The old joking reply to Brendan Corish's unfortunate slogan when he led the Labour Party in the late 1960s - "The '70s Will Be Socialist" - was "The Socialists Will Be 70". It's not quite a joke any more.
In the 1960s when the term "generation gap" was invented, it described not just a gulf between the young and the old, but the nature of that divide. The young were open-minded, adventurous, tolerant, energetic. They were not taken in by the stifling orthodoxies of church and state. And they were mad as hell.
Their elders, meanwhile, were all of these things with the addition of the word "not". Stuffy, tight-arsed, blinkered, in thrall to stale ideas and stupid hierarchies that survived only because of misplaced deference, they hated the young and free simply because they were old and enslaved. And they were as timid as postulants.
These were of course stupid generalisations. And like most stupid generalisations they were partly true. There was a historical moment - the '70s in Ireland, the '60s everywhere else - in which youth took control of the political and cultural agenda and its values were deeply shocking to anyone over 40.
It was a particular time when certain kinds of utterance - a student calling a bishop a moron on live TV, for example - were not just ways of seeking attention or of being bad-mannered, but expressed a profound division between the past and the future. The absolute horror that such a moment caused many, and the utter joy it gave others were both utterly sincere. When equal and opposite reactions are also equally authentic, the reality of a generation gap cannot be denied.
The problem, though, is that this experience inserted into the long list of generally-held assumptions the belief not just that there would always be a generation gap but that it would always take this kind of shape. The young would always be bold and questioning. The old would always be set in their ways.
Young is thus better than old. If you're running a company or scheduling a TV station or marketing a product or looking for candidates, you want young people. Things that by and large don't interest young people - opera, plays written any time before 2003, political discussion programmes - are either by definition bad or give at best equivocal pleasure because they are continually surrounded by the nagging question: "What can we do to attract more young people?"
So strong are these assumptions that no one seems to notice that, in Ireland at least, old is the new young. There are of course lots of 70-something reactionaries and lots of 20-something radicals. But if you want to find a typical group of people who've seen through orthodoxies, challenged assumptions and opened their minds - if, in particular you're looking for people who are mad as hell - a dip into the grey pool is likely to be more productive.
Look around the public gallery at the planning tribunal, for example, at all those people who are cheering Tom Gilmartin, upsetting protocol and expressing their rage at the corruption and injustice of their country. Very few of them will see 60 again. Yet whatever else they are, they are not complacent and blinkered.
They go because they want to know, to find out the reality behind the official world in which they lived. Look, on the other hand, at the smug cheerleaders for the Best Little Country in the World who keep telling us to forget the unfortunate aberrations of the past. They're likely to be half the age of the angry brigade.
The reasons are obvious enough. It's not just that the oldies were, after all, shaped by the Paris revolts while the youngsters were shaped by Reagan and Thatcher. Much more importantly it's that the older people have learned lessons about power and authority in this country from bitter experience.
They're the ones who paid penal taxes because they were told that the country was in trouble and we were all in this together, and then discovered that those in the know were falling around laughing at their innocence. They're the ones who tried to be good Catholics even at the cost of having more children than they really wanted only to find that some of the preachers were into vile practises. They're the believers who have been betrayed. And there's nothing quite like betrayal to make you vigilant and sceptical.
Perhaps the most eloquent expression of the assumption that young is good and old is bad, though, is the prevalent notion that the tribunals and investigations are a silly indulgence because the late 1980s and early 1990s are so long ago. If you're 25, 15 years is a mighty long time. If you're 65, it's not. Why should the perspective of the 20-somethings be automatically regarded as more valid than that of the 60-somethings?
It is the much-patronised tribunal-watchers who have given dignity and meaning to a process whose integrity has otherwise been corroded by cynicism and greed. And if they take power with a packed lunch in one hand and a fold-up umbrella in the other, so much the better.