My daughter and her friend recently gleefully posed me a riddle: There are two towns, Liestown, where the inhabitants always lie, and Truthstown, where everyone tells the truth. A man from one of the towns says: "I am from Liestown" - do you believe him?
Sinn Féin's credibility problem is a bit like this. In republican theology, Sinn Féin members who also belong to the IRA are obliged to deny this connection because it involves a criminal offence. Sinn Féin denials of criminality, therefore, literally cannot be believed.
Similarly, persistent demands by Sinn Féin for "proof" of criminality, implying that no charge can be sustained against the republican movement other than on the basis of the accepted legal standard of "beyond reasonable doubt", are an unsustainable invocation of the logic of Truthstown.
Everyone knows the IRA exists, what it does and why, that it has leaders, and that there are strong ties and a high degree of cross-membership between Sinn Féin and the IRA. And everyone knows also that Sinn Féin, to the extent that it is separate from the IRA, not merely respects but venerates the military wing. To suggest that there is something preposterous in the observations being made about such connections is to treat the public as though it was unentitled to employ common sense.
Although continuing exchanges about republican criminality exhibit superficial similarities to a debate, the discussion is taking place in two distinct languages pertaining to irreconcilable perceptions of reality. Politicians such as Michael McDowell believe that, as defenders of the rule of law, they speak to the highest form of public morality.
But republicans, in their own minds, also inhabit the high moral ground. They believe that years of combating injustice under the banner of the Irish nation's struggle for integrity confer on them the right not merely to engage in what Michael McDowell insists on calling "criminality", and to deny such involvement in order to prevent him putting them in jail, but to refuse the idea that the term "criminality" is appropriate at all.
Thus, republicanism is protected by a series of semantic Chinese walls which the logic of the wider world is not just incapable of penetrating but actually doomed to strengthen with every attack. This siege mentality will ensure that recent events may prevent Sinn Féin making political progress while failing to dent its existing base.
There is a political background to this. The Belfast Agreement offered, in theory at least, the opportunity for all sides to stand down traditional positions and strategies, inviting each to concede something in the interests of a settlement. You could argue, as I did at the time, that unionists acted in bad faith by seeking retrospectively to turn the agreement into a republican surrender. But republicans also refused to stand down their core rationale, based on their sense of being beleaguered in a state run by their political enemies.
What was being offered to republicanism in the Belfast Agreement was not just power- sharing but co-ownership of a peaceful, democratic society. You might say that the true act of decommissioning required of republicans in return was not of bullets, bats and rackets, but of victimology, the standing down of the sense of grievance that had been their driving force.
The republican leaders ultimately lacked the confidence to accept that challenge, and instead encouraged their constituency to cling to a historic sense of victimhood. Their big mistake was believing that the duplicity of their opponents took all the pressure off them - that as long as unionists continued to behave as unionists always had, the republican culture of grievance-based subversion could continue. The IRA could go on, the rackets could go on, the "community policing" too - and, more than that, the nod and wink, the "aren't we the bould Fenian boyos" mentality, could continue.
Republicans have misunderstood the motives of many who supported their right to a voice, misreading a desire for peace as an endorsement of their overall demeanour and ethos. Many of those who worked for their inclusion do not think the Provisionals anywhere near as cute, clever, sexy, bould or even Fenian as they appear to think themselves. There is widespread repugnance of the Jesuitical contortions they have achieved to redraw lines between right and wrong, enabling a settled justification of actions incompatible with democracy.
And there is a growing perception that the corruption of idealism within the movement has vindicated the most apocalyptic prophecies of the Provisionals' most virulent opponents.
These are serious questions in the minds of people who bear Sinn Féin no particular antipathy. If, regardless, republicans wish to continue standing on their claims of victimhood and demands for judicial proof of every suspicion voiced about them, then we, the public, are entitled to draw conclusions. The alternative is for Sinn Féin to emerge from the ghetto and make a significant concession to the disquiet of the world outside itself.