First, he explains that he will not look outside Europe - an even more unfortunate decision than the neglect of the colonial dimension in his work on the French Revolution. For a long while, Communism was distinguished from social democracy by its greater ability to win a following in what used to be called the Third World.
And, within Europe, French Communism is treated as representative of the European case, with little on the Italian Communists. Though the book mounts a critique of what it sees as the Communists' manipulation of anti- fascism, there is practically nothing on the way that their role in the partisan and resistance movements of the Second World War served to legitimate Communist discipline and militancy.
This book often echoes Cold War diatribes against Communism yet, despite its length, it omits several crucial lines of criticism. The author's concern is with the interior logic of Communism, with too little on how Communists negotiated real-world constraints. There are many well-merited attacks on Communist crimes and mistakes, but the concepts used to explain them are inadequate.
The key term for Furet is totalitarianism, which leads him to the familiar observation of the many parallels between Communist and fascist regimes. Those most committed to this concept usually stress that the totalitarian regime exercised such extraordinary power that it could only be successfully opposed from without - as Nazism was. Yet post-Stalinist reform Communism in its Czech, Polish and ultimately Russian forms is a problem for this approach. Although Furet's book was written in 1993, it does not really explain why the "illusion" it addresses really "passed".
The economic successes of Hitler, and the Soviet Union's distinctive mixture of success and failure, are not discussed. Yet they had large implications for the success of the Nazi and Communist ideas. If Germany had remained wracked by economic misery after 1933, then the Nazi order might well have been less dynamic. Likewise the apparent successes of Stalin's forced industrialisation boosted the "Communist idea" and Soviet military capacity, but stored up problems for the future. Furet barely refers to the limitations of the Soviet-style command economy and neither the name nor ideas of Friedrich von Hayek, its Nobel-winning critic, are to be found in it.
Furet rightly observes that Communism was a secular religion. But this meant that its promises had a this-wordly character, which could be tested by results. Hayek predicted that the Soviet economy would not be able to deliver a sophisticated array of consumer goods. When he turned out to be right, this began to undermine faith in the system and to weaken the appeal of the reform Communists.
However, Furet goes too far when he writes that Communism allowed nothing of value to be created. This attitude, so prevalent at the time he was writing, led to highly destructive consequences in the former Communist countries. The Communist order had subsidised the collective provision of housing, education, health and culture. The sudden removal of these structures created great hardship and wiped out significant resources.
Furet also stresses the anti-bourgeois character of both Nazism and Stalinism. This argument leads to a revision of his own celebrated revisionism - his challenge to the thesis that the modern world was the product of a "bourgeois revolution", in which the capitalist middle classes settled account with feudalism. Furet, following in the footsteps of the English historian Alfred Cobham, was able to show that aristocrats and declasse petty bourgeois, not the true bourgeois, played the key roles in the French Revolution.
Yet here the bourgeoisie makes a comeback. It may not have led the French Revolution, but it is revealed as the hero of modern history and the animating force of non-totalitarian social orders. Its defeats open the way to the disasters of our century - above all those associated with Hitler and Stalin. Furet generally overdoes the parallel between the two dictators in this respect: a sizeable layer of the German bourgeoisie came to quite comfortable terms with the Nazi regime.
There is also evidence that the Communist regimes of Eastern Europe did eventually produce their own "bourgeois" functionaries engaged in capitalist accumulation. Unfortunately, this bourgeoisie is often more notable for pillage and corruption than productive exertion - a pattern far from unknown in earlier phases of Western history.
Furet is far more interested in political structures and ideology than in economics. He wants to explain the deformations produced by the escalating role of terror in what Eric Hobsbawm has called The Age of Extremes. Commendably, Furet starts his story with the First World War, which he sees as fuelling a nihilist rage against the bourgeois order. Its terrible slaughters did brutalise leading fascists and Communists.
Having drawn attention to the Great War's pernicious impact, it is curious that he can still describe the novelty of Stalin and Hitler as a lack of respect for the tradition in which "international rivalries and even conflicts were contained by means of membership in the same European civilisation".
The restraint exercised by such membership had broken down in 1914. Anyway, it offered little protection to colonial peoples.
Stalin's purges and Hitler's exterminations represented a further escalation, but they owed something to earlier demonstrations of wholesale violence. The dismal colonial record of the Western democracies also helped to obscure the secretive massacres of the dictators.
Though Russia was a sort of empire, the "Communist idea" did include black rights and colonial liberation. And, notwithstanding its racism, Nazism attracted some followers in the Middle East and India. The historical understanding must surely seek to grasp what was attractive in these doctrines, as well as what was repulsive.
Though disappointing, this book still contains many passages of real interest. But there is too little that reflects Furet's considerable attainments as an historian - and, perhaps, too much by way of recantation of his own earlier Communist faith.
Robin Blackburn is the author of "The Making of New World Slavery" (Verso)