It has been left to the right-wing press to take more than passing notice of the arrival of Sinn Fein MPs at offices in the House of Commons. And the Daily Mail and Daily Telegraph headlines - "Sickening", "Adams swaggers into Westminster", "IRA at heart of democracy", "Day of shame" and the like - can be dismissed, with some justice, as infantile attempts to stoke the prejudices of Middle England. Even so, it is the left that should be thinking hard about its attitudes towards Sinn Fein and towards the Northern Ireland peace process as a whole. Such thinking is all the more important when we supposedly face new terrorist threats, from people who are more ruthless and less open to conventional negotiation than the IRA.

On the face of it, Northern Ireland is a triumph for new Labour: the Protestant majority has been persuaded to share power with the nationalist minority, while hundreds of IRA prisoners have been released and fugitives offered amnesties; in return, the IRA has agreed, for the foreseeable future, to renounce violence and to accept that Ulster will remain in the United Kingdom as long as the majority wishes it. Beneath the surface, the reality is cruder and less comforting. The IRA has renounced bombing and it has renounced attacks on politicians, civil servants, the City of London and British army personnel. It has not renounced its control, enforced by violence, over streets in Belfast and Londonderry. Nor have any other terrorist organisations. The winners include almost everybody on mainland Britain, British business, the agents of the British state and (given that the Troubles affected them, if at all, only through security restrictions and city-centre bombings) the Northern Ireland middle classes. The losers are the Northern Ireland urban working classes, who are still subject to the summary and brutal justice of the paramilitaries. The rocket launchers may have been put beyond use. The crude pipe-bombs, the nails, the baseball bats, the guns used for kneecappings have not. Indeed, the casualties from paramilitary shootings are rising; in all, nearly 100 people have been killed since 1998 and there has been only one murder conviction.

To make this point is not to take sides. IRA discipline over the Catholic areas of Belfast and Londonderry is now so strong - with nearly all Protestants cleansed and dissenters mostly exiled - that there is little need for the most extreme forms of violence. In any case, republicans feel that they have all but won the war. Rather, it is the loyalist groups, such as the Ulster Defence Association and the Ulster Volunteer Force, pumped up by the belief that both the British government and their own community leaders have sold them out, who are most guilty of outrages. The most publicised incidents involve Catholics still living or working in loyalist areas. But many of the paramilitaries' attacks are on members of their own community, particularly alleged child abusers, teenage tearaways and drug dealers (which means - given that the paramilitaries themselves deal in drugs - freelance drug dealers). For some of these people, we may have no great sympathy; but they are as entitled to due legal process as any other citizens of the United Kingdom.

The British government has joined the Americans in a "war" on terrorism, a war that has involved thousands of civilian deaths in Afghanistan and the widespread suspension of human rights. Yet in Northern Ireland, it treats daily with some terrorists and allows others the run of the streets. They may be terrorists who have at least partially changed their ways; and they may have killed in dozens, not thousands. But they are terrorists all the same - not, as some on the left imagine, freedom fighters or emerald socialists.

That Sinn Fein MPs have been admitted to Westminster is no more than a symbol; and the British right - like the Irish themselves - gets overexcited about symbols. If anything, it is Gerry Adams and Martin McGuinness who look foolish, proudly raising their flag in the poky little offices of a parliament whose jurisdiction they don't recognise and trying to explain their mysterious policy of "active abstentionism". (One is reminded of the MP who, during a vote against the Callaghan government, crossed the Irish Sea to "abstain in person".)

But the government, in its anxiety to sustain the peace process, sometimes looks too cosily engaged with Mr Adams and Mr McGuinness. At astonishing expense, it has mounted the Saville inquiry into Bloody Sunday, which took place 30 years ago, for no apparent purpose other than to indulge the Irish republican affection for dwelling on past wrongs.

It has turned Sinn Fein from a marginal force into the largest nationalist party in Ulster. The message is that terrorism pays; and it is one that is being heeded by young Protestants who flock to the banners of the loyalist paramilitaries. We must hope that it is not heeded by those on mainland Britain - Muslims and others -who may think that they, too, have grievances.

Turn and turn about

Search "U-turn" on the Guardian's website and you will find 327 references in the past year. Search "Third Way" and you will find 222. This seems an apt commentary on new Labour's sense of direction. Schools are told to avoid expelling disruptive pupils at all costs; then they are told to get rid of them at all costs. Jury trials were out; now they are in. The use of private companies to run hospitals was decisively ruled out two years ago; now, equally decisively, it is ruled in. U-turns on the London Tube and on Lords reform are eagerly awaited. A U-turn on Europe is impossible only because nobody has detected ministers travelling in any particular direction. Do not mock. U-turns may be a sign of a listening government. Or they may signify poor visibility on the Third Way (whose advocates often seem to argue that fogginess is a virtue). Or perhaps it is a ruse by Alastair Campbell to ensure that, by the next election, every voter will agree with at least one thing that new Labour has done.