When their failures return to haunt them, leaders of opinion often comfort each other with the promise that, given one more chance, they won't make the same mistakes again.
I wish it were so. But, in a week in which we are confronted with a dismal reminder of the failures of 1983 and 1992, and the wasted years since the X case, it doesn't look like it.
The Government has taken fright at the prospect of re-entering the battleground of abortion and, in an effort to avoid the issue, is prepared to set off on a more roundabout route than before.
A Green Paper leading to months of public debate; private discussions at the all-party Constitutional Review Group; legislation agreed, drafted and put first to the Dail and Seanad, then to the electorate in a referendum . . .
The distinguished lecturer in law Gerard Hogan describes this course, which Brian Cowen outlined to the Dail on Tuesday, as arcane and complex.
If it were followed, it would prolong, confuse and frustrate the search for a solution which has eluded politicians, lawyers and doctors for 15 years. It will do nothing to reduce the bitterness which the issue invariably arouses.
But the bandwagon is rolling; it has been rolling for some time.
Long before the presidential election, county councils had been canvassed for support by groups demanding a referendum. The election gave them an opportunity to drive their message home and, rightly or wrongly, strong support for President McAleese and Dana allowed them to claim the tide was turning in their favour.
If at first the Government pretended not to notice, the events of the week have forced its members to turn again to issues which they and some commentators foolishly believed to have been successfully dispatched.
Yesterday the three Independent TDs on whose support Fianna Fail and the Progressive Democrats depend began to turn on the heat, reminding Bertie Ahern and his colleagues of promises made during or after the election.
In the election Mildred Fox, Harry Blaney and Jackie Healy-Rae enjoyed the backing of many who'd felt let down by Fianna Fail in its pursuit of a new generation and a new constituency. Now the Independents are likely to have been told that, to coin a phrase, it's payback time.
The political opportunity - and the shameful reminder of old failures on all sides - came with news of the rape and pregnancy of a 13-year-old, which has prompted debate in many quarters and on a variety of social, legal and ethical issues.
It will indeed be of concern to many, but none will be more painfully affected than the girl and her family, hurt first by a terrible assault, then by the kind of exposure they should not have been forced to endure.
It's for her and her parents to decide what is to be done. They should have the benefit of professional advice, not the pressure of zealous persuasion; and, once freely made, their decision should be respected.
Much has been said and written about the case, but the wisest words were those of Fintan Farrell, speaking for the Irish Travellers' Movement. He complained that journalists had erred in their coverage, which came close to identifying the girl and her home.
Was this, he asked, because she was a traveller and not, as in another case which had been given a great deal of publicity, the child of a middle-class family? It's one of many ethical questions which call for a serious response from media organisations and from journalists.
Fintan Farrell properly distinguished between issues relevant to travellers, such as the condition in which the family lived, and questions which fall to be answered by the authorities - judges, lawyers, the Eastern Health Board (which has custody of the girl) and the Government.
Indeed, whenever we are confronted with a case like the present one - some, we must assume, are not brought to our attention - the reminders of 1983, 1992 and the wasted years during which government after government reneged on obligations to legislate are painful and shaming.
Not only did governments fail to legislate, but commentators, who ought to have badgered them until they did, allowed the politicians of all shades to get away with it. While the going was good, no one wanted to interrupt the party by asking awkward questions.
And awkward issues were avoided.
Even now it's worth reminding ourselves how we got into the mess. How, in the early 1980s, opponents of abortion refused to accept that the law which had served since the middle of the 19th century was sufficient to meet what they believed to be the threat of change.
But they didn't trust those whom they'd elected to represent them and insisted on a constitutional prohibition, which couldn't be changed without a referendum. Against the advice of the attorney general of the day, Peter Sutherland, they also insisted on their wording to express the ban.
But the ban was baldly stated and the legislators, fearing the zealots even more than their predecessors had feared the bishops, failed to legislate. And in the X case the Supreme Court's judgment interpreted the words in a way that took the authors and their friends by surprise.
Coincidentally, one of the authors' friends who complained at the time was Mrs McAleese, on whom the obligation of referring the Bill to the people will fall - if the "arcane and complex" course proposed by Mr Cowen is followed.
When those who'd refused to trust members of the Dail and Seanad decided that they couldn't even trust the Supreme Court, the last Fianna Fail-PD coalition arranged three further referendums to coincide with the general election in 1992.
The right to information on abortion and the right to travel outside the State were made clear, which is why the 13-year-old in the present case could seek an abortion in Britain if she and her parents so decided and she was in their care.
One of the many questions which Mr Cowen failed to answer in the Dail was about the role and obligations of the Eastern Health Board.
The fact that the proposal on the so-called substantive issue was rejected in 1992 - and there has been no legislation - is the reason for the preparations being made for yet another attempt to secure a ban on abortion on their terms.
When he was challenged about his position on the radio the other night, one of the most persistent campaigners, William Binchy, explained that, really, it was a question of philosophy.
It sounds more like theology to me.
The great John Kelly once explained the difference to a bemused audience of Fine Gaelers.
Philosophers, he said, would go to the ends of the Earth to discover the truth and when they found it they'd be prepared to live with the consequences.
Theologians believed they knew the truth, and if they went to the ends of the Earth it was only to get back to where they began.