LARGELY because of the incompleteness of official data, few confident statements can be made about the precise nature and extent of crime. However, international opinion suggests the following propositions are probably true (I) there is no such thing as a crime free society (2) the bulk of serious crime is committed by young males under 25, and (3) the majority of offenders cease their criminal activities by 25 and only a tiny minority continue beyond 35.

Although these seem trivial facts, and probably for that reason tend to be ignored in popular discussions of crime, they actually hold the key to a balanced understanding of the problem.

Since there is no known example of a society, either ancient or modern, completely free of crime, it follows that the crucial question is whether a given society has more or less crime than you would expect in societies of its type. The so called crime problem is essentially a quantitative issue that can only be meaningfully measured in comparative terms, by examining the objective evidence from other countries and comparing it with the objective evidence at home.

When this is done for Ireland, it is quite plain the rate of serious crime in Ireland (i.e. the number of crimes per 100,000 of population) is substantially lower than that of any of our European neighbours and spectacularly lower than in the United States.

For example, no one would claim that Scotland is in the grip of Hobbesian disorder, yet the murder rate in that country is approximately double the Irish rate.

Indeed, there are proportionately more homicides in Scotland than there are serious woundings in Ireland. Similarly, the serious crime rate in the Netherlands, a stable, peaceful country about the size of Munster, is about three times greater, and in England and Wales four times greater, than in Ireland.

Moreover, the relatively low Irish rate is not a new phenomenon. Although domestic and rates have increased substantially over the past 25 years, the difference between them has steadily improved in Ireland's favour over the last 20 years.

FROM a criminological viewpoint, this means that the question in Ireland is not why there is so much crime, but why there is, relatively speaking, so little of it. Doubtless this will be dismissed as boffin speak by many old enough to remember the country 30 years or so ago, when there was undoubtedly Jess crime than there is today.

Yet it is worth remembering that a principal reason for the relatively low rate of a generation ago was that the size of the crime prone age group effectively those under 25 was significantly depressed by large scale emigration.

In short, the Irish crime rate of a generation ago was artificially low and so provides a distorted base from which to measure current trends and patterns. Although it is natural to look back (as the editorial writers in this newspaper are fond of doing) when assessing the contemporary figures, the correct scientific posture is the side wards glance.

In my view, a good deal of the confusion in the current debate stems from a failure to appreciate the importance of this distinction. It is difficult to overestimate the significance of the fact that the bulk, of serious crime seems to be committed by young males under 25. Perhaps its chief importance is that it points up the dangers of over theorising the causes of crime.

A striking feature of the current discussion is that virtually everyone, liberals and conservatives alike, seems determined to believe that social conditions lie at the root of the problem. I have always been sceptical of this view, if only because it fails to account for the phenomenon of spontaneous recovery by and large, criminals tend to give up crime shortly after their 25th birthdays.

If social deprivation and alienation really do cause crime, why should they cease to exert their influence on the over 25s? And why is it that they appear to have virtually no influence on females (who are massively under represented in the criminal statistics)? There are no conclusive answers to these questions and this alone should make us wary of those who, often without any specialist knowledge, recommend expensive community based solutions to the crime problem.

Improving the lot of disadvantaged communities is undoubtedly a good thing in itself and should be pursued for that reason, but there is no scientific reason for supposing it will significantly affect the crime rate.

IF fluctuations in the rate of serious crime against the person are largely a function of the relative size of the crime prone age group, the beginning of wisdom is to accept that the present relatively low levels of this kind of crime are likely to continue until the youth bulge gradually works its way through the population.

Because the crime prone age`group appears to be shrinking, where fluctuations do occur, the movement is likely to be downwards rather than upwards.

In this sense, crime against the person is a bit like road accidents or serious illness we can and should take precautions against it and worry if it exceeds statistically expected levels. But it is vain to try to eliminate (or even significantly reduce) it as long as the demo graphic factor which most accurately predicts it remains an integral feature of the social landscape.

This argument is also relevant to calls for changes in the arrangements governing pre trial detention. I am one of those who believes the existing bail laws are too lenient. In my opinion, it is an affront to common sense that someone who is likely (as measured by past experience of the individual in question) to commit further offences if released should nevertheless be given bail because of the requirements of retributive justice.

However, I do not believe tightening the bail laws will significantly reduce the level of crime.

Apart from the fact that it is unlikely more than 10 per cent of serious crime is committed by persons on bail, there is the added difficulty that, since most prison sentences are short and ineffective, the likely effect of denying bail would merely be to postpone the moment of re offending. It should also be borne in mind that legal systems with relatively stringent bail arrangements (most European systems, as it happens) also have relatively high crime rates.

The argument for more prisons spaces is also flawed. The crisis in "the prison system arises because, like the United Kingdom but unlike many of our European neighbours, we have not faced up to the fact that penal measures are more or less interchangeable from the point off view of their effectiveness. They are all more or less equally effective (or equally ineffective, if you prefer) as measured by the reconviction rates of those exposed to them.

The logic of this is that short prison sentences are, by and large, an expensive waste and could and should be avoided without any loss in the deterrent efficacy of the criminal justice system as a whole.

The extra space generated by a policy of evacuation of this sort would, in my opinion, be more than adequate to cater for serious offenders who, for reasons of social protection, need to be incarcerated for long periods.

But I concede this is a difficult trick to turn, that there are difficult questions of definition involved in bringing it off, and vested interests within the criminal justice system (not to mention public opinion) may well ensure that it is not even attempted.