The horseshoe
that isn’t.

Horseshoe theory is less a doctrine than a picture: bend the familiar left–right line until its two ends curl toward each other, and the far left and the far right end up nearer to one another than either is to the centre (Faye, 1972; Choat, 2017). The picture is memorable. An argument needs more.

Stripped down, the theory makes three claims, and none of them is quite the same as the others. The first is resemblance: people at the two extremes think and behave alike — rigid either/or categories, conspiratorial suspicion, hostility toward opponents, impatience with the restraints of democratic politics (McClosky & Chong, 1985). The second is convergence: the movements themselves are said to converge, sharing enemies, grievances and sometimes programmes, so that the extremes are alike not only in style but in substance. The third is circularity: the spectrum is not a line at all but a closed curve, so that “far left” and “far right” are neighbouring positions rather than opposites.

The claims are testable in different ways. Resemblance is a psychological hypothesis about people; convergence is a claim about ideology and policy; circularity is a claim about the shape of political space. Evidence for the first is often passed off as evidence for the second, and the third is usually assumed rather than argued. That is where the theory gets its force — and where it is most vulnerable.

Straight spectrum Bend it

The theory’s history matters because its job kept changing. A metaphor about one broken parliament became a general claim about the psychology of extremism, and then a shortcut in political argument.

1. 1950

   The post-war argument over totalitarianism was gathering force when The Authoritarian Personality made authoritarianism a measurable syndrome, and a disposition associated with fascism (Adorno et al., 1950).

2. 1954

   Hans Eysenck reported that the “tough-minded” personality he tied to authoritarianism appeared among both Communists and fascists — an early empirical version of the resemblance claim (Eysenck, 1954).

3. 1960

   Seymour Martin Lipset’s Political Man treated extremism as a general possibility rather than a right-wing monopoly; one chapter was titled “‘Fascism’: left, right and center” (Lipset, 1960).

4. 1972

   Jean-Pierre Faye published Langages totalitaires, a study of the language of totalitarian regimes from Nietzsche and Marx to Hitler and Stalin. In it the horseshoe describes the position of the German parties of 1932, from the Communists to the Nazis (Faye, 1972).

5. 1985

   Herbert McClosky and Dennis Chong compared left-wing and right-wing radicals in the United States and found “striking parallels” in their political style — the strongest early evidence for the resemblance claim (McClosky & Chong, 1985).

6. 1996–2017

   Faye returned to the history of ideologies in Le Siècle des idéologies (Faye, 1996), and the old image was picked up again by commentators; by 2017 Simon Choat could call it “an increasingly popular notion” and write a rebuttal (Choat, 2017).

7. 2025

   The theory returned to the news twice: a Brown University brain-imaging study reported similar neural processing among extreme left and right participants (de Bruin & FeldmanHall, 2025), and a 43-country analysis found populist attitudes rising toward both ends of the ideological scale (Tamaki & Jung, 2025).

None of these episodes proved the theory. Each generation rediscovered the image because it explained a different discomfort: the collapse of the Weimar centre, the authoritarian temptation inside mass democracy, the strange alliances of the 2010s, the neuroscience of outrage. The horseshoe travelled because it was useful, not because it was demonstrated.

The strongest case for the horseshoe does not rely on the insult. It rests on four kinds of evidence — political style, physiology, mass attitudes and the authoritarian personality — and every one of them is worth taking seriously.

Style

The classic study is Herbert McClosky and Dennis Chong’s comparison of left-wing and right-wing radicals in the United States (McClosky & Chong, 1985). They found “striking parallels in their styles of political engagement, their reliance upon force, their disdain for democratic ideals and practices and their violations of civil liberties”. Both camps, the article reports, saw politics as a struggle between “us” and “them” in which compromise was capitulation. That is a claim about temperament, not policy — and it was made forty years before the current revival.

Physiology

In 2025 a Brown University team put 44 people in an fMRI scanner and showed them a politically charged video (de Bruin & FeldmanHall, 2025). Half leaned left, half right, and most were at the extreme end of their own side. Extreme participants showed heightened activity in regions tied to emotional processing — the amygdala, the periaqueductal grey, the posterior superior temporal sulcus — and similar patterns of neural synchrony to one another, including in a region tied to social cognition. The effect was strongest during inflammatory language; moderates responded more variously. The authors call it evidence for horseshoe politics.

Mass attitudes

The same shape appears in survey data. Eduardo Ryô Tamaki and Yujin J. Jung pooled the fifth wave of the Comparative Study of Electoral Systems — 43 countries and 52 elections between 2016 and 2021 — and found that populist attitudes rise toward both ends of the left–right scale (Tamaki & Jung, 2025). Both extremes arrive at that anti-elite, people-centred posture by different roads.

The authoritarian personality, revised

The oldest strand is the most direct. Hans Eysenck reported in 1954 that Communists and fascists both scored high on “tough-mindedness”, the trait he linked to an aggressive and dogmatic style (Eysenck, 1954). The finding was contested, but the question never went away. In 2018 Lucian Conway and colleagues built a left-wing authoritarianism scale to parallel the right-wing version and found that it correlated with prejudice, dogmatism and attitude strength much as the right-wing scale did (Conway et al., 2018). In 2022 Thomas Costello and colleagues went further: a 39-item scale with three dimensions — anti-hierarchical aggression, anti-conventionalism and top-down censorship — predicted aggressive behaviour toward political opponents and correlated with support for political violence in a representative US sample (Costello et al., 2022). Left- and right-wing authoritarians, they found, share a constellation of traits — social uniformity, prejudice, coercion, aggression, moral absolutism — while differing on others: left-wing authoritarians score lower on dogmatism and cognitive rigidity and higher on negative emotionality.

Put together, the evidence supports a real and specific claim: authoritarianism is not a right-wing possession, and the political style it produces — dogmatic, anti-pluralist, drawn to coercion — can be found at both ends. The strongest proponents do not need to claim that the programmes are identical, only that the psychology and the posture rhyme. On that narrower claim, the horseshoe has a case.

The case against the horseshoe is not that the similarities are imaginary. It is that they are the wrong kind of similarity: real at the level of temperament, misleading at the level of politics, and absent at the level of the geometry the metaphor asserts.

Four objections do most of the work.

The theory also does political work that its evidence cannot support. Choat’s argument is that the horseshoe lets centrists discredit the left while avoiding the question of their own complicity with the far right — which is why the image did so much work in commentary about Jeremy Corbyn, Jean-Luc Mélenchon and Bernie Sanders (Choat, 2017). “It is patently absurd,” he writes, “to compare Stalin to present-day leftists like Mélenchon or Corbyn.”

The empirical test is unkind too. Nonna Mayer compared the voters of Jean-Marie Le Pen and Olivier Besancenot in the 2007 French presidential election and found that they did not occupy the same political space, did not share a social background and did not hold the same values (Mayer, 2011). That is the convergence claim tested directly, and it fails.

What remains is a resemblance at the level of style: real, measurable, and much thinner than the theory needs. Style does not produce convergence, and neither produces a circular political space. The horseshoe is a metaphor that outran its evidence.

Horseshoe theory is argued as one idea. Empirically it is four: shared psychology, shared tactics, shared ideology, shared people. The studies disagree.

The first row is the most contested. Stone (1980) called left-wing authoritarianism a myth; Altemeyer (1996) found very few authoritarians on the left. Newer scales answer that objection without settling it: a comparison of party activists found heterogeneity inside both extremes and concluded it is “erroneous to consider members of extremist groups as being ‘all alike’” (Van Hiel, 2012). The asymmetry camp — rigidity as distinctively right-wing — remains a live rival (Jost et al., 2003).

Two measurement problems recur. Extremists are a small share of any sample, so estimates are fragile; and “extreme” is often measured as distance from the centre, which confounds position with intensity. Populist attitudes rise toward both ends (Tamaki & Jung, 2025), but that is about anti-elite style, not what left and right programmes contain. The evidence supports a family resemblance at the authoritarian end — and little else.

A single left–right line compresses at least two arguments into one number: who controls the economy, and how much social conformity the state should enforce.

Hans Eysenck had already found that political attitudes need more than one dimension (Eysenck, 1954). Seymour Martin Lipset noticed the case a single line cannot hold: working-class voters who were economically left but socially authoritarian (Lipset, 1960). Stanley Feldman’s account treats authoritarianism as a demand for conformity and order rather than a position on property (Feldman, 2003).

Once the axes are separated, the horseshoe stops being mysterious. Hetherington and Weiler sort Americans by a “fixed” versus “fluid” worldview that cuts across party and economics (Hetherington & Weiler, 2018); Norris and Inglehart model authoritarian populism on a cultural axis as well as an economic one (Norris & Inglehart, 2019).

Authoritarian left Authoritarian right Centre Libertarian left

The authoritarian left and the authoritarian right are neighbours in that plane — but only along the top edge. On the economic axis they remain far apart: one wants to socialise property, the other to protect a hierarchy of owners and insiders. The horseshoe appears when a one-dimensional line is forced to follow the authoritarian boundary; the economic extremes are dragged together and the ends curl. That is a projection artifact, not a discovery about the ends.

The older authoritarian-personality tradition read authoritarianism as a right-wing syndrome (Adorno et al., 1950), and Altemeyer’s scale was built on that assumption (Altemeyer, 1996). The two-axis model does not deny that authoritarianism is more common on the right. It denies that it is definitionally right-wing — which is exactly what makes a shared authoritarian style possible without shared politics.

Horseshoe theory largely fails: it is right that authoritarianism appears at both extremes, and wrong that the extremes therefore resemble each other or meet.

What survives

Something real survives, and it is worth naming precisely. Authoritarian dispositions are not monopolised by one side: left-wing authoritarianism is measurable, predicts aggression and correlates with participation in political violence (Costello et al., 2022). Anti-elite populist attitudes rise toward both ends of the spectrum (Tamaki & Jung, 2025). The same mechanisms can radicalise activists of very different ideologies toward violence (McCauley & Moskalenko, 2017).

What follows is not moral equivalence. It is that the danger to liberal politics is a style of politics — hostility to dissent, relish for enemies, faith in a leader or a cause — which can wear either colour. The theory’s origin hints at why the image endures. Faye used the horseshoe to describe the position of German parties in 1932 (Faye, 1972). That was a claim about a particular crisis, not a law of politics. Used as a law, it flatters the centre and insults the left, turning a shared temptation into a shared identity.

The stronger conclusion is the smaller one. Authoritarianism deserves the name wherever it appears; ideological kinship does not follow from a shared appetite for order. Judge movements by what they do to dissent, not by where they sit on a line.

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