How long will it be before European liberalism cracks? The aftermath of a terrorist massacre is the worst time to make predictions. The extremity of the outrage pushes policy-makers and citizens to play with equally outraged responses.

It is worth steadying yourself with the thought that until Friday night, Europe’s response to terrorism has not been extreme. Despite gruesome predictions to the contrary, European democracies have not turned themselves into police states. There have been no backlashes or pogroms against Muslims. EU countries, including Britain, have remained free and good societies overall; nations we can be proud of in our necessarily grudging way, for all the faults and abuses we must tackle.

People running from real terror know our true state better than we do. They flee to Europe, not from Europe.

Callous though it may sound today to say it, the modest response to terrorism is the consequence of the modesty of the violence. Since al-Qaida’s assault on the World Trade Center and the Pentagon in 2001, the most striking feature of Islamist terrorism in Europe is how little of it there has been. You can give credit to police forces and intelligence agencies for arresting suspects before they strike. You can repeat the essential point that we are up against Islamism, not Islam, and most Muslims want nothing to do with totalitarian religion. Whatever the reason, the practical consequence remains that no one in power has felt the need to move towards anything resembling martial law.

Europe has “just” endured the attacks on Madrid and the 7/7 assault on London, and the actual and attempted murders of Jews, satirists, freethinkers in Paris, Brussels, Copenhagen and Marseille. Beyond that, there have been “lone wolf” killers of the type who did for poor Lee Rigby.

I am not pretending that Europe has stayed the same. After Islamists sanctioned the murder of cartoonists who mocked Muhammad, a cowardly self-censorship spread across the arts and journalism, which was all the more cowardly for being unacknowledged. But it remains true that radical Islam has not forced a radical break with the past. If you could travel in a time machine, you would see the continuities between our world and the Britain or France or Denmark of 20 years ago hugely outweigh the differences.

I do not mean to minimise Islamist crimes when I say that Europe has been lucky. From Nigeria to Afghanistan, a clerical fascist doctrine that mandates mass murder and self-murder has pushed whole regions into civil war. Yet divinely sanctioned violence has failed to engulf our continent. Suspects are still innocent until proved guilty beyond reasonable doubt. The European convention on human rights remains in force. Terrorism is still subject to the rule of law, not martial law. In spite of all the provocations, we are what we once were.

The co-ordinated Parisian attacks feel as if they are about to change Europe, and change it for the worse. The horrible suffering of people, who just wanted a meal with friends and family, to watch a match or go to a concert, moves the heart. The calculation behind attacks jolts the mind. These killers were not “lone wolves” but “soldiers”, if I may use the term without giving them an unwarranted honour, committing a well-planned and demonically executed crime against humanity.

President Hollande has already abandoned the language of civilian life. He described the atrocities as an act of “war” by Islamic State, rather than a civil crime, and declared a state of emergency. He also threatened to close the republic’s borders. And so he joined a trend.

The borders are closing all over Europe now. The British, with the Channel between the continent and us, do not realise how shocking it would once have been to see fences going up between Slovenia and Hungary, or the Swedes, of all open, tolerant people, putting checks on the bridge between Copenhagen and Malmö. The European Union is meant to be open. Its leaders’ proud boast was that they had dispensed with the nationalist manias that brought so much destruction in the 20th century. Yet even before the Parisian attacks, Europe found the refugee crisis too great for it to bear.

Respectable Europeans may damn the nationalist parties that have risen up against mass immigration as “far right”. They may say that the popular fear that there are terrorists among the refugees fleeing Assad and Isis is absurd. But their criticisms have only infuriated their own citizens. People want physical security as much as they want economic security. Liberals, who denounce anyone who says as much as “neo-fascists” or “racists”, will insult the very compatriots they need to persuade and guarantee their own defeat.

To preserve human rights and prevent a wave of authoritarian governments taking power, you have to accept that some security concerns are real, not a plot by an evil group of conspirators to create a “moral panic”. You must also understand that migration and radical Islamism are changing Europe now, and that if you want a say in the direction your country is going you must first earn the right to be heard by facing that change honestly.

How far Europe will change is an open question. As ever, the future depends on the grim calculus of body counts and attack statistics. After 9/11, commentators predicted that our hedonistic world was over. Irony collapsed with the World Trade Center, they said. Postmodern giggling and smirking were over. In future, we would be serious and sombre people, who looked back on the naive 1990s as a holiday from history.

Nothing of the sort happened, because the predicted wave of violence never came. We remained free to giggle and for that we should be grateful.

Maybe we will be lucky again. Maybe the Parisian attacks will be a rarity, a shocking crime that disrupts our lives but does not fundamentally change them. Perhaps the migrants will be absorbed and the populist parties disappear. Perhaps all those French (and British) citizens who have gone to murder, rape and enslave for Isis will not return to inflict their godly terror on us or inspire online imitators to commit crimes of their own. In 20 years, our children may well be able to look back and say with relief that the continuities with the past outweigh the differences once again.

Perhaps, in short, we will be lucky. But I have to say that looking at the pictures from Paris today it feels as if our luck has run out.

