But mothers and fathers make life and death choices for their offsprings dozens of times a day. Is it safe to let them play on the street? Are they sick enough to need a doctor? Should you stop them doing somersaults on the trampoline? Sometimes it seems parenthood is a conveyor-belt of Please Can I's, most of which require a firm No. There are other occasions, though, when the question is outwith your area of expertise or when you'd just be grateful for a bit of back-up. Is it really an abdication of your parental duty, then, to look to an outside agency for guidance or support? Is it a sign of weakness to wish that once in a while someone else would lay down the law?

I'm thinking of the furore over the new Batman film The Dark Knight, which has been classified as 12A (meaning children of any age can see it if accompanied by an adult), but which many parents (and film critics) believe is unsuitable for anyone under 15.

Their complaint – that they took young children to see it only to discover it was full of graphic violence – has been met with apathy from the British Board of Film Classification and high dudgeon from libertarians, who believe it's up to the individual to decide what is appropriate viewing for the under-12s. Any decent carer, they imply, would not rely on something so arbitrary as a BBFC rating, but would do their own research – as if personally vetting feature films was common practice among parents up and down the country.

Well, my first encounter with The Dark Knight came on holiday, where ice cream counters were selling tubs of black and white ice balls with the Batman logo on the front. That, together with the 12A certificate and my memories of the first Batman film, led me to assume the new one would be reasonably child-friendly. If I hadn't come back to a barrage of headlines suggesting otherwise, I would have taken my oldest boys, aged 10 and eight – and I would have watched aghast as bullets flew, blood flowed and the body count mounted. Stripped of all its comic book surrealism, this Batman film is far more sinister than its predecessors, and is the better for it. But for under-12s? You've got to be kidding.

To be honest, censorship is a thorny issue for me. I wasn't subjected to any when I was a child. Occasionally, a particularly raunchy sex scene on television would prompt my grandmother to adjust her glasses and press the off-button. But that was more to ease her own discomfiture than to protect our innocence. As far as books were concerned there were no limits. Which explains why – when asked to recommend one to the rest of my English class – I picked East Of Eden, unaware a novel set in a whorehouse would be frowned on in a Catholic secondary.

I always intended to take the same easy-going line with my kids. But I think life's different now. My children seem to be besieged by images of violence in films, computer games, websites and the news. Almost pornographic in their detail and immediacy, many of them seem to be devoid of context.

This is admittedly not true of The Dark Knight, a sophisticated morality tale in which good, while not exactly triumphing over evil, at least staggers on in the face of it. The message we take home is not the Joker's contention that chaos is thrilling but Batman's that ordinary people, though susceptible to evil, need to believe in the incorruptibility of others. At least that's the intention. The problem facing director Christopher Nolan is the one encountered by Milton in 'Paradise Lost': for all his religious fervour and literary talent, the poet couldn't create a God more compelling than Satan. Similarly, when Heath Ledger explains how he got his smile (his father took a blade to his mouth saying: "Why so serious?") or reveals why knives are his weapon of choice: "Guns are too quick. You can't savour all the little emotions," he lights up the screen. When Christian Bale pontificates it's a struggle to keep your eyes open.

There is also a contradiction between the central premise – that killing people is wrong – and the apparent glee with which violent acts are portrayed. The Joker made a pencil "disappear" by smashing a man's head into it and some people laughed. Just like my eight-year-old may have laughed when he stumbled across the image of a man's head being blown off as he inflates a dinghy, found on YouTube at a friend's house a few weeks ago. Do you think the picture was real, I asked him? Probably not, he answered without conviction.

And that's what worries me: not that my children will be disturbed by the images in The Dark Knight and elsewhere, but that, in the end, they won't. That the high quality of the special effects and the blurring of the boundaries between the genuine and the fake will make it impossible for them to distinguish between fantasy and reality. And that, at some point, the distinction will cease to matter.

OK, so I know it's my responsibility to make sure that doesn't happen – and I haven't shirked it. My verdict has been delivered and accepted, albeit with a degree of sulkiness. But I appeal to the BBFC: next time a film that contains scenes of explicit violence crosses your path, stop worrying about box office takings and put your foot down. Just for once, I won't have to.

Dani Garavelli will be online to discuss these views at 2pm today. Leave your comment - now - and check back later for the live discussion.