What is education for? Faced with that test question, most people would perhaps suggest: to ensure that every young person acquires a rounded set of skills for working life and an ability to get along with others in the adult world.
It is very unlikely that they would answer: to ensure that successive generations of children are socialised into the ethos of one religious denomination rather than another – regardless of such mature choices as they might themselves make – and are sorted at age 11 into different schools for different social classes.
Yet it is the second set of imperatives which drives the education system in Northern Ireland, captured historically by the particular interests of the churches and the middle class, at the expense of the wider public good.
And 'expense' is the word. When Deloitte produced a report shortly after devolution was renewed, suggesting sectarian division in Northern Ireland cost up to £1.5bn a year, the fragmented education system, with its tens of thousands of spare places, loomed large.
Needless to say, the two political parties benefiting most from the maintenance of that division – the DUP and Sinn Fein – sought to suppress the report.
But the bigger cost is human. This week, the closure was reported of the last Catholic school on the Waterside in Londonderry. What really then becomes the point of a 'Peace Bridge' across the Foyle, if all it does is symbolise how children on either side of it are growing up as if on different planets?
Great work is done with young people in Derry by the Nerve Centre. But its staff recognise how much youngsters in the city are induced into a sectarian groupthink, corralled into a communal sub-culture defined by the murals on the walls.
We know from social psychological research that children as young as three in Northern Ireland start to recognise sectarian symbolism. Conversely, we know from attitudinal research on those who have attended integrated schools that the experience has an enduring effect in fostering tolerance in adult life.
We know, too, from international comparisons of pupil competences that, while Northern Ireland's primary teachers do a job of which they can be proud, the region falls behind markedly at secondary level, when teachers have to work with a majority of demotivated children told they were failures at age 11.
Inevitably, there is a business cost, too. Firms don't thrive with demotivated workforces. Also this week, the Integrated Education Fund published survey evidence showing that employers recognised the negative impact on staff of having been schooled only with their co-religionists.
Successful enterprises today depend on teamwork and the ability of staff to find solutions to problems collectively. Gone are the days when every car-buyer could have any colour they liked as long as it was black and so frontline staff have to be able to use their discretion to provide customised solutions and to communicate with customers and colleagues so to do.
And in today's globalised environment, it is increasingly unlikely that those customers and colleagues will be "people like us". They may well be of different nationalities, or different ethnicities; indeed, they may well be on the other side of the world. Individuals who instinctively mistrust anyone outside their religious in-group will fare badly in such an environment.
Moreover, a knowledge economy with the internet at its heart makes rote-learning redundant. What young people need to learn more than anything at school is how to learn by themselves as they go through life – beginning with knowing how to ask the right questions. This is not a world for those schooled to cite verses from a supposed holy book.
Northern Ireland's education system needs to be fundamentally restructured, removing the churches and the middle class from control, so that – as in the best performer in Europe, Finland – every local school is a good school to which everyone locally goes.
The needs of every young person, accorded equal citizenship with his, or her, peers, should thus be front-and-centre. Like the wonderful pre-school system in Reggio-Emilia in Italy, where children don't begin formal schooling until age seven, it should be about guiding the child in a supportive way through the formative years of a life of self-inquiry.
In Northern Ireland, this seems a revolutionary proposition. Yet this only reflects how much of an educational backwater it is.
Elsewhere in Europe, the second answer to the "What is education for?" question would simply be baffling.
It is good that the business community is joining the educationalists and progressive parents who have led the integrated education movement in putting it up to the sectarian politicians: you do not speak for us. It's time they listened. Ultimately, what education is for is very simple.
It should not be a communal good for the clerics subtly in control of the state system and explicitly in control of the maintained alternative.
Nor should it be a "club" good for the middle class, ensuring they can work the system to get their progeny into the top Belfast grammars.
It should be a public good for everyone.