There is an American tradition of responding to threats by confusing thoughts with acts and temporarily forgetting what Jefferson set down, in 1779, as one of the country’s founding principles: “that truth is great and will prevail if left to herself, that she is the proper and sufficient antagonist to error, and has nothing to fear from the conflict, unless by human interposition disarmed of her natural weapons, free argument and debate.” The modern legislative history of banning undesirable opinions from American shores began in 1918, when Congress passed the Anarchist Act, which was designed to keep out people with subversive ideas. In 1952, as the McCarthy era was reaching its hysterical phase, the Immigration and Nationality Act, better known as McCarran-Walter, added Communists to the list of aliens to be excluded from entry. In the following years, Graham Greene, Gabriel García Márquez, Pablo Neruda, and Dario Fo were denied visas.

In the age of terror, the Patriot Act denies entry to anyone who materially supports a terrorist organization, which is defined in hopelessly broad terms as any group of two or more people who intend to kill or inflict harm upon others. Among many thousands of foreigners, the law has kept out the Swiss-Egyptian scholar Tariq Ramadan. Ramadan is a grandson of the founder of the Muslim Brotherhood and is an Islamist himself. He argues for a large role for religion in Arab-Muslim states and an assertion of Muslim identity alongside citizenship in Western democracies. (Some critics accuse him of concealing more radical views; their evidence is thin.) His lectures and his books on Islam and the West have gained him a following among young European Muslims. In 2004, Ramadan was given a tenured appointment at the University of Notre Dame. He had rented a house in South Bend, shipped his furniture there, and enrolled his children in Indiana schools, when the State Department, acting on secret information from the Department of Homeland Security, revoked the visa that it had granted him. It has taken two years of repeated applications and inquiries, as well as a lawsuit by American civil-liberties, academic, and literary organizations, for Ramadan to receive an official explanation: between 1998 and 2002, he donated about seven hundred and seventy dollars to a pro-Palestinian French charity that was suspected of channelling money to Hamas, and which did not appear on the State Department’s blacklist until 2003. Ex post facto, Ramadan has run afoul of the Patriot Act.

It’s hard to shake the suspicion that what has really kept Ramadan out is his ideas. State and Homeland Security have interpreted the language of the Patriot Act so loosely that, according to official documents released under the Freedom of Information Act, anyone who is guilty of “irresponsible expressions of opinion” can be refused entry to the United States. In this climate, the American Civil Liberties Union reports, the government has recently denied, delayed, or revoked visas to a group of seventy-five South Korean farmers and trade unionists opposed to a free-trade agreement; a Marxist Greek academic; a Sri Lankan hip-hop singer, whose lyrics were deemed sympathetic to the Tamil Tigers and the Palestine Liberation Organization; a Bolivian professor of Latin-American history who had been offered a position at the University of Nebraska; a Basque historian; a former Sandinista minister of health; and nine thousand five hundred Burmese refugees.

In these official follies there is an apparent mixture of deliberate ideological exclusion and blind bureaucratic stupidity. Among refugees, the government has kept out anti-Castro Cubans, Vietnamese and Laotian Montagnards, Liberians, Somalis, and Colombian peasants, all of them barred for voluntary or coerced support of armed groups, all of them desperate for asylum in this country. In the aftermath of September 11th, the United States drastically reduced the number of people admitted as political refugees. In 1992, there were more than 130,000; this year, of 60,000 slots, only 41,500 have been filled. Most of these cases of exclusion are so unjust that an unusual coalition of congressional liberals and conservatives is advocating a change to the Patriot Act.

Getting a visa has, inevitably, become harder since 2001. Consular offices have to vet every applicant with a battery of intrusive questions, and if an applicant’s name is Ahmed Abdullah there is a chance that it will light up the name-check system and force his application into a congressionally mandated clearance process that can last months, involving not just the State Department but also the Department of Homeland Security. Because the government’s explanations are so minimal, the ensuing delay seems insulting as well as inconvenient, and by the time the visa is finally granted the applicant’s ardor to rush into the embrace of freedom may well have cooled. Iranians, whom we should be welcoming as freely as possible, suffer particularly arduous waits.

The larger problem is that terrorism has created an atmosphere in which no official wants to be the one who gives a visa to an Al Qaeda operative, while there is no professional price for barring a professor with unpopular ideas or for making a graduate student miss a semester of school. (The number of foreign students admitted annually has declined in the past five years, though the State Department is trying to ease their visa process.) Living in the United States is a better advertisement for America than most of its foreign policies, but it is an increasingly difficult experience for foreigners to have.

The United States should grant Tariq Ramadan a visa, not because he has an inalienable right to one but in the interest of the national good. The continuing effort to keep him out is a strategic mistake, and it shows a depressingly familiar failure on the part of the Administration to grasp the nature of the conflict with Islamist radicalism. It is a struggle of ideas, played out around the world, and a figure like Ramadan, who can appeal to young Muslims on the basis of both group identity and tolerance, is a valuable interlocutor. Allowing him to assume his position at Notre Dame as Luce Professor of Religion, Conflict, and Peacebuilding would not necessarily improve Muslim-Western understanding (interfaith dialogue is overrated, as the Pope recently demonstrated). But it would reduce the “habits of hypocrisy and meanness” that Jefferson identified as the result of legislating against thought. Barring Ramadan makes the country that claims to represent the side of freedom in this struggle appear defensive, timorous, and closed.