Editor's note: David Frum writes a weekly column for CNN.com. A special assistant to President Bush in 2001-02, he is the author of six books, including "Comeback: Conservatism That Can Win Again" and is the editor of FrumForum.
Washington (CNN) -- Firebombed. Cyberattacked. Attacked by a shouting mob.
That's what happened to Lars Vilks in the week ending May 16.
And if you think: "Well thank goodness my week was a lot quieter," think again. The attacks on Vilks were an attack on you too.
Lars Vilks is a Swedish cartoonist. In the summer of 2007, he was invited to submit three drawings to an exhibition sponsored by the town of Tallerud. The exhibition's theme: "the dog in art." Vilks produced three pencil sketches of street dogs with human faces, the face (Vilks said) of the Islamic Prophet Muhammad.
Even if you don't know the rest of the story, you can easily imagine.
In March, police in Ireland arrested seven people on charges of conspiring to murder Vilks. The same day, U.S. law enforcement announced the indictment of an American woman who had attempted to recruit assassins to kill Vilks.
Yet Vilks has refused to be intimidated. On Tuesday of this week, Vilks appeared at the University of Uppsalla to lecture on his art and ideas. Two-hundred-fifty people passed through metal detectors to hear him speak. They never got the chance. Vilks opened his talk with a provocative short video that included an image of two nearly naked Iranian gay men wearing masks of Muhammad. At that cue, about 20 rowdies in the crowd shouted, "Stop the film! Stop the film!"
The rowdies rushed toward the stage. One of them apparently struck Vilks. Police sought to restrain them. After eight or so minutes of chanting, yelling and fist-pumping by the rowdies, the university suspended the performance.
You can watch the incident here in a 10-minute YouTube clip.
The blogger who writes under the pseudonym Allahpundit directs attention toward two aspects of the confrontation that might be overlooked in the excitement: the ineffectiveness of the police and the passivity of a crowd of spectators who outnumber the protesters by at least 10 to 1.
Daily life in Sweden and other European countries is increasingly governed by an unwritten set of rules very different from the country's formal law.
The formal law forbids assault and upholds free speech rights. The actual rules of the game, however, concede that certain assaults and certain violations of free speech rights may proceed with impunity. Police arrested two men for disrupting the Vilks event; both were released without charge.
Impunity invites further attack. In the aftermath of the Uppsalla University incident, Vilks' website was hacked and firebombs were planted in his house. (Two men have been arrested in connection with the firebombing.)
The authorities look the other way in hope of obtaining social peace. This policy does not work, and for two reasons:
First, the policy of impunity emboldens aggressive minorities. Instead of accepting that they must live and let live, these groups get the message they can dominate others by the threat of force.
But second, the policy of impunity backfires. While the authorities want quiet, ornery individuals like Lars Vilks are delighted to bust taboos and foment the very confrontations the authorities wish to avoid.
Vilks is just one of a multiplying band of deliberate provocateurs who have appeared across Europe over the past five years. Their work may not have much artistic merit, but the issue here is not art but courage. And there will always be enough courageous people to complicate badly the lives of uncourageous authorities.
The irony is that these uncourageous authorities would gain much more quiet if they upheld their formal rules. When the rules are clear and enforced, almost everybody will conform to them. Expel one student for disrupting a campus event, and you are unlikely to have to expel a second.
But when the authorities declare a "moral holiday" (to update an old phrase from the U.S. urban riots of the 1960s), otherwise law-abiding people seize the opportunity. They commit acts of intimidation and violence they would never have dared if law-breaking had been met by immediate sanction and certain punishment.
The opinions expressed in this commentary are solely those of David Frum.