Tom Sutcliffe: Why we change the crime to fit the story

Social Studies: We want life to have significance – and so we're eager for details that make sense of the senseless

At least Max Clifford and the father of Meredith Kerchner have a good excuse. Both men have recently delivered categorical pronouncements on the guilt or innocence of a person under the shadow of legal proceedings.

In Clifford's case it was Shrien Dewani, accused of procuring the murder of his wife while on honeymoon in South Africa, and Mr Clifford's excuse was that protesting Mr Dewani's innocence was exactly what he was being paid to do. In the case of Meredith Kerchner's father, interviewed recently as Amanda Knox's appeal hearings began in Italy, the excuse was parental grief – which seems fiercely defensive of the idea that his daughter was killed by three people rather than just one. He was openly outraged by the idea that Knox should attempt to prove her innocence – as if her guilt was one of the few consolations left to him. And if you were judging their take on these matters I suppose you'd note first that they're both interested parties.

We're all interested parties of course, and not just in the sense that these two stories have proved utterly gripping in their unfolding. Because we rush to judgement as well, and are tempted to do so by our appetites for a particular kind of narrative.

You could see this at work most dramatically after the recent arrest of Julian Assange, with his detractors apparently deciding that any crime would do and his sympathisers reflexively jerking in the other direction, so that the women who have laid charges against him were pre-emptively (and on virtually no evidence in either direction) declared guilty of false accusation. Lip service was paid, on both sides, to the conceptual difference between an allegation and a fact – but it was clear that a lot of people had made their minds up in advance to go with a storyline that matched their politics.

In cases like that of Amanda Knox and Shrien Dewani, our motives are less obvious. The South African Tourist Board might understandably favour an explanation that depicts the event as almost unprecedented rather than typical, but that's neither here nor there for most British readers.

What does matter to us is our appetite for the story itself. To put it bluntly, if Anni Dewani's murder was a random act of violence by two township thugs, it's far less engrossing than if it was a pre-planned hit – just as it was more "interesting" for Lindy Chamberlain's baby to have been sacrificed in a cult ritual than snatched by a feral dog.

We want life to have significance – and so we're eager for details that make sense of the senseless. And newspapers know how to feed that. Yesterday it was reported that CCTV images of the Dewanis shortly before the murder had emerged: "Shrien keeps his hand in his pockets and makes no physical contact with his new wife, who walks silently behind him with her head bowed", read one press description, and thus utter banality was slyly called on behalf of the prosecution.

To be honest I'm no better than anybody else at resisting the temptation of this kind of thing. I have my convictions. But I do try and remember that, for the moment, they have almost nothing to do with admissable evidence. And that innocent people can get trapped in a good story.

Mona Lisa smiles on my prediction

It's been a bumper year for Mona Lisa stories – that irresistable flypaper for the attention-seeking academic. They began, in January, with the suggestion that the model for the painting had suffered from high cholesterol, which was almost immediately followed by the proposal to disinter Leonardo himself, so that theorists could check out their notion that the picture was actually a disguised self-portrait. I wrote at the time that I doubted that we would"see 2010 out without another theory being added to the swarm that buzzes around her".

In the nick of time Silvano Vincenti (who was also involved in the plan to dig up Leonardo) has ensured that it wasn't a false prediction. A lesser man might think that one contribution to far-fetched Mona Lisa studies was enough for one year. But Signor Vincenti has not let his imagination rest on its laurels. Now he's suggested that Leonardo painted a secret cipher into the eyes of the figure, including the letters LV in the right pupil.

These are, naturally, only visible under magnification and only, I strongly suspect, if you look with the eyes of faith. Vincenti also publicised thetheory this year that Caravaggio was poisoned by lead in the paint that he used – but I'm glad to see he's returned to the mother lode now. I won't risk a prediction about exactly how far we will penetrate into 2011 before his next sensation. But I bet it won't be long.

Banning cocktails is completely pointless

The US Food and Drug Administration has effectively banned Four Loko, a turbo-charged alcopop which, after hospitalising a number of its consumers, generated its own prohibition panic in the US. Authorities were worried about its combination of high levels of alcohol with stimulants such as caffeine.

Frat-boys, by contrast, loved this cocktail and competed with each other to see how many they could drink before lapsing into unconsciousness. Quite what the FDA thinks its ban is going to achieve I'm not sure. It took Google 0.18 seconds to produce 339,000 results for the search "Four Loko Recipe" – an emetic-sounding blend of boiled sweets, caffeine tablets, malt liquor and Sprite. Will bathtub Four Loko really be any less hazardous than the real thing?

t.sutcliffe@independent.co.uk