Austria is obviously not facing a threat of the totalitarian kind that was looming in the Weimar Republic in late 1932, but Europeans of all democratic political persuasions would do well not to dismiss Mr Haider's performance as irrelevant. For strident nationalism and right-wing extremism have been making inroads, admittedly much smaller than in Austria, in a number of European Union countries in recent years.
In France, Jean-Marie Le Pen of the National Front took 15 per cent of the popular vote in the first round of last year's presidential election. His party still does not have a seat in the National Assembly, but his candidates have performed strongly enough in recent by-elections to force his democratic opponents of right and left to form a common electoral front to deny him victory.
There have been similar encouraging signs for anti-establishment, anti- immigrant, nationalist parties such as Gianfranco Fini's National Alliance in Italy and the Vlaams Blok in Belgium. Some British Conservatives, while not considering themselves to be in any sense on the extreme right, nevertheless believe the best chance of winning the next election lies in playing the nationalist, anti-European and anti-immigrant cards.
Mr Haider spotted the vote-winning potential of these issues long ago. His opposition to Austria's entry into the EU in January 1995 has blended neatly with his anti-immigrant rhetoric to produce a demagogic message so powerful that it is believed the Freedom Party took 50 per cent of the blue-collar Austrian vote last Sunday.
It should quickly be said that, in terms of political ideas and style, Hitler and Mr Haider are leagues apart. For his part, the Freedom Party leader rejects all comparisons with Hitler as malicious nonsense, although he cannot deny that he had to resign as chief minister of the province of Carinthia in 1991 after he praised the Nazi employment policies of the Thirties.
Mr Haider enjoys the distinction of being Europe's most prominent and successful far-right politician, one whose party stands a real chance of gaining a share of national power after Austria's next general elections scheduled for 1999. Ten years after he took over the Freedom Party and wrenched it from the liberal centre to the extreme right, the party is running neck and neck with Austria's two main political parties, the Social Democrats of Chancellor Franz Vranitzky and the conservative People's Party.
Mr Haider has even upset the apple cart in Vienna, one of the world's great socialist strongholds of this century. Last weekend he shattered the Social Democrats' 51-year unchallenged grip on power in the Austrian capital, where his party took 28 per cent of the vote in regional elections.
It is sometimes said that the far right would not achieved such success over the past 10 years if Austria had made a better job in the post-war years of confronting its Nazi past. Certainly, for most of the post-1945 era, Austrians found it all too convenient to cling to the Allied powers' wartime statement that Austria had become the "first victim" of Nazi aggression when Hitler incorporated it into the Third Reich in 1938.
Unlike Germans, who underwent a tremendous soul-searching about the Nazi period from the late Fifties onwards, Austrians for the most part shied away from painful national self-analysis until quite recently. It is easy to jump to the conclusion that this explains why post-war Germany has never produced a far-right movement of any significance, while Austrians found no difficulty in electing as their president one Kurt Waldheim, a former German army intelligence officer who covered up his war record in the Balkans.
Yet the rise of the Austrian far right under Mr Haider is not simply a matter of history being swept into the national unconscious after 1945 and now bursting out in a putrid flood. Mr Vranitzky, the Chancellor since 1986, did his fellow-countrymen a great service when he visited Israel in 1992 and acknowledged that Austrians had been active participants in Nazi horrors committed against the Jews.
Austria's war record is so fully out in the open these days that even Mr Haider takes care to distinguish his politics from those of the Nazis. "There is not a single parliamentary deputy of the Freedom Party who would identify with the barbarities of the Nazi period ... We clearly distance ourselves from every system which, like that of the National Socialists, disregards human rights," he said in a parliamentary debate last January.
The Austrian far right's strength probably has less to do with history than with present-day conditions; in particular, the dramatic changes forced on Austria by the end of the Cold War and the country's admission to the EU. During the Cold War, international neutrality and internal political calm were essential conditions for Austria to rebuild itself as a prosperous, placid democracy.
But the eastern European revolutions of 1989 and the Soviet Union's collapse in 1991 dispensed with the need for consensus politics in Austria and opened the door for the country to apply for EU membership. These factors quickly injected new and sharp controversies into Austrian politics.
The Social Democrat-People's Party coalition government fell apart last year over budget cuts needed to help Austria qualify for European monetary union in 1999. At the same time, resentment of industrial, financial and agricultural competition in the European single market began to intensify, as did fear of unemployment among traditionally socialist working-class voters.
While the two main parties squabbled and public discontent simmered, Mr Haider was happy to sit back and watch his share of the national vote go up. In last December's general elections, it touched 22 per cent.
Another vital factor in his appeal was his clear-cut anti-immigrant message. Austria lies on the western edge of the former Communist world but, with the exception of extreme crises such as the 1956 Hungarian uprising and the 1968 Soviet invasion of Czechoslovakia, rarely experienced large waves of immigration from the east in Communist times.
That helped to preserve Austrians' self-image as a Western nation, a cut above the peoples to the east. All that has changed since 1989, however, with travellers and illegal immigrants from eastern Europe a far more common sight in Austria than in the past.
To drive the point home to Austrians, it will not be long before their eastern neighbours join the EU. To Haider voters, it must seem that the world is turning upside down, that Austria is about to drown in a sea of cheap labour, unrestricted travel and criminal activity from the poorer, "less civilised" parts of Europe.
Mr Haider's success stems from weaving together the economic fears and nationalist prejudices of lower-middle class and industrial working-class Austrians, and then blaming the EU for everything. He rails against the Maastricht treaty in a way that Teresa Gorman, the anti-European Tory MP for Billericay, would find easy to understand.
It is tempting to interpret the rise of Mr Haider's Freedom Party as evidence that Maastricht, the single European currency and the drive for greater European integration are going to provoke a right-wing nationalist backlash across much of Europe. Practically every EU government is cutting spending and social benefits and raising taxes in order to meet the Maastricht criteria for monetary union, and this at a time when 18 million people are unemployed in the 15 member-states.
It would seem at first sight that only right-wing forces are likely to benefit from the growing strains in European societies caused by this attempt at rapid integration. Communism is finished as a credible ideology, immigration is perceived as a major social problem in many EU countries, and mainstream political parties of left and right have been discredited by a stream of corruption scandals and their apparent ineffectiveness in government.
Yet when painting a broad-brush picture of Europe, it is vital to bear national distinctions in mind. In Germany, for example, the centre-right government's austerity measures have certainly led to protests, but these have come from the opposition Social Democrats and the trades unions rather than from the barely noticeable far right.
Moreover, when the Social Democrats tried to win three Land elections last March on a platform of delaying monetary union, they suffered convincing defeats. In the country that lies at the heart of the European project, there is little sign that either the far right or the mainstream opposition will pick up public support by proclaiming extremist, anti-European slogans.
In France, it seems unlikely that Mr Le Pen will turn out to be the main beneficiary of anti-European social protest. The two-round French voting system has recently shown its effectiveness as a means of keeping Mr Le Pen at bay, by enabling Gaullists, moderate rightists, centrists, socialists and Communists to form a "republican front" in the second round and defeat his candidates.
Last year's presidential election indicated that Mr Le Pen's anti-immigrant message attracted considerable support in some parts of France, notably Alsace and several big cities in the south such as Toulon. Yet the National Front has never shown the kind of nationwide strength that the Austrian Freedom Party is demonstrating, and much of the party's new support in recent years has come from former Communist voters, who represent a declining electoral constituency.
There are several prominent anti-single currency campaigners in the Gaullist camp, notably Philippe Seguin, the speaker of the National Assembly. So far, however, Mr Seguin and his allies have little to show for their efforts to connect public opposition to the government's austerity policies with their own anti-European agendas.
In Italy, the most radical political force on the scene at the moment is the Northern League, whose green-shirted activists may appear in some ways to share common ideological ground with the people who work for Mr Haider. Yet the Northern League is neither anti-European nor anti-Maastricht as such; it is anti-southern Italy.
What the Northern League's leader, Umberto Bossi, says he wants is the secession of prosperous northern Italy and the inclusion of this region in the "hard core" of Europe, the area in which France, Germany and the Benelux countries are planning to adopt the euro in 1999. Mr Bossi regards southern Italy as a drag on the north's ambitions; but whatever his recklessness in calling for Italy's break-up, he can hardly be accused of trying to whip up anti-European hysteria.
In Denmark and Sweden, opposition to closer EU integration has certainly been stoked by a strong sense of nationhood and by suspicions that the EU does too little to foster employment. Yet there is no real connection here with far-right political activity. Indeed, when Sweden held its own European Parliament elections last year, the substantial anti-EU vote was picked up not by parties of the right but by the Greens and by the Left Party, which is made up of former Communists.
The case for a resurgent far right across Europe is therefore far from proven. There are certainly some features on the European landscape, such as high unemployment, social dislocation and an uncertain international political and security climate, that recall the Europe of the Twenties and early Thirties in which Fascism and Nazism were born.
Yet history never repeats itself exactly. Today's far right is not a replica of the far right of that period. It operates within a context of general European prosperity and intellectual acceptance of the virtues of freedom and tolerance that limit its popular appeal.
Moreover, by the very fact that it has already happened, history serves, or should serve, as a kind of alarm system. This was demonstrated by the negative reaction of most informed Europeans to Sunday's election results in Austria. We shall have to see whether the results have scared Austrians enough to produce a backlash against Mr Haider when they next go to the polls.
For the moment, however, we should recognise that the emergence of the Austrian far right reflects conditions that are largely specific to Austria. We outsiders are free to pass comment on Mr Haider, but it is up to the Austrians themselves to do something about him.