The theory is attributed to French philosopher and writer Jean-Pierre Faye. Proponents point to a number of similarities between the far-left and the far-right, including their supposed propensity to gravitate to authoritarianism or totalitarianism. Several political scientists criticize the theory.
The horseshoe metaphor was used as early as during the Weimar Republic to describe the ideology of the Black Front.
Later use of the term in political theory is seen in Jean-Pierre Faye's 2002 book Le Siècle des idéologies (The Century of Ideology). Faye's book discussed the use of ideologies (pointing out that "ideology" is a pair of Greek words that were married in the French language) rooted in philosophy by totalitarian regimes with specific reference to Hitler, Nietzsche, Stalin and Marx.
Others have attributed the theory as having come from the American sociologists Seymour Martin Lipset and Daniel Bell, as well as the Pluralist school. Because the theory is also popular in Germany, a co-contributor to this theory is said to be the German political scientist Eckhard Jesse.
In a 2006 book, American political scientist Jeff Taylor wrote: "It may be more useful to think of the Left and the Right as two components of populism, with elitism residing in the Center. The political spectrum may be linear, but it is not a straight line. It is shaped like a horseshoe." In the same year, the term was used when discussing a resurgent hostility towards Jews and new antisemitism from both the far-left and the far-right.
In a 2008 essay, Josef Joffe, a visiting fellow at the conservative think tank the Hoover Institution, wrote:
Will globalization survive the gloom? The creeping revolt against globalization actually preceded the Crash of '08. Everywhere in the West, populism began to show its angry face at mid-decade. The two most dramatic instances were Germany and Austria, where populist parties scored big with a message of isolationism, protectionism and redistribution. In Germany, it was left-wing populism ("Die Linke"); in Austria it was a bunch of right-wing parties that garnered almost 30% in the 2008 election. Left and right together illustrated once more the "horseshoe" theory of modern politics: As the iron is bent backward, the two extremes almost touch.
In 2015, reformist Muslim Maajid Nawaz invoked the horseshoe theory while lamenting a common tendency on the far-left and far-right towards the compiling and publishing of "lists of political foes," adding:
As the political horseshoe theory attributed to Jean-Pierre Faye highlights, if we travel far-left enough, we find the very same sneering, nasty and reckless bully-boy tactics used by the far-right. The two extremes of the political spectrum end up meeting like a horseshoe, at the top, which to my mind symbolizes totalitarian control from above. In their quest for ideological purity, Stalin and Hitler had more in common than modern neo-Nazis and far-left agitators would care to admit.
In a 2018 article for Eurozine titled "How Right Is the Left?", Kyrylo Tkachenko wrote about the common cause found recently between the far-left and the far-right in Ukraine:
The pursuit of a common political agenda is a trend discernible at both extremes of the political spectrum. Though this phenomenon manifests itself primarily through content-related overlaps, I believe there are good reasons to refer to it as a red-brown alliance. Its commonalities are based on shared anti-liberal resentment. Of course, there remain palpable differences between far left and the far right. But we should not underestimate the dangers already posed by these left-right intersections, as well as what we might lose if the resentment-driven backlash becomes mainstream.
