NO ONE could quarrel with the first four words of The Observer's story about Dr Rowan Williams: "The Archbishop of Canterbury". Toby Helm and Julian Coman got that bit unarguably right.

The trouble starts with the next words: "has denounced". "Has" is technically true. The speech they are talking about was, in fact made; but 15 months ago, and reported here and, I think, in The Observer's sister paper, The Guardian, at the time.

As for "denounced", he didn't. He was very careful not to denounce it himself, but to say that other people had done so, and then to give the arguments about why they might be wrong.

Omitting these facts produced a headline and subhead that were just plain wrong: "Rowan Williams pours scorn on David Cameron's 'big society': Key policy 'comes across as waffle', says archbishop of Canterbury in valedictory bombshell".

Nowhere in anything that the paper wrote is there any suggestion that the book being reviewed is a collection of speeches and articles already made. Mr Helm and Mr Coman write, for example, that Dr Williams's "critique of the coalition goes much further than before, arguing that Cameron's supposedly defining concept of the 'big society' lacks any clear definition and is seen by the public as a cover for the withdrawal of the state from its re­sponsibility to the most vulnerable in society".

Again, look at the tense. This is about a speech delivered 14 months ago.

None of this stopped the piece working as a news story, in the sense that it was widely repeated as if it were true. It was followed up by the BBC, the Telegraph (under the rather more truthful headline "Rowan Williams: Big Society is not just 'aspirational waffle'"), The Guardian, Sky News, Metro, and so on.

ALL this got me thinking dyspeptically about a Twitter spat that Ruth Gledhill, The Times's religious-affairs correspondent, had with Richard Godwin, the Evening Standard writer whose interview with Dr Williams I praised last week. Ruth thought it was dreadful. Why hadn't he asked about gay marriage?

"Lots of people with no interest in religion are v interested in ABC views #gaymarriage. Astonishing that u failed to ask," she wrote; and later: "I would be truly ashamed if I got an ABC interview with no p1 write-off."

Godwin responded: "I had been wanting for a long time to speak to him about mutual interests: London, literature, inequality, faith, politics." Ruth replied: "Does the editor of your newspaper know that you hold news in such great contempt?"

This led her to wonder why she has never had an interview with Dr Williams: "If it is cos he fears I will ask difficult questions, I hope and pray his successor has more courage. . . I gave up asking years ago. Looking forward v much to new regime."

Beneath this entertainment is a question that illuminates what journalism can be about. Are we interested in those moments when a public figure can tell the truth, or those where they are compelled to lie? One way of under­standing the distinction between news and features is that, on the whole, news stories are made by getting people to lie, and features by getting them to tell the truth. Of course, a good journalist needs to be able to do both at will.

It's important, if you want to understand the media, to see what is meant here by truth and lying. It's not just a case of saying things that are untrue in the sense that they are factually in­accurate. But when public figures speak, they are engaged in per­formative utter­ance even when they seem not to be. That's what defines them as public figures.

In other words, their words and their actions have to be in harmony, or else they are lying even when what they say is factually true. Their words do not just describe the world: they are supposed to change it.

There is professional pleasure, and skill, in identifying those questions that a public figure cannot truthfully answer and asking them anyway. That's one of the definitions of a good question, as in: "That's a good question. I'm glad you asked that question. Next question, please."

It is certainly the job of any specialist, then, to know which are the questions that cannot be answered with integrity. But I don't think that it's always the right thing to ask the questions that both of you know cannot be answered truthfully. In particular, you should ask the impossible questions at press con­ferences. When there is actually a chance to talk to someone more or less honestly, in an inter-view, it is better to stick to the hard questions, which might make both parties think.