attitude change in that research was the perceived validity of the arguments. It seems that our coalitional-colored glasses bias our attitudes so strongly that we quickly dismiss the veracity of outgroup arguments.

Will there be blood?

The political divide in America is certainly sharp, but it may look benign in comparison to the violent terrorism engendered in other contexts. Yet it fosters a political gridlock in which strict adherence to an ideology forbids compromise with one’s adversaries and stalls any hope of progress. Each party plays defense and schemes for control in order to enact a one-sided political agenda that the opposition will swiftly reverse upon the turning of tides. Taken a step further, recent incidences such as the political pipe-bombs sent to high-profile Democrats and critics of President Trump, point to the possibility that our ever-increasing coalitional fervor is setting the stage for violence. Recent data reported that 18% of Democrats and 14% of Republicans indicated they thought violence against the opposing party would be justified (on a scale ranging from “a little” to “a lot”) if the opposing party wins the 2020 presidential election.8 Opinions such as these are extreme, but given our penchant for polarization, they paint a chilling picture of where the chasm in our politics might lead.

Read the full series “Extremism in Historical and Evolutionary Perspective”:

  1. Introduction by Anthony Lopez and Hammad Sheikh
  2. The Virtue of Extremism is its Enhancement of the Ordinary by David Barash
  3. Extremism as Defense by Rose McDermott
  4. Why Extremism Isn’t the Real Issue by Mark Sedgwick
  5. What is Radicalization? by Sophia Moskalenko
  6. Conservative Extremists Are Afraid of Threats That Don’t Exist by Colin Holbrook and Jennifer Hahn-Holbrook
  7. Extremist Violence Has Its Roots in Morality, Not Ideology by Clark McCauley
  8. In the Eye of the Beholder: Parochial Altruism, Radicalization, and Extremism by Zoey Reeve
  9. Hidden Figures: The Untold Story of Terrorist Recruiters by John Horgan and Katerina Papatheodorou
  10. Why Terrorists Are Misunderstood by Max Abrahms
  11. Why Religious Extremism is Maladaptive by Richard Sosis
  12. The Extremist in Historical Perspective: Lessons from the Era of Anarchist Terrorism by Randall Law
  13. Terrorism and the Apocalyptic by Charles B. Strozier
  14. Extremist Groups Require the Greatest Trust Among Members by Melissa McDonald
  15. Moral Rigidity Evolved to Strengthen Bonds Within Groups by Antoine Marie
  16. Sacred Values, Social Identities, and Extremist Violence by Nafees Hamid


1 Tooby, J. & Cosmides, L. (1988). “The Evolution of War and its Cognitive Foundations,” Institute for Evolutionary Studies Technical Report, 88(1).

2 Tooby, J. (2017). “Coalitional Instincts,” Edge. What scientific term or concept ought to be more widely known? Available at: https://www.edge.org/response-detail/27168

3 Jussim, L., Crawford, J. T., & Rubinstein, R. S. (2015). “Stereotype (In)Accuracy in Perceptions of Groups and Individuals,” Current Directions in Psychological Science, 24(6), 490–497. doi:10.1177/0963721415605257

4 Moscovici, S., & Zavalloni, M. (1969). “The Group as a Polarizer of Attitudes,” Journal of Personality and Social Psychology, 12, 125-135.

5 Isenberg, D. J. (1986). “Group Polarization: A Critical Review and Meta-Analysis,” Journal of Personality and Social Psychology, 50(6), 1141–1151. doi:10.1037/0022-3514.50.6.1141

6 Pariser E (2011). The Filter Bubble: How the New Personalized Web is Changing What We Read and How We Think. Penguin: New York.

7 Bail, C. A., Argyle, L. P., Brown, T. W., Bumpus, J. P., Chen, H., Hunzaker, M. B. F., … Volfovsky, A. (2018). “Exposure to Opposing Views on Social Media Can Increase Political Polarization,” Proceedings of the National Academy of Sciences, 115(37), 9216–9221. doi:10.1073/pnas.1804840115

8 Kalmoe, N. P. & Mason, L. (2019). “Lethal Mass Partisanship: Prevalence, Correlates, & Electoral Contingencies,” Presentation at the January 2019 NCAPSA American Politics Meeting. Available at: https://www.dannyhayes.org/uploads/6/9/8/5/69858539/kalmoe___mason_ncapsa_2019_-_lethal_partisanship_-_final_lmedit.pdf

Published On: May 14, 2020

Melissa McDonald

Melissa McDonald

Melissa McDonald is an Assistant Professor of Psychology at Oakland University. She studies the evolved psychology of intergroup conflict, particularly how that function varies between the sexes as a result of an evolutionary history in which men and women faced distinct adaptive challenges in their interactions with outgroups. Her research also investigates the development of practical interventions to reduce bias between groups in real conflict, and large-scale interventions aimed at promoting minority students’ persistence and success in STEM fields.

One Comment

  • Barry Deane says:

    I am not sure that ‘extremist groups require the greatest trust…’. They may simply be bonded through shared dilusions and alienation. Compared even to criminal gangs, rather than our more socially accepted institutions, extremist groups seem to be vulnerable to a suicidal conclusion – a non-terrorist example being the mass suicide by 900 plus members of The People’s Temple at Jonestown Guyana in 1978.

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