Joan Smith: Venus is the difference between nudity and porn

Did they consider a fig leaf? The Victorians made one for Michelangelo's David, and I'm sure someone could have come up with a version to protect the modesty of both Cranach's Venus and the delicate sensibilities of travellers on London's Tube trains. Two days ago, Transport for London suddenly reprieved the goddess of love, who had earlier been banned from advertising the Royal Academy's forthcoming exhibition of the work of the 16th-century German artist. It followed a similarly abrupt change of mind over a poster for a dance show in which a muscular naked man clutches a cuckoo clock in front of his genitals.

This isn't the first time a female nude has been censored in this country. A few years ago, a poster for Opium perfume featuring the model Sophie Dahl in an odalisque pose was removed from advertising billboards, no doubt saving the lives of hundreds of drivers who were so unfamiliar with female anatomy that they would otherwise have crashed their cars.

I don't know how many times I need to point out that not every single image of a naked woman is exploitative; I loved the Opium poster and I love Cranach the Elder's pale nudes, especially the one TfL apparently considered offensive. She's wearing nothing but jewellery and holding a wisp of gauze, neither embarrassed by her nakedness nor showing it off; the image isn't even as overtly sexy as Kylie in one of her stage costumes or Victoria Beckham on just about any day of the week.

That, I suspect, is the problem. We're so used to pornified images of women, pouting from the covers of men's magazines or writhing on MTV, that a naked woman who doesn't fit into those categories is disturbing. Venus's unadorned, surgically unaltered beauty is an unfamiliar sight these days; Cranach would have been bored by WAGs and movie stars, who appear to have been cloned in some factory in Hollywood or Essex. The idea that the poster is offensive is risible, but it also says something about a society that is balanced precariously between the chasms of exploitation and puritanism.

We live in a frankly sexual culture whose images of scantily dressed women are irritating not because they involve nudity – most of the time they don't – but because they're intended to satisfy basic male appetites, regardless of the fact that a lot of men don't actually like them.

At the same time, religious groups are making increasingly noisy demands that their taboos should be observed by the rest of us, which may be what TfL had in mind when it explained the thinking behind its short-lived ban on the Cranach Venus: "We have to take into account the full range of travellers and endeavour not to cause offence in the adverts we display."

Avoiding offence to the millions of people who use the Tube every day is a patently absurd ambition, and any attempt to fulfil it is bound to result in the kind of baffling, inconsistent decision-making we've just seen. The last thing we want is a situation in which minorities (or assumptions about minorities, which is even worse) are allowed to dictate what isn't acceptable to the wider population.

Many of us don't like the coarse attitudes to women and sex that have invaded contemporary culture. We don't like the way Premiership footballers behave at parties, the huge commercial sex industry or the fact that about 11 per cent of the male population use women who work as prostitutes. But that's an argument against sexual exploitation, not against celebrating the human body. Fig leaves and their modern equivalents are always products of fear, not respect for women.