All the countries the euro crisis is ravaging can recall a time of dictatorial rule and revolutionary violence. Franco's fascistic regime clung on until 1975, late in the day even by the lax standards of the 20th century. Portugal's 1974 revolution against the Salazar dictatorship was a glorious moment of civil disobedience, but the carnage the revolution accelerated in the old Portuguese colonies of Mozambique, Angola and East Timor continued for decades. Assassination attempts and naval mutinies preceded Greece's revolution against the military junta in 1974 and terrorist groups carried on operating in Greece into the 21st century, as they did in Spain.

Europe, that soft, safe continent of moderate politicians, pacific generals, meticulous bureaucrats, liberal judges and protected workers, is a recent invention. One should not expect it to contain its old demons after the collapse of its hopes.

The first example of the "new politics" emerging from the wreckage of the eurozone is the campaign for the Irish presidency by Martin McGuinness, the butcher's boy who became head of the IRA's northern command. Ireland wasn't a dictatorship in the 1970s, although the gerrymandered Protestant statelet in the north and the Catholic conservative republic in the south were not democratic models anyone else wanted to follow. The violence in Ireland was worse than anything southern Europe saw, however. Between 1968 and the signing of the Good Friday Agreement in 1998, more than 3,600 were killed, around 2,000 of them by McGuinness's IRA.

To understand the effrontery of his candidacy, imagine that Britain was a republic – as we ought to be – and that Tony Blair was considering a bid to be head of state and supreme commander of the defence forces. A brief glance at the rolling news channels would tell him that he was bound to lose. The records of the fallen Gaddafi regime suggest that his administration sent suspects to Libya, who were then tortured. No man should be able to run for office with allegations like that hanging over him.

It is not a mere suggestion but an incontrovertible fact that Gaddafi sent the IRA weapons, which it used to slaughter the peoples of Ireland and Britain. Yet the early polls say that far from viewing McGuinness as the candidate from the psychopathic edge of the lunatic fringe, Irish voters are taking him seriously. A scandal about his views on underage sex has stymied the chances of the best of his rivals, David Norris, who did more for Ireland than the IRA ever managed when he overturned the anti-homosexuality laws. Whatever virtues the rest possess, the failure of the economic system has discredited them, as it has discredited democratic politicians across the west.

If you allow amnesia to numb the brain, McGuinness can seem untainted in comparison. He says he will refuse to take the ¤250,000 salary for the job and manage on the average wage. It's a showy gesture, but a clever one to make in a country trapped in self-defeating austerity, whose government has told its citizens they must take on the private debts of its ruined banks. One should no more go to men who once bombed businesses for an economic policy than seek the advice of the Taliban on the emancipation of women, but when the untutored and forgetful listen to Sinn Féin they hear plausible critiques of the European Union's unbearable demands for debt repayment.

Jim Cusack of the Sunday Independent and a few other Dublin reporters are doing what journalists are meant to do and spoiling the party with awkward questions. McGuinness says he never killed anyone with gun or bomb. All right, they say, you may not have pulled the trigger but how many "spectaculars" did you organise? Whose deaths did you order? Which families are still grieving because of your commands?

In particular, they ask about what happened in October 1990 when the IRA decided that a Catholic man called Patsy Gillespie was a "collaborator" because he found the money to feed his wife and children by working in a British army canteen. The IRA foreshadowed Islamist suicide bombers when it forced him to drive a van bomb into an army checkpoint. Meanwhile, younger readers may need to be told that ITV was once a public service broadcaster. In 1993, its much missed investigative journalism slot – The Cook Report – broadcast the mother of Frank Hegarty, who alleged that McGuinness persuaded her to lure her son back to Derry, where the IRA kidnapped and murdered him for being an "informer". The poor woman went to her grave blaming herself for her son's death.

Too many Dublin journalists don't demand answers but repeat the conventional wisdom that McGuinness and Gerry Adams deserve praise for becoming men of peace. Praise would indeed be due if the IRA's leaders faced the past truthfully.

Their war was futile because the power sharing and cross-border institutions the IRA settled for in 1998 had been on offer since 1974. All the people the IRA, Protestant paramilitaries and the British army killed in the intervening decades died for nothing. Sometimes, it seems as if the only person stating the obvious is the Guardian and Observer's Ireland correspondent Henry McDonald, but his point needs repeating: the ranks of the IRA were filled with the world's slowest-learning murderers. It took them a generation to realise their dream of uniting Ireland by violence was a malign fantasy.

McGuinness and Adams cannot admit it, for how can they tell the imprisoned men and the widowed women that the cause for which they suffered was a waste of time? They keep the idea of violent republicanism alive by pretending that it was a justifiable reaction to British oppression or a continuation of the struggle for Catholic equality by other means.

In other words, Ireland may soon be welcoming a president who cannot be honest with the electorate, cannot be honest with supporters and cannot be honest with himself. He will use the presidency as a megaphone to boom out the myths he has to believe. As always, the surprise is not that the politician lies, but that so many in Ireland and beyond want to be lied to.

There is a temptation to believe that change always brings some good. "You never want a serious crisis to go to waste," said Obama's adviser Rahm Emanuel after the crash, because it offers new opportunities. As the remnants of the IRA rise in Ireland and nationalist anti-immigrant parties rise across Europe, we may be about to learn that recessions rarely bring anything but change for the worse.

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• The following correction was published on 2 October 2011:

"McGuinness's candidacy is an affront to decency" (Comment) referred to "Portugal's 1974 revolution against the Salazar dictatorship". António de Oliveira Salazar served as prime minister (and briefly as president) from 1932 to 1968 and died in 1970. It was his successor, Marcelo Caetano, who was deposed in 1974.