What are the long-term consequences of the Muhammad cartoon furor? I predict it is helping bring on not a clash of civilizations but their mutual pulling apart. This separation, which has been building for years, has dreadful implications.

Signs of disengagement are all around.

* Trade: Boycotts now exist in both directions. As the American government sanctions Iranian products, Iran’s president, Mahmoud Ahmadinejad, says his government will “revise and cancel economic contracts” with countries where newspapers published the cartoons. Several Muslim countries have suspended trade with Denmark, while Muslim-owned stores in Canada have removed Danish products. The Pakistani medical association even announced a boycott of medicines from five European countries.

* Consumer items: Muslims are increasingly replacing Western consumer items with their own. They purchase the extremely modest Fulla and Razanne dolls rather than the busty Barbie. In France, Beurger King provides halal food, competing with Burger King, just as Mecca Cola takes the place of Coke and Pepsi. Al-Jazeera is starting an English-language channel to go up against CNN and the BBC.

* Financial investments: As a result of freezes on funds and the designation of terrorist entities, Muslims have moved large amounts of capital out of the West and invested it either in their own countries or in other places around the world, such as East Asia. Middle Eastern oil exporters before September 11, 2001, annually put as much as $25 billion into American investments; since then, the amount is about $1 billion a year.

* Emigration: The attacks of September 11 caused a significant increase in obstacles to Muslims traveling to the West, so fewer Muslim business executives, students, hospital patients, conference-goers, and workers are reaching there.

* Tourism: Islamist atrocities such as the murder of 60 Japanese, German, and Swiss tourists in Luxor in 1997 or the abduction of 32 German and other travelers in the Sahara in 2003 led some Westerners to avoid discretionary travel in the Muslim world. Cartoon-related violence has prompted a Danish advisory warning citizens against travel to 14 Muslim countries. Scandinavian tourist companies have canceled many tours to North Africa.

* Foreign aid: Muslim aggression against aid workers in Indonesia, Lebanon, Pakistan, and the Palestinian Authority have led to the partial or complete withdrawal of European missions. In Chechnya, the Danish aid mission was expelled and the Iraqi Transport Ministry has rejected any future offers of Danish reconstruction money.

* Embassies: From the seizure of the American embassy in Tehran in 1978 to the multiple attacks on Danish and other European embassies this month, the assault on Western diplomatic missions in Muslim countries is causing them to take on the features of armed fortresses, to be removed from the center of towns to the peripheries, and in some cases to be closed down.

* Westerners providing services: Zayed University in Dubai fired an American professor, Claudi Keepoz, for distributing the Muhammad cartoons to her students. Rampaging Palestinian Arabs caused the foreign observers staffing the Temporary International Presence in Hebron, or TIPH, to flee the area.

These developments suggest what the prime minister of Malaysia, Abdullah Ahmad Badawi, has called a “huge chasm” between the Muslim world and the West. Or, in the more bellicose wording of the influential Sunni imam Youssef al-Qaradawi, “We must tell Europeans, we can live without you. But you cannot live without us.”

Should the chasm widen, with its concomitant lessening of human interaction, commercial relations, and diplomatic engagement, the Muslim world will likely fall further behind than it already has. As I wrote in 2000, “Whatever index one employs, Muslims can be found clustering toward the bottom – whether measured in terms of their military prowess, political stability, economic development, corruption, human rights, health, longevity, or literacy.”

Disengagement will only worsen the Muslim predicament. Reduced contact with the world’s most modern, powerful, and advanced countries would likely cause Muslims to do even worse in those indexes and lapse deeper into a condition characterized by self-pity, jealousy, resentment, anger, and aggression.

Especially when contrasted with Muslim successes in pre-modern times, these traumatic circumstances help explain the crisis in identity that often causes Muslims to seek solace in radical Islam. For everyone’s sake, it is important that Muslims begin more successfully to negotiate their path to modernity, not to isolation.

Mr. Pipes (www.DanielPipes.org) is director of the Middle East Forum and author of “Miniatures” (Transaction Publishers).