Two key immigration issues are the actual scale of the current inflow of non-nationals into our State, and whether and to what extent Irish workers may be suffering "displacement" by some lower-paid immigrants.
If we are to avoid the emergence of xenophobic attitudes and tensions, it is important that both of these issues be examined dispassionately.
Until very recently almost the only data published with respect to the scale of immigration were figures for the number of people from new EU member states registering for work here.
In the absence until now of data on the number of immigrants actually remaining at work here, these registration figures which tell us nothing about how many of those registered returned home again after a short stay here, have given a hugely exaggerated picture of the size of our immigrant workforce.
The detailed data published on Thursday by the CSO should reassure the public, who have been confused for some 18 months past by the publication of incomplete data.
For it is now clear that at the end of last year fewer than 62,000 people from the 10 accession states were at work in our State, out of a total of 170,000 who had registered for work here during the preceding 18 months - or who in a small number of cases, were already working here before May 2004.
In other words, well over 100,000 of these workers - almost two-thirds - had been in Ireland only temporarily, and by the end of last year had already returned to their own countries, with whatever income they may have earned while in Ireland.
Of course eastern Europeans are not the only non-nationals working in our State. At the end of last year there were also 41,000 UK nationals, 22,000 workers from the 13 other pre-accession EU states, and 47,000 from other parts of the world, including perhaps 12,000 from the United States.
The other currently controversial issue is what has been described as the "displacement" of Irish workers by lower-paid immigrant workers. It is important that this matter be teased out in some detail.
First of all, it should be made clear that one-half of the increase in our workforce last year consisted of Irish workers - including, most strikingly, more older workers remaining on at work; and many more women entering, or re-entering, the workforce.
Next, it needs to be emphasised that throughout this recent period of higher immigration, unemployment has continued to fall.
In every single quarter since our borders were opened to workers from the accession states our overall unemployment rate has been lower than it had been a year earlier.
In fact, since mid-2004 the overall level of unemployment has, on average, been 5 per cent lower than in the same quarter of the preceding year - and, as the unemployment rate of Irish nationals is almost 30 per cent lower than for non-nationals, the drop in the rate of unemployment of Irish workers must have been greater than 5 per cent.
In two of the 10 non-agricultural sectors of the economy - manufacturing and the catering sector - there has been some replacement of Irish workers by non-nationals, but to describe this as "displacement" of Irish workers could be misleading.
For, given the very healthy employment situation, the 20,000 drop in the number of Irish workers in these two sectors could well reflect a movement of lower-paid Irish industrial workers into better-paid employment - 7,000 of their low-paid jobs being then taken over by non-nationals.
That kind of shift in the pattern of Irish employment change would be clearly beneficial - for it would simultaneously raise the living standards of some Irish workers, whilst at the same time improving the competitiveness of some labour-intensive sectors of manufacturing by reducing their labour costs. To me, at least, "displacement" of Irish workers would arise only where they lost their jobs to lower-paid immigrants and were then left unemployed, or were re-employed at a lower wage than that which they had previously received. I do not regard workers as "displaced" if they move from lower-paid jobs for better-paid work in another sector, and if some of them are then replaced by immigrants.
Whatever may have happened in some individual cases, in an 18-month period during which unemployment of Irish workers was on average down by more than 5 per cent, and when the number of Irish workers actually increased by 65,000, it is hard to believe that there was much actual "displacement". Nevertheless, we must recognise that immigration can have adverse social effects, and it is right that we should guard against such dangers - a process in which the trade unions are exercising a valuable role.
Some unscrupulous employers have sought to undermine employment standards by exploiting immigrants, whilst at the same time cheating the State by evading their tax liabilities. There seems to be considerable evidence that this has been happening on a substantial scale in the construction industry, and while the Revenue Commissioners have said they are now starting to clamp down on such malpractices, it would have been better if they, and the grossly under-staffed labour inspectorate, had moved to tackle this situation before it got out of hand.
Quite apart from that kind of abuse, it would also be possible for large-scale immigration of low-paid workers to undermine generally the earnings of Irish unskilled or semi-skilled workers, and that would be socially undesirable - especially given the high level of income inequality that already exists in our society. Hitherto this kind of effect may have been avoided here because so many of the workers from eastern Europe have been temporary visitors, and because most of those who have remained here are in fact people with useful skills and qualifications, which they have initially been unable to deploy because of an inadequate command of English that has temporarily confined them to unskilled work.
Up to this point at least, the type and volume of immigration that we have been experiencing has clearly been very beneficial for our society, and the Government would be unwise to succumb to pressure to restrict it.
But the Government should also be prepared to resist any exploitative pressure from employers and to take firm action against any abuses of power.