Defense of democracy depends on pessimists who are not defeatists. It depends on spirited realists such as Jean-Francois Revel. For the first time since 1922, when Mussolini seized power, all of Western Europe is democratic. But Revel fears that democracy could prove to be a brief parenthesis in history because democracy practices intellectual self-disarmament.

Part of the problem is the notion that nations that are merely imperfect have no standing to despise nations that are atrocious. Thus in Holland in 1981, a substantial portion of an opinion sample agreed that the Dutch could not criticize Soviet actions in Poland and Afghanistan "as long as housing conditions in Amsterdam fail to meet the highest standards of modern comfort, as long as women remain exploited and the legal rights of heterosexual married couples are denied to homosexual married couples."

Part of the problem is a reflex for self-delusion. It involves representing defeats as victories. For example, the State Department hailed the building of the Berlin Wall as a victory for the West because it revealed the "insecurity" of the East. Actually the wall, like another "victory," the Berlin Blockade, showed that the Soviet Union could abrogate U.S. rights without fear of serious reprisal.

Revel's new book, "How Democracies Perish," is a catalog of folly, at once hilarious and hair-curling, especially regarding the lingering death of d,etente. Either economic links to the West are unimportant to the Soviet Union, in which case d,etente was even dumber in theory than in practice, or they are important, in which case they should be used for leverage. But what happened when the Soviet Union, showing toward the West's warnings the disdain the warnings deserved, imposed martial law in Poland?

France's prime minister declared that, were the West to retaliate by denying new loans to the Eastern bloc, that would be equivalent to "an economic blockade" and "an act of war." Amazing. There is no bankable economy in Eastern Europe. Poland, especially, is hopelessly in hock to the West and without the ability or intention to repay. Yet it is "an act of war" to refuse to stop the piling of bad loans onto the mountain of bad loans.

George Kennan is a tireless auditor of the errors, as he sees them, of people who regard the Soviet regime as radically unlike other regimes. Ten weeks after the invasion of Afghanistan, he said: "Their immediate objective was purely defensive."

Now, leave aside the question of what the Soviet Union had to fear from the communist regime in Kabul that the invading Soviet forces replaced. But what if what Kennan says is true? What does it say about the possibility of d,etente with a regime that says its vital interests are incompatible with an imperfectly attuned communist regime in Afghanistan, an independent trade union in Poland and an Anatoly Scharansky outside prison walls?

When Cambodian communists buckled down to the drudgery (the work of idealists is never done) of murdering three million Cambodians, the communists almost certainly suffered horribly from blisters on their palms, a result of using clubs in what Revel calls "an orgy of exploding skulls." It was like the killing of baby seals, except the killing of the seals evokes more protests, and does not result in movies deflecting the blame from the seal-killers.

A new movie, "The Killing Fields," earns the "Blame America First" Oscar by preaching (it is nothing if not preachy) that communists killed millions but the blame falls on -- hey, you peeked -- America. Why? Because American bombing of the communists drove them crazy. And you thought you had seen every wrinkle in the insanity defense? This version is: The guilty party is the one that deranges the killer by resisting him.

But as Revel notes, genocide can be discreet: "At a time when the entire world was anathematizing the war in Vietnam, an almost flawless program of genocide was being carried out in total secrecy a few thousand kilometers away on the same continent." The killers of millions of Tibetans were Chinese. One Tibetan had this experience: "Accused of having failed to stack the corpses correctly, he was forced to go down into the pit, where he sank into the heap of decomposing flesh. He was hauled out just in time to avoid asphyxiation."

America's conservative president refers to the regime responsible for killing the Tibetans as "so-called Communist China." Ponder that phrase. It is a symptom of the syndrome by which democracies perish.