It is easy to damn the 1930s appeasers of Hitler — such as Stanley Baldwin and Neville Chamberlain in England and Edouard Daladier in France — given what the Nazis ultimately did when unleashed. But history demands not merely recognizing the truth post facto, but also trying to reconstruct the rationale of something that now in hindsight seems inexplicable.

Appeasement in the 1930s was popular with the European public for a variety of reasons. All of them are instructive in our hesitation about stopping a nuclear Iran, or about defending the right of Western newspapers to print what they wish — or about fighting radical Islamism in general.

First, Europe had nearly been destroyed during the Great War, a mere 20 years prior. No responsible postwar leader wished to risk a second continental bloodbath.

Unfortunately, Hitler understood that all too well. In a game of diplomatic chicken, he figured many responsible democratic statesmen had more to lose than he did, as the weaker and once-beaten enemy.

British intellectuals, like European Union idealists today, wrote books and treatises on the obsolescence of war. Conflicts were supposedly caused only by rapacious arms merchants and profiteers at home, not by anti-democratic dictators who interpreted forbearance as weakness. Winston Churchill was a voice in the wilderness — and demonized as a warmonger and worse.

Today, the 50-year Cold War is over, and Europe is at last free of burdensome military expenditure and the threat of global annihilation. Like Osama bin Laden, Iranian President Mahmoud Ahmadinejad senses a certain weariness in much of the West as it counts on perpetual peace.

He assumes that most sober Westerners will do almost anything to avoid military confrontation to stop a potential threat — even though, unlike Hitler, Ahmadinejad not only promises to liquidate the Jews but reveals his method in advance by seeking nuclear weapons.

Some naive conservatives in pre-war Europe thought the German and Italian fascists would prove a valuable bulwark against communism, and so could be politically finessed. So, too, it has been at times with Islamic fascism. Arming the mujahadeen in Afghanistan, Pakistan or Saudi Arabia was once seen as an inspired way of thwarting Soviet communist imperialism.

At the time of the Ayatollah Khomeini's homicidal fatwa against Salman Rushdie, religious conservative commentators from Patrick Buchanan to New York's Cardinal O'Connor attacked Rushdie, rather than defend the Western right of free expression. Apparently, they felt such Islamic threats to supposed blasphemers might have positive repercussions in discouraging left-wing anti-Christian attacks as well.

In the 1930s, the doctrine of appeasement fobbed off responsibility of confronting fascism onto the League of Nations. Both France and England were quiet about the 1936 Italian invasion of Ethiopia and the German militarization of the Rhineland. They counted on multilateral action of the League, which issued plenty of edicts but marshaled few troops.

Likewise, the moral high ground today supposedly was to refer both the Iraqi and Iranian problems to the United Nations. But considering the oil-for-food scandals and Saddam's constant violations of U.N. resolutions, it is unlikely that the Iranian theocracy has much fear that the Security Council will thwart its uranium enrichment.

As fascism spread, France worked on fortifying its German border with the Maginot Line, Oxford undergraduates voted to refuse "in any circumstances to fight for King and Country," and British newspapers decried the Treaty of Versailles for unduly punishing Germany. This was all long before the "no blood for oil" slogan and Al Gore in Saudi Arabia apologizing to his Wahhabi hosts for the supposed American maltreatment of Arabs.

But deja vu pertains not just to us, but our enemies as well. Like the Nazi romance of a exalted ancient Volk, the Islamists hearken back to a mythical purity, free of decadence brought on by Western liberalism. Similarly, they feed off victimization — not just recent defeats, but centuries-old bitterness at the rise of the West. Their version of the stab-in-the-back Versailles Treaty is always the creation of Israel.

Just as Hitler concocted incidents such as the burning of the Reichstag to create outrage, Islamist leaders incite frenzy in their followers over a supposed flushed Quran at Guantanamo and several inflammatory cartoons, some of them never published by Danish newspapers at all.

Anti-Semitism, of course, is the mother's milk of fascism. It is always, they say, a small group of Jews — whether shadowy cabinet advisers and international bankers of the 1930s, or the manipulative neoconservatives and Israeli leadership of the present — who alone stir up the trouble.

The point of the comparison is not to suggest that history simply repeats itself, but to learn why intelligent people delude themselves into embracing naive policies. After the removal of the Taliban and Saddam Hussein, the furious reply of the radical Islamist world was to censor Western newspapers, along with Iran's accelerated efforts to get the bomb.

In response, either the West will continue to stand up now to these recurring post-Sept. 11 threats, or it will see the bullies' demands only increase as its own resistance weakens. Like the appeasement of the 1930s, opting for the easier choice will only guarantee a more costly one later on.

Victor Davis Hanson is a classicist and historian at the Hoover Institution, Stanford University. Reach him at author@victorhanson.com.