Last Friday night, according to the Scottish Prison Service, 8,023 individuals were classified as prisoners in Scotland.

Of these, 7,732 were actually in custody; 399 were female; 414, of both sexes, were young offenders. For a small country, those are big numbers.

At the end of May, the International Centre for Prison Studies reckoned Scotland's prison population to rank 21st in Europe on a per capita basis. Doesn't sound too grim? Discount Turkey and the states of the old Eastern bloc and you find Scotland close to the head of the list of European nations, particularly the western nations, when it comes to locking people up.

At 143 prisoners for every 100,000 citizens, we trail (if that is the word) only England and Wales (149), Guernsey (148) and Gibraltar (146). Unless you are of an especially punitive disposition, this is not a proud record.

Is crime so much worse in Scotland than in France (100 per 100,000), Austria (96), Italy (86), Ireland (82), or Germany (76)? Comparisons with Scandinavian countries are almost laughable when the Norwegian rate is 72 and the Danish rate just 62. Other nations do better still. Why is that, and what can - or should - be done about it?

The debate over automatic early release is raging again. The argument continues over whether women should be locked up, least of all for mostly petty offences. Now ministers mean to consult on whether the presumption against short-term sentences, for men and for women, should be strengthened.

In terms of cost, there is no real argument. In 2012, the average annual cost "per prisoner place" was £32,371. Satisfying the instinct for retribution when lesser offences are at stake is an expensive business.

So does imprisonment deter? International comparisons alone undermine the argument. Reconviction rates have been declining gently in recent years, but at 28.6 per cent (2012/13) with an average of 0.51 reconvictions per offender, the claim that "prison works" is suspect indeed.

Scotland's prison population has been growing for decades. In 1960, fewer than 3,000 were classified as prisoners; in 1990, fewer than 5,000. Claims that governments, of whatever persuasion, have been "soft" do not stack up, even granting demographic changes.

Where lesser offences are concerned, we lock up too many with too little cause at too great a cost and fail to identify the benefits, whether in terms of reconviction or rehabilitation. Meanwhile, too little use is made of community supervision as an alternative to prison. Penal policy is driven by rhetoric, popular misconceptions, and political opportunism.

If Michael Matheson, Justice Secretary, therefore means to "seek views" to explore extending the presumption against short sentences, he has this much on his side: nothing else has worked. Belgium has just done away entirely with sentences of a year or less. The existing presumption against three-month sentences has meanwhile failed, it seems, to wreak havoc.

It therefore falls to those who believe we can go no further to make their case. They might begin by attempting to justify existing prisoner numbers. Is everyone in Europe out of step save Scotland?

That said, much more needs to be done to guarantee the effectiveness of community sentences. Such programmes must be properly funded and supervised. Whether the aim is rehabilitation or retribution, law and order remains the first priority.