Bruce Anderson: If the violence was Catholic, you would try to understand the anger behind it

Their basic problem can be summarised in one fashionable word: narrative. Throughout the world, millions of people who understand none of the complexities of Irish politics believe that they know the narrative. There are oppressed Catholics and oppressing Protestants. The Catholics are southern blacks under segregation, South African blacks under apartheid. The Prods are the Ku Klux Clan and the Afrikaaners.

In sustaining this narrative, Sinn Fein has a further advantage: music. "The Sash My Father Wore" cannot compete with "Kevin Barry". The Devil has the best tunes. Never has homicide been sentimentalised more mellifluously than in the ballads of the Irish republican movement.

Forty years ago, the Catholics of Northern Ireland had grounds for complaint. On the grievance-ometer of the 20th century, they would hardly have registered, but in the United Kingdom, redress should have come earlier. When it did, however, it was thorough. All the legitimate grievances of the Civil Rights movementhad been dealt with before the mid-Seventies.

Yet this had no effect on the narrative. Even while London was righting the wrongs, the Civil Rights movement was changing its nature. Instead of demanding equal treatment within Northern Ireland, it was becoming a popular front to advance the interests of revolutionaries who wanted to destroy Northern Ireland.

As a result of their propaganda successes, there are still those who question Northern Ireland's right to exist, claiming that Ulster's Protestant population are only colonialists. But they have been there for around 350 years; surely an entitlement to permanence.

It is also alleged that the boundary between Ulster and the Irish Republic was merely the creation of a treaty after a conflict. Yet the same is true of almost every international boundary in Europe. If Northern Ireland is illegitimate, so are France, Italy, Germany, Poland and Russia.

But by bringing Ulster's status into question, the Republicans have laid the grounds for other victories. On the left, many of those who accept the existence of Northern Ireland do so grudgingly and resentfully. The assumption is that if the Northern Prods are allowed to retain their dubious statelet, the very least that they can do in return is to apologise to their Catholic neighbours at every opportunity. If any Catholic should ever complain about his treatment, he must be in the right.

The Prods are aware of all this, which is why some of them behaved disgracefully over the weekend. They too have a narrative, and it has the merit of historical accuracy. According to the Ulster Protestant version of history, there are two nations in the island of Ireland. In the early 20th century, when the British government chose to ignore this by proposing to grant self-government to a united Ireland, the smaller nation was entitled to demand its freedom. After all, that was the era of Woodrow Wilson and the rights of small nations.

Above all, the Ulster Prods would draw attention to the past three decades, when they were menaced by a campaign of murder and ethnic cleansing. Seven years ago, in an historic compromise, that campaign should have ended. The murderers were to be released, while some of those who ordered the murders were allowed into government. In exchange, the IRA would disarm and disband; it would cease to function as a paramilitary organisation.

Seven years later, many Protestants feel betrayed. There has been an insignificant degree of disarmament and no disbanding. The IRA is still a paramilitary organisation, enforcing political control over many Catholic urban areas in Northern Ireland, while financing itself by crime.

Not only that: Tony Blair seems determined to bring Sinn Fein back into government as quickly as possible, on almost any terms. A few weeks ago, London, Dublin and Washington were insisting that, before being re-admitted to government, Sinn Fein would have to produce photographs to produce that decommissioning had taken place. Now, that demand has been dropped; Gerry Adams did not like it. To many Protestants, it seems as if, despite the £26m bank robbery and the McCartney murder, Adams is controlling the agenda.

A lot of ordinary Ulster Prods now believe that the British government has lost all interest in moral fundamentals and that its sole concern is to avoid renewed IRA violence. That is why some people have now resorted to violence. Although they should not have done it, one point is worth making. Had the rioters been Catholics, condemnation would have been interspersed with caveats about the need to examine underlying grievances. Why should the same not apply to the Prods?

Their grievances are genuine. They believe that their political rights have come under attack, first by the IRA, and then by successive British governments who continuously disregard their views. They have not only lost confidence in their political leaders, but in the political process itself. Ulster Unionists will tell you that theirs is the only country in Europe where the majority is incapable of using the ballot box to make sure that its views prevail in government.

That is the background to the weekend's riots. Many Protestants have come to feel that it is time to stand up and fight back. This was not only morally wrong; it was tactically absurd. Any Ulster Protestant who thinks that he can win over world opinion by asserting the Orange Order's right to march proves that he knows nothing about the outside world. But no one should be complacent about the fact that despair is leading some otherwise decent people into misjudgement and violence.

The situation in Ulster is dangerous. No wise British government should welcome the alienation of the Protestant majority. Yet, if he chose, Tony Blair could easily prevent the situation from deteriorating further. All he has to do is return to the principles of the Good Friday Agreement, which he negotiated.

Under that Agreement, disarmament was a precondition for entry into government. No organisation that retained its guns would be allowed to function as a political party. This is not only the right solution for Ulster; it is the only solution for any civilised country. Unless and until Tony Blair is prepared to stand by those basic democratic values, things will only get worse.