What if Gerry isn't lying, but just hasn't got a clue what's going on?
The Sinn Fein leader is a political relic from another time and place who is simply unable to adapt to the new reality
Francois Hollande will not be the Socialist Party's candidate in next year's French presidential election.
With popularity ratings as low as 5pc at various points over the last couple of years, the current resident of the Elysee Palace had as much chance of surviving that fight as a blind mouse in a cats' home. Electoral politics is no respecter of status. His colleagues made him stand aside.
That's what happens in normal democratic systems. Even Margaret Thatcher eventually got that late-night visit from the men in grey suits, telling her that the game was up. The Iron Lady may have won three elections in a row, but once a fourth victory for the Conservatives was under threat, she was cajoled to do the right thing by the party. Being a democrat, she did.
Not so in Sinn Fein. In that party, leader Gerry Adams can repeatedly drag his colleagues into a mess not of their own making, scuppering any chance the party has of leaving its murky past behind, but no one challenges him; no one stands up to him; no one dares echo the words of Oliver Cromwell ejecting members of the Long Parliament in the 17th century: "You have sat too long here for any good you have been doing. Depart, I say, and let us have done with you."
Adams's continued leadership is an experiment in what happens when you don't get rid of a leader who has either gone rogue or lost touch with mainstream opinion, but stick loyally by them instead.
Do they learn from their mistakes or continue to make more of them? Do they become more careful or increasingly careless? The example of Adams suggests that they go from bad to worse, dragging you into a sequence of ever-deepening crises for which there's no obvious solution.
Gerry has been saved time and again from the consequences of his own pratfalls only by the blind loyalty of craven toadies in his party; or perhaps by their failure of nerve, not knowing what would happen if the southern tail tried to shake the northern dog. The North got rid of Adams once. It wasn't part of the deal that the south would endeavour to give him back.
It's not simply that his handling of questions about the extent of his knowledge of the murder of prison officer Brian Stack more than 30 years ago has been so inept, even though that alone would have been sufficient to finish off the career of the leader of any other political party.
It's that there's now apparently nothing that Adams can do which will embolden his colleagues to tell him some hard truths - namely that he's not up to the job any more.
That he's lost it. Indeed that the "it" he had, and which served him well enough in the North, may never have been the right "it" for the job he needed to do in the Republic. That's the real calamity for SF. This was an avoidable disaster. It's rooted entirely in the failings of Adams's character.
His is a very Shakespearean story, one in which the tragic hero's downfall comes, not from external forces, but by the way the person that he is reacts to those external forces. The external force right now is the pressure that he's under thanks to the dogged determination of Austin Stack to do the right thing by his murdered father. The added component that makes the mixture so combustible is Adams's reaction to that pressure.
He's unable to get enough people to believe his version of events, because he has acquired the reputation of being economical with the truth; like the boy who cried wolf, he now wouldn't be believed if he genuinely did see a whole pack of wolves approaching.
For SF's part, that problem looks unfixable. As long as it has him as leader, it will have a leader widely regarded as an habitual liar. Worse, it may not even matter if Gerry Adams is telling what he considers to be the truth, if his memory itself is systemically unreliable, and there's plenty of evidence to suggest that it is. What if the real reason that he is unable to provide a coherent or consistent narrative about what he knows is because he genuinely does not remember it in sufficient detail?
It's a cliche that a liar needs a good memory, but sometimes not having a good memory can make it seem as if you're a liar even when you're not. It's simply that your ability to grasp detail is impaired - and here, detail is all.
Adams has a poor command of detail in general, as can be seen when he's put on the spot about specific matters of policy. Consider his infamous interview with Sean O'Rourke about personal taxation rates as Exhibit A .
This doesn't count so much on questions of finance or transport, which can be farmed out to more competent members of SF; but when it comes to issues of life and death that only he can deal with because they touch on his own history, and which concern other people to whom those events matter very much, such as the Stacks, the problem is multiplied if Adams, when asked to clarify facts, is running on empty.
It makes no sense whatsoever that he would claim to have been given certain names by Austin Stack, because Austin could refute his allegations immediately; but then it makes even less sense that Austin would have given him the names, as the entire purpose of the meeting was to get information from SF and the IRA, not the other way round. They were not coming to the republican movement from a position of knowledge which they wished to share with the IRA; the IRA already knew who planned and carried out the shooting of Brian Stack.
They were going to them as frustrated people who had hit a brick wall in their own enquiries, and now, as a last resort, were imploring republicans themselves to share what information they had.
But if Adams does not actually remember the exact sequence of events, but is merely trying to make sense of them in retrospect, then it makes perfect sense that he would, as he has on so many previous occasions, alight on little bits and pieces of information, like a magpie picking up shiny things in the grass and building a nest from them. Being asked afterwards to recall where all the fragments came from is impossible.
This method was demonstrated again in his Morning Ireland interview with Audrey Carville on Friday. It's not that he embellishes his narratives so much as that he tries to give them added veracity by introducing extra elements which only serve to make his account seem slippier than ever.
On Friday morning, Gerry practically made it sound as if he and Austin were collaborators in a joint venture to find the truth, bound by the same "confidentiality agreement", and driven only by a shared desire for justice.
"The two of us sat down" and "worked out a process" was how Adams put it, painting a picture quite at odds with the reality of a private citizen approaching a powerful leader of the republican movement in an effort to break down a wall of silence. That is not a relationship of equals, much less a partnership.
But that's typical of Adams. He's always trying to play two contradictory roles at the same time. On the one hand, the strong leader who brought SF/IRA through the long war; on the other, the victim who has also suffered every bit as much as the Stacks. On the one hand, the democratic politician with the same respect for the law as every other TD; on the other, the man bound by loyalty to keeping the secrets of a deadly illegal gang.
It's when he's asked to reconcile these two elements - as when Carville asked him whether he would give the name of the IRA member who met the Stacks - that the carefully constructed facade falls apart. He cannot keep playing both roles, but nor can he pick between them. He's trapped.
The look on Adams's face when Austin Stack appeared at the press conference in a Dublin hotel last week and directly accused him of being a liar said it all.
He was annoyed, but there was bafflement, too. He literally does not seem to understand what's going on.
If you've lived a lie for a long time, a secret life, some details of which must be kept even from people who are closest to you, then you need to retain control at all times. When it starts to slip is where the "rabbit caught in headlights" look comes from.
Adams is also something of a gambler, in the Donald Trump mould; he will risk an extra detail here or an off-the- cuff remark there by playing the percentages. Nine times out of 10, you get away with it. For the one in 10 times that you don't, improvise. When no consequences are imposed by those behind you in the party, there's no incentive not to bet the farm the next time either.
One texter to Newstalk last Friday, while no supporter of Sinn Fein, felt that using the murder of Brian Stack as a stick with which to beat Adams was to impose the standards of 2016 on to events of 1983 - but that's what happens when you try to impose the leaders of 1983 on to the political situation in 2016. They bring 1983 with them.
Adams is a relic. He is a 20th century politician struggling to keep his feet in a 21st century world. That's not a judgement on his age, but on his abnormal longevity at the top of a movement which does not allow dissent. Gerry lives in a world that no longer exists except in his own head.
In modern politics, nostalgia is no substitute for nous.