Many of the worst crimes in history were carried out for political motives by people who felt fully justified in perpetrating them. Their politically motivated offences were still crimes, of course, and could not just be forgotten about. This is a point that entirely escapes Sinn Féin.
A republican ballad recalls how Kevin Barry, a young IRA man hanged for killing a British soldier in 1920, walked to the gallows with his head held high, saying he wished to be shot like a soldier and not hanged like a dog. The song eulogises his political motivation, his clear conscience and his calmness facing death.
The problem is that exactly the same could be said of Saddam Hussein, the Iraqi dictator who showed dignity and courage before his executioners. It is also true of Adolf Eichmann, the SS leader who coined the term "final solution" for the Holocaust, or Nicolae Ceausescu, the Romanian dictator who maintained that history would absolve him.
All three men, generally regarded as monsters, walked to their deaths with their heads held as high as Barry's. Like him, they asked to be shot like soldiers rather than hanged like dogs. They even showed great fortitude in their last minutes.
Hannah Arendt, a Jewish writer who chronicled Eichmann's trial in Jerusalem, concluded that the Nazi was the type of person who "commits his crimes under circumstances that make it well nigh impossible for him to know that he is doing wrong". Perhaps this is the true definition of a political offender.
It would be facile to say that Barry, a boy of 18, was in the same league as these mass murderers. Neither is the IRA to be equated with the SS on the scale of evil.
The fact remains, however, that Eichmann, Saddam and Ceausescu were all political criminals. Their clean consciences and their courage in the face of death does not excuse their deeds.
We will not forget their crimes, nor refuse to mention them for fear of causing offence, any more than we will forget the crimes of the modern IRA. The fact that a person feels good about what he has done does not wipe out the consequences of the action.
It is quite sensible to argue that, since they are unlikely to reoffend now that the terrorist campaigns are over, former paramilitary prisoners in Northern Ireland should be given a break when seeking employment. Most signed an agreement to abide by the ceasefires when released and I believe they should be given the chance to integrate into society, and should not be pushed to the margins by being discriminated against in employment.
It's quite another thing for Martina Anderson to propose that criminal records earned by republican and loyalists during the Troubles should be expunged. She is herself a former bomber captured in 1985 in a flat in Glasgow from where a wave of attacks across Britain was being plotted. She clearly feels comfortable in her own mind about what she has done, and more often talks about her harsh treatment in prison than the mayhem she plotted. One of those captured with her, Patrick Magee, was convicted of murdering members of the Tory party in the Grand Hotel.
The Brighton bombing was undeniably a politically motivated act.
"We had a political situation that produced political prisoners," Anderson has argued. The underlying assumption is that if an assault or robbery is carried out with a political motive, it is less reprehensible than if carried out for personal reasons.
Last year Anderson visited the Scottish parliament as the guest of Margot McDonald, an independent MSP. It was recently put to her that, during the visit, she had said that Tory MPs were legitimate targets. She declined to comment, telling the questioner, Gregory Campbell of the DUP, not to dwell on the past.
Unfortunately for her, this is not how the world sees things.
Again and again the republican movement's view of its actions collides sharply with reality.
In the late 1970s and early 1980s, there were repeated attempts to get international courts to give IRA convicts prisoner-of-war or political status. All were unsuccessful. The grading of offences by motivation was something that had no validity outside republican ideology.
For Anderson, political motivation means that, here and now, IRA actions should not be dwelt on except at republican commemorations when ex-prisoners are congratulated and the dead remembered. At best the political motivation, now that the campaign is over, becomes a springboard for political action of a more conventional type.
"Let us take on this task readily, with determination and with container-loads of energy, following the example of the people down the years who gave their lives in pursuance of this struggle," Anderson said at the Edentubber commemoration for the four IRA members and civilian whose lives were wasted when a bomb exploded prematurely in Co Louth in 1958.
This sort of thinking may be useful as a psychological device to deal with her violent past, years in jail and the death of her friends.
Otherwise, she might suffer the full mental anguish that would normally be associated with such memories. But as a line of argument it won't be accepted by anyone who did not support the IRA campaign. She is speaking a different language from most of the population.
Sinn Féin operates a seemingly unconscious double standard in which the wrongdoing of others is to be remembered and probed, but IRA activity, although it caused pain, sits outside the criminal justice system and truth-recovery process. Anderson, now a member of the policing board, speaks of instances of politically motivated collusion between the security forces and paramilitaries as "crimes against humanity".
Yet IRA actions were never crimes against humanity, because they were inspired by the same sort of political motives she attributes to the police.
The point featured in a recent exchange between Martin McGuinness and Stephen Nolan of the BBC, who has a gift for bluntness.
Nolan asked McGuinness if he had killed anybody. McGuinness hedged and talked about being an IRA leader at a time when people suffered.
"I'm wondering if I am looking at a killer," Nolan persisted. "You can wonder all you like," replied McGuinness.
Asked if, now that he supported law and order, McGuinness would like people to report anything he had done wrong, he replied: "I'm not a criminal. I was never a criminal . . . I'm not asking or advocating that republicans and nationalists should give information on the IRA over the IRA campaign. I can't do that."
This attempt to close the book on the IRA campaign because of its political character, while calling for public inquiries into other acts of violence that sprang from the political conflict, won't wash.
It leaves Sinn Féin looking like hypocrites, having no answers to the hard questions.