He was a skilled practitioner of the art himself, of course. During the war, a psychological profile of Hitler which was prepared by the United States commented on the dictator's "primary rules", which it outlined thus: "Never allow the public to cool off; never admit to a fault or wrong; never concede that there may be some good in your enemy; never leave room for alternatives; never accept blame; concentrate on one enemy at a time and blame him for everything that goes wrong; people will believe a big lie sooner than a little one; and if you repeat it frequently enough, people will sooner or later believe it."

George Orwell made good use of Big Lie Theory in one of his most famous novels, 1984. He described it as the ability "to tell deliberate lies while genuinely believing in them, to forget any fact that has become inconvenient, and then when it becomes necessary again, to draw it back from oblivion for just so long as it is needed".

Elsewhere in the book, he wrote: "Applied to an opponent, it means the habit of impudently claiming that black is white, in contradiction of the plain facts."

Brian Cowen, Fianna Fail's own Big Brother, performed his own take on the Big Lie theory during a speech at the Humbert Summer School in Mayo last weekend.

The speech was mainly a rant against Fine Gael, and on first reading raised an obvious question: what's the point of summer schools if people are invited along merely to make party political speeches? We can hear those in the Dail. Summer school speeches should be about ideas and philosophies and ideologies and intelligent argument.

Instead, Cowen went into general election mode precisely three months after polling day, and began bashing Fine Gael with the same gusto he had brought to the task last May.

Perhaps for that reason, it was comments he made in his speech about the media which generated the most attention.

Although the political part of his speech ignored how Fianna Fail had come within a few seats of losing the election, despite all the advantages it enjoyed in terms of incumbency, control of the purse strings, and experience of government, Cowen's party did manage to scrape a win.

The Tanaiste's sneering triumphalism can partly be justified by the result, therefore. When he came to attacking the media, however, Cowen rewrote history to such an extent that he showed himself to be an expert practitioner of the Big Lie. He impudently claimed that black is white, in contradiction of the plain facts.

Cowen does seem to genuinely believe his own nonsense, something Orwell suggested was important to The Big Lie Theory. His argument, put in black and white terms, is that the media was biased against Fianna Fail and for Fine Gael during the election campaign. The speech to the Humbug Summer School is littered with references to these perceived biases. Early on he refers to a "picture of at times relentlessly negative coverage for Fianna Fail" and an "equally clear" pattern of soft coverage of Fine Gael and its leader Enda Kenny. He referenced two "analyses" of election coverage, one by RTE and another by a small outfit called Media Matters which he said proved his contention of bias.

Three thoughts suggest themselves at this point. Firstly, RTE's handing of the general election so favoured Fianna Fail at important moments in the campaign that any suggestion it now makes about bias should be treated with great caution.

Secondly, Cowen appears to be unaware or uninterested in the difference between vigorous journalistic investigation and propaganda, between reporting the facts and promoting agendas. He seems to believe that asking legitimate questions about the Taoiseach's dodgy financial past is a sign of bias.

Thirdly, if he really wanted to examine bias during the election campaign, why did he not mention the many media favours that were done for Fianna Fail in April and May? These ranged from the aforementioned prejudices of the national station to the carefully crafted propaganda in the country's biggest newspaper, the Sunday Independent, in return for which one of its columnists was made a senator by the Taoiseach.

Cowen had a small point in his speech when he brought up the media response to the debate between Bertie Ahern and Enda Kenny a week before the election.

"The general failure of the media to understand the impact of the debate should raise more questions than it has, " he said.

"Leaving aside the few who actually called the debate for Enda Kenny, the consensus was that nothing much had happened. The Irish Times led with 'Kenny Scored On Confidence And Ahern On Detail' and the Irish Independentwith 'Ahern Shades It But Fails To Land Knockout'."

Those headlines (and it's hard to see anything fundamentally wrong with either) were written late on the night of the debate, with a deadline approaching, and reflect a reluctance on behalf of the newspapers concerned to make a definitive call in the heat of the moment and under pressure. Having had time to digest the debate in the following days, journalists writing about it allowed that the victory for the Taoiseach was more clearcut than at first suggested.

But the original error, such as it was, was not the result of bias, or of the media being out of touch, something Cowen also suggested could be the case. It was borne of a genuine reluctance to come down too heavily on either side without proper time for assessment of the debate.

In Fianna Fail, however, the Big Lie has it that the media is always and forever against it.

The lie was propagated by party workers and public representatives during the campaign, by a slightly squiffy Bertie Ahern on the night of the election campaign and by Brian Cowen at the Humbert School last weekend. It will not be the last time you hear it. If they repeat it frequently enough, people will sooner or later believe it.