CULTURE SHOCK:A SCAN OF Wednesday morning's newspapers revealed three things. First, a Ryanair ad in the British papers urging people to fly to Dublin. It featured some books, a statue of James Joyce and the great Long Room library at Trinity College.

The text crammed in all the cliches of literary Dublin: “The Irish have a unique way with words . . . literary giants old and new . . . James Joyce . . . Bloomsday . . . Roddy Doyle . . . Joyce and Behan raised pub-going to an art form, while O’Brien and Heaney all immortalised the Irish boozer . . .”

Second, news of the OECD survey on the literacy levels of 15-year-olds. Ireland’s place in the league table has dropped precipitously since 2000. Over the course of the boom years our ranking fell from fifth in the developed world to 17th – a magnificent legacy of unprecedented prosperity. Almost a quarter of Irish 15-year-olds do not reach the level of literacy required to function effectively in contemporary society.

Third, although you had to look hard in the detail of the Budget measures to find it, all the programmes that might address this problem – adult-literacy, community-education, stay-at-school and Youthreach programmes – are being cut by 5 per cent.

Illiteracy is the dark secret of Irish culture. It is to culture what housing was to society during the property bubble. Just as the number of homeless people doubled during a period of frenzied construction, so functional illiteracy has increased during a period that saw a massive expansion in higher education. And just as no one wanted to talk about homelessness in the midst of a property bubble, few want to talk about illiteracy when “literary giants” are so much a part of our national brand.

One of the phenomena that defined the Celtic Tiger was the adoption of literary greatness as an official truth. Bertie Ahern turned up at Dublin Airport in 2002 to greet Síle de Valera as she arrived from Paris with a cache of James Joyce manuscripts, as if she were a modern-day Moses bringing the word of God from on high. Writers replaced saints and martyrs as the only people whose names could be given to spanking new bridges. The Irish “way with words” became an article of faith, a touchstone of cultural identity.

This was all very well, up to a point. But it has served to mask an unpalatable reality: that Ireland is just as outstanding for its illiteracy as for its literary genius. All through this period about a quarter of Irish adults remained incapable of reading and writing well enough to be able fully to participate in society. This compares with 3 per cent in Sweden and 5 per cent in Germany.

Targets of reducing illiteracy in disadvantaged schools from 30 per cent to 15 per cent have not been met. The Government’s own stated target is to reduce the proportion of the population with restricted literacy to 15 per cent by 2016, an appalling target that will not be met. Even if it were met, we would still mark the centenary of the declaration of a republic with more than 450,000 people unable to read and write properly.

Literacy is overwhelmingly an issue of social exclusion and disadvantage: children from low-income families are already a year and a half behind their middle-class peers in language skills when they start school. But there is evidence that literacy problems are no longer confined to the poor. Teachers at third-level institutions increasingly report alarming levels of inadequate literacy among students.

This week’s OECD figures create the possibility that we may yet pass the most depressing cultural milestone since the rapid decline of the Irish language. It is not alarmist to suggest that we may, for the first time, be creating a generation that is less literate than the previous one.

It is important not to be too apocalyptic about this. Some of the decline in the literacy of 15-year-olds is a result of the influx in the boom years of children whose first language is not English. On the other hand, support for these children is being drastically curtailed: 1,200 teachers of English as an additional language are to be cut from the system.

In such circumstances, there is no reason to expect a radical improvement in the figures over the coming years. Besides, literacy is not a static concept. The number of skills required to function well in a society is increasing over time.

If we end up with a generation that is less functionally literate than the last one a tide of cultural progress will be reversed. Since the mid 19th century Ireland, along with every other developed society, has operated on the assumption that illiteracy would gradually disappear. In 1841, 47 per cent of those over five in Ireland could read. By 1911, the proportion was 88 per cent. In 1926, when compulsory school attendance was introduced, it was taken for granted that functional literacy would be universal within a generation.

There has been much loose talk, ever since Marshall McLuhan used the term in the early 1960s, of a “post-literate” society, one in which multimedia technologies make old-fashioned reading and writing redundant. It is, of course, nonsense. The written word is more abundant than ever. Literacy has taken on new forms (tweeting, texting, e-mailing), but the old ones have become no less relevant. The cost of exclusion from literacy has risen exponentially: there is ever more to be excluded from.

There is a reason why the 19th-century American slave states had specific laws making it a crime to teach a black person to read and why so many slaves risked their lives to become literate. There is a reason why religious fanatics kill teachers and try to keep girls from going to school. And there is a reason why our society sells its “unique way with words” while cutting literacy programmes.

Literacy is a form of power and illiteracy a form of powerlessness. The masters have always known this. The citizens should remember it too.