Although some scholars have argued that authoritarianism is characteristic only of the right and not of the left, persuasive reasons exist for doubting this claim. Intuitive observation of left-wing and right-wing regimes as well as radical political movements of the left and right reveals 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. In addition, systematic inquiry into the similarities and differences between far-left and far-right radicals in the United States has been hampered by various methodological difficulties. One can list, among these, such problems as the obvious inappropriateness of the F scale (owing to its strong right-wing content) as a measure for identifying left-wing authoritarians; the difficulty of obtaining adequate samples of true believers of the extreme left and right; the self-image of the American left as a persecuted minority which, for reasons of self-interest, spuriously inflates the degree of support expressed by its members for individual rights and liberties; and the exposure of both extreme camps to the liberal democratic values dominating American political culture, which unmistakably colours their political rhetoric.

We have reason to think that a similar study conducted in some – perhaps many – European countries would reveal even greater similarities between the far left and far right than we have turned up in the United States. Unlike the United States, which has enjoyed a strong liberal democratic tradition that has served to weaken and soften the intensity of its radical movements, a number of European countries, less wedded to liberal democratic principles, have developed a more vigorous, less diluted tradition of radical politics. These nations have long had to contend with powerful extremist movements actively and significantly engaged in the political struggles of their respective nations. The radical movements of Europe have been more extreme and zealous – more unequivocally revolutionary and reactionary – than the radical movements of the United States. The sustained confrontation of these extremist movements, in our view, is likely to have intensified the authoritarian propensities of each.

In the present article, through a series of surveys in which we have tried to idenify, as best we can, supporters of the far left and far right, we have systematically compared the two camps on a variety of political and psychological characteristics. We find, in keeping with the conventional view, that the far left and the far right stand at opposite end of the familiar left–right continuum on many issues of public policy, political philosophy and personal belief. They hold sharply contrasting views on questions of law and order, foreign policy, social welfare, economic equality, racial equality, women's rights, sexual freedom, patriotism, social conventions, religion, family values and orientations towards business, labour and private enterprise.

Nevertheless, while the two camps embrace different programmatic beliefs, both are deeply estranged from certain features of American society and highly critical of what they perceive as the spiritual and moral degeneration of American institutions. Both view American society as dominated by conspiratorial forces that are working to defeat their respective ideological aims.

The degree of their alienation is intensified by the zealous and unyielding manner in which they hold their beliefs. Both camps possess an inflexible psychological and political style characterized by the tendency to view social and political affairs in crude, unambiguous and stereotypical terms. They see political life as a conflict between ‘us’ and ‘them’, a struggle between good and evil played out on a battleground where compromise amounts to capitulation and the goal is total victory.

The far left and the far right also resemble each other in the way they pursue their political goals. Both are disposed to censor their opponents, to deal harshly with enemies, to sacrifice the well-being even of the innocent in order to serve a ‘higher purpose’, and to use cruel tactics if necessary to ‘persuade’ society of the wisdom of their objectives. Both tend to support (or oppose) civil liberties in a highly partisan and self-serving fashion, supporting freedom for themselves and for the groups and causes they favour while seeking to withhold it from enemies and advocates of causes they dislike.

In sum, when the views of the far left and far right are evaluated against the standard left–right ideological dimension, they can appropriately be classifled at opposite ends of the political spectrum. But when the two camps are evaluated on questions of political and psychological style, the treatment of political opponents, and the tactics that they are willing to employ to achieve their ends, the display many parallels that can rightly be labelled authoritarian.