As America debates immigration policy, it’s instructive to observe the very different immigration debate going on in Europe.

One of the most articulate critics of Europe’s immigration policy, especially toward Muslim immigrant communities, spoke recently in Philadelphia at a conference on Islam and the West sponsored by the World Affairs Council. Aayan Hirsi Ali is an elegant, Somalia-born member of the Dutch parliament who always travels with bodyguards because she is under constant death threat. The reason: her strong critique of radical Islam and the European policies that help it grow.

Hirsi Ali speaks softly, but her words are uncompromising. “In Europe, there is a tendency to appease radical Muslims,” she says. “We have forgotten how to draw the line.”

This is no right-wing diatribe. The Dutch legislator defies political stereotypes – though she belongs to a party of the right, her political support cuts across party lines. Her goal is to goad the Dutch and a global audience to think about crucial topics from which polite people often shy away.

The educated daughter of a Muslim Somali intellectual, she fled an arranged marriage and sought asylum in the Netherlands. Working for social-service agencies, she saw the hidden plight of many Muslim immigrant women in Holland – battered, forced to undergo ritual circumcision, sometimes killed for crimes of honor (when family members suspected them of sexual impropriety).

She wrote an 11-minute film called “Submission, Part 1” about violence against women and Koranic verses that could be used to justify this. Theo van Gogh, the film’s director, was subsequently murdered by a Dutch-born Islamist of Moroccan descent.

Hirsi Ali had to go into hiding. But she later entered politics and continues to call for reforms within Islam, and for immigration reforms. She lives in constant danger: two tall bodyguards hovered wherever she moved in the conference hall.

Her message is twofold: Muslims must openly debate why their religion has provided justification for acts of terrorism. And Europeans need to debate why they have failed so badly at assimilating immigrant communities, especially those that practice Islam.

Unlike the United States, Europe never had a culture of assimilation where second-generation immigrants become hyphenated Europeans. European immigrants often wind up segregated in slums, living on welfare, not speaking the language of their new country.

In part, says Hirsi Ali, the problem is economic. Europe’s regulated economies prevent immigrants from working their way up the economic ladder. “In the United States,” she says, “an immigrant can start a nail shop, and save money. In the Netherlands, you need a diploma to open a nail shop and you must navigate 1,001 rules and regulations. So migrants go on welfare, which kills your dignity and makes you resentful.”

Hirsi Ali also blames Europe’s immigrant problem on concepts of European tolerance that have gone too far. Memories of the Holocaust made Europeans especially sensitive to the stigmatization of any group. “We never want to draw distinctions between us and the other,” says Hirsi Ali, “but in the process we went overboard. For example, we don’t register the number of honor killings (in Muslim communities), because we don’t want to stigmatize any group. We don’t keep records of (immigrants by) ethnicity or religion.”

Until recently, this effort at tolerance led policymakers to ignore the serious problems within some of their Muslim communities – from the preachings of radical imams to repression of women to the teaching of radical Islamist ideas to children.

Hirsi Ali also blames misplaced tolerance for confusing Europeans about how to react to the Danish cartoons that satirized the Prophet Muhammed. For her the issue is clear – Europeans value free speech and separation of church and state, and immigrants must learn to accept those values if they want to be part of their adopted country. That is the line she wants Europeans to draw.

“We fought for centuries for those values,” she says. “These are cultural achievements and we must defend them. This has nothing to do with disrespect for someone’s religion.”

What’s so fascinating about Hirsi Ali is that she speaks as a Dutchwoman of Somali descent. A Somali-Dutchwoman. For us, this concept of ethnic hyphenation seems so commonplace as to be unremarkeable. Europeans are struggling to accept it, and to learn the limits of tolerance in our times.

Trudy Rubin is a columnist and editorial-board member for The Philadelphia Inquirer.