The attacks in Paris and the ongoing fear of further attacks in Europe by Islamic extremists have resulted in some shifting in Irish attitudes to the migrant crisis in Europe, and in particular to the number of refugees from Syria we have committed to accepting in the months and years ahead.

This was not evident in the speeches made by politicians in the Dail in the aftermath of the Paris attacks or in most of the commentary in the mainstream media here. But on social media, in calls to radio shows and in letters to the papers, some people here have been expressing concern about what is planned.

We are to take in 4,000 refugees, mainly from Syria, with the first of those due to arrive in the coming weeks and months. The government here accepts that, with family reunifications, that number is likely to reach around 20,000 over the next few years. Work is already underway here preparing reception centers for the refugees.

Unlike in the U.S., where more than half of state governors have said they are not prepared to accept any Syrian refugees, at least without major changes in vetting procedures, our official stance here is still to provide an immediate and welcoming haven for those fleeing the conflict in Syria and the conditions in surrounding countries. Arrangements for selecting and vetting those who will be coming here are still far from clear.

At official level we have expressed our sympathy with the victims of the Paris attacks and our solidarity with France. Those expressions of sympathy and support are shared by everyone here. But there are genuine worries about what lies ahead in Europe and even here in Ireland.

Our politicians have repeated that Ireland will play its proportional part in dealing with the influx of migrants into Europe under the plans agreed by the EU in recent months as the migrant crisis worsened. That is where the figure of 4,000 refugees for Ireland comes from: It is our share of the number Europe has agreed to take.

But the fact is that the plans agreed by European leaders -- with some exceptions -- would deal with only a small percentage of the numbers of migrants into Europe which will far exceed a million this year, with a few million more likely to follow in the next few years. Even before the Paris attacks, the inadequate plans for accepting migrants were already in trouble.

Rather than being a well thought out solution, they were a reaction by leaders to the sympathy across Europe and in Ireland for the plight of migrants crossing the Mediterranean and making the difficult journey up through the continent.

That outpouring of sympathy and demands for action peaked after pictures of the body of that tragic little boy washed up on a beach were published around the world. But the reality and the scale of what is happening is now making people think again about what Europe can -- or should -- do.

The huge number of migrants arriving in the last few months has forced even countries like Germany and Sweden to rethink their previous open door policies. Across Europe, and particularly in the countries through which the migrants have been passing, there are differing views on how to handle the situation.

Several countries in southern Europe have built fences and closed their borders. Even the wealthier countries in northern Europe have now reached the conclusion -- pushed by growing public concern -- that there is a limit to the numbers they can accept and have introduced much stricter controls.

There is now some doubt about whether the Shengen area -- the 26 countries in Europe which allow free movement between them for their citizens without passport controls -- can continue to operate. Since the Paris attacks, these concerns have intensified.

At least some of those involved in the attacks had moved between ISIS controlled areas in Syria/Iraq and Europe under the cover of the migrant flow. There is now an emerging consensus in Europe that the number of migrants who can be accepted must be limited, and that much more stringent vetting procedures must be introduced. People are rethinking what it means to have so many migrants coming in.

An equally worrying security threat, however, is not from the recent flow of migrants but from home grown terrorists, as the profiles of those involved in the Paris attacks demonstrates. The attackers were young men (and at least one woman) born in France or Belgium into poor, mainly Muslim areas where there are concentrations of immigrants who have been there for many years.

On the ring road around Paris there are large suburbs of run down apartment blocks where most of those living there have roots in Algeria (a former French colony), Morocco (formerly run by France and Spain) and other parts of north Africa. Some of those involved in the Paris attacks were from Molenbeek, a poor suburb of Brussels with a substantial Muslim population which has been described by Belgian officials as a "breeding ground for jihadists." And there are other cities and towns in France and elsewhere in Europe with large second and third generation immigrant communities concentrated together in poorer areas.

This is a big challenge. Integration in France and elsewhere has been poor even after one or two generations, and there are unemployed, disaffected young men and women from immigrant families who feel excluded and have little loyalty to the country they were born in.

Instead there is deep resentment. The alienation and boredom they feel makes them easy fodder for radicalization. The Paris attackers are examples of this.

Instead of being devout Muslims committed to fighting against the so-called wicked west, they were losers who dabbled in drugs, alcohol and sex, living on welfare and spending much of their time playing video games and drifting around. Joining up to fight on the fringes of Isis may have given them a new sense of self-worth, purpose, even excitement, they had never felt before. That was probably just as important a factor for the Paris group as any understanding they had of the overall aims of ISIS and its desired caliphate.

Of course the majority of immigrants do integrate and become a successful part of their new countries in time, particularly after a generation or two. But many don't and the poverty and exclusion felt in some of these communities in deprived suburbs of Paris, Brussels and other cities is a real problem for Europe.

The promotion of multi-cultural policies in Europe has been seen as the politically correct thing to do for some time. The aim has been to respect the culture of immigrant communities while encouraging them to be part of the new society in which they live.

The reality, however, is that multi-culturalism has often ended up being mono-culturalism, with immigrant communities living together in their own areas and doing little to accept the norms and values of the wider society.

There is nothing new in this, of course. Immigrants have always tended to gather together in particular areas (as the Irish and other nationalities did in parts of New York, for example).

The difference in the U.S., however, is that most immigrants quickly become proud Americans, even while retaining some of their own traditions and cultures. That has happened less in Europe.

One can see it in parts of Britain, for example, with particular districts in London and some Northern cities like Leeds and Bradford having majority immigrant populations where there is not much sense of being British among the youth.

For Ireland, out on the edge of Europe, these issues have so far not posed a problem. Even so, there are parts of the inner city in Dublin and some of the outer suburbs where there are concentrations of immigrant families.

Given the very high level of immigration here during and after the boom -- a rate far higher than immigration into the U.S. in recent years -- we have yet to see what the effects will be on Irish society.

We have adopted the same glorification of multi-culturalism as seen elsewhere in Europe, with political leaders and others encouraging people here to celebrate "the new multi-cultural Ireland" without any objective evidence that such a change is a positive development. This has been enthusiastically supported by the media, to a degree that is almost comical at times.

For example, any TV report on schools will always feature immigrant children prominently in the foreground, no matter where the school is or what proportion of immigrant children it has.

To be fair, in some schools in the areas already mentioned, this is an accurate reflection of the school population.

In these areas well over half of the children in junior classes are from immigrant families, many of whom have little English. There were promises of many extra language support teachers, but since the bust these have remained unfulfilled and schools have been left to cope as best they can. Instead, we are left with gestures like putting immigrant children on the covers of many school textbooks.

We now have a sizable Muslim population here, a small minority of whom are known to have connections with Al Qaeda and other radical organizations and are being monitored by the Gardai. A few dozen are known to have gone from Ireland to fight with Al Qaeda and, more recently, ISIS.

Discussion at official level here of these issues is shrouded in political correctness. But on social media and in other outlets like radio phone-in shows, there is a growing sense of unease at what all this means for the country.

In particular, many people express their anger at the way "the new multi-cultural Ireland" was presented as a fait accompli and turned into a reality without any prior discussion with or approval by voters.

The general view is that Ireland -- for the foreseeable future at any rate -- is unlikely to be a target for extremists of the ISIS type, although the use of Shannon by U.S. military aircraft is seen by some as putting us in danger. A bigger worry is that an extremist from an immigrant background in Ireland might surface as an attacker in France or in Britain, to where we have easy access.

All told, the Paris attacks have prompted many people here to think again in a very pragmatic way about what the migrant crisis and large scale immigration means not just for Europe in general but for Ireland in particular.

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