The victor of the war on terror is far from clear, the historian Bernard Lewis told a Hudson Institute conference.

The British-born professor of Near Eastern studies at Princeton said Monday that he was “more optimistic about the future of our struggle” in the early 1940s — when the French had capitulated to the Germans, when Stalin was Hitler’s ally, and when America was still neutral — than he is today.

“Hitler would have won under these conditions,” Mr. Lewis said, citing America’s inability to clearly define the war on terror and exactly who its enemy is. The professor, whose vision of the future of the Middle East and knowledge of Islam has guided President Bush’s foreign policy, also cited as challenges the multilateralism that hamstrings America’s ability to fight the war and the strong political opposition to policies designed to defeat the enemy, such as detaining terrorists without trial.

During the darkest days of the fight against Nazism, Mr. Lewis said, he “had no doubt that in the end we would triumph.” He does not “have that certitude now,” he said.

Mr. Lewis told the center-right think tank’s conference on the United Nations that he agrees with a former communist dissident and current Israeli parliamentarian, Natan Sharansky, that the only real solution to defeating radical Islam is to bring freedom to the Middle East. Either “we free them or they destroy us,” Mr. Lewis said.

The contention, especially popular in diplomatic circles, that Arabs aren’t suited to democracy and that the West’s best hope lies with friendly tyrants shows an ignorance of the Arabs’ past and contempt for their present and future, and is “demonstrably absurd in historical terms,” Mr. Lewis said.

Mr. Lewis said a great deal of material exists — from Arabs, from Persians, and from Turks — that can form the basis for democracies in the region. He quoted from a 1786 letter to the king’s court in France from the French ambassador to Istanbul explaining why the Ottoman Empire was slow in making decisions. The ambassador reported that unlike in France, where the king made a decision and that was it, “here the sultan has to consult” and so it “takes time to get things done.”

Mr. Lewis said he places no hope in the United Nations being part of the solution. He “first realized the U.N. was hopeless” after the partition of Palestine, he said. Palestine was a “triviality” compared to the partition of India that took place a year earlier, in 1947, he added. Millions of refugees were created and yet India and Pakistan formed a working relationship and sorted out the problems.

The key difference, Mr. Lewis said, was that “in the partition of India, the U.N. was not involved. “The United Nations failed to act after the Arab states invaded Palestine, and then treated Jewish and Arab refugees differently, leaving problems that remain today, he said.