It's our heritage - but at what price?

I would love to have been present for Nicholas Serota's speech to the Saving Art for the Nation conference the other day, and not merely as a connoisseur of heretical utterances. The conference had been organised by the National Arts Collections Fund, the charitable organisation that helps museums to acquire works for their collections, and Serota's speech questioned the kneejerk instinct to prevent the export of works of art. On the face of it, it was a bit like the keynote speaker at a League Against Cruel Sports annual conference standing up and saying that not only do foxes enjoy the chase but the hounds only catch the crappy ones. I like this idea a lot - not because I hate foxes, but because I dislike righteous certainty and there's always something delicious in watching a sacred cow being overturned. I'm sad to say that Serota's speech wasn't quite as sacrilegious as all that. The conference had been intended to consider matters of principle as well as practice, and its rubric doesn't rule anything out of bounds. So nobody could fairly accuse him of a breach of etiquette.

Still, it's one thing to think a thing and discuss its abstractions over coffee. It's quite another to break ranks and say it in public, and there's no question that the National Arts Collection Fund is essentially wedded to the philosophy that keeping things here is better than letting them go abroad. A centenary show currently at the Hayward Gallery, devoted to works that it has helped to acquire for the nation, is called Saved! - the exclamation mark recalling the title card of a silent cliff-hanger. The implication is clear. There lies a struggling Old Master, roped to the tracks by a villainous art dealer while the locomotive of a foreign gallery thunders towards it. And then, just when all seems lost, the National Arts Collection Fund swoops in to rescue it from a fate worse than death.

Other people have questioned this storyline before - usually supporters of free-market capitalism - but not many pillars of the art establishment have taken it on. And in some spheres you can see that suggesting anything else is almost unthinkable. In a consultation document published in July, the Goodison review - set up to inquire into the efficiency of "support to regional and national museums and galleries to help them acquire works of art and culture of distinction that otherwise might be sold abroad" - drew up a list of questions that were entirely concerned with the mechanisms for keeping fine art in the country and not at all with whether that end was a sensible one.

The usual argument advanced by zealous "savers" is that they are preserving the national patrimony, though patrimony often turns out to be a wondrously elastic term. Take the National Gallery's Madonna of the Pinks, the latest maiden in peril to make a claim on the Lottery Fund and susceptible art lovers. Raphael's painting only entered the country in 1853 - as part of a rich toff's job-lot buy - and it then languished in obscurity for years. What patrimony does it represent, other than a 19th-century tradition of scooping up other people's masterpieces? And if that's the element of British history and culture it represents, it seems perverse to suggest that it is unconscionable that a rich US institution should buy it now. What's often concealed beneath the arguments about "national heritage" and "aesthetic value" is old-fashioned, jingoistic snobbery. When our chaps buy abroad, it's connoisseurship; when Johnny foreigner does it, it's vulgar acquisitiveness.

Sir Nicholas has already been accused in some quarters of special-pleading. How surprising, his opponents say sarcastically. He wants less money to go on Old Masters and more on contemporary art! Could this have anything to do with his position as the director of one of the world's leading galleries of contemporary art? Well, possibly. But such responses hardly answer what's at the core of Serota's argument, which is that cultural stag- nation is no better than any other kind. There's a perfectly respectable case for saying that more art should change hands, not less - and in this I would probably go a bit further than Serota, who is currently trying hard to buy Sir Joshua Reynold's painting Omai for the Tate. This painting has a far better case than the Madonna of the Pinks for being an irreplaceable part of our cultural heritage, but the idea that it can only possess that quality if it is actually on mainland Britain seems to me intellectually dubious. It would be nice if the Tate, rather than a foreign buyer, can pry it out of its anonymous seller's hands. But if it can't it won't be a national tragedy - and it might have unexpected cultural effects in its new home, just as countless Italian and French paintings have had here.

The truth is that culture and stasis are not natural companions. Most discerning art collectors know it is a bad idea to find a place for each work and leave it there in perpetuity. Familiarity gradually makes it invisible, a mere part of the architecture. Your ability to see it decays and can only be refreshed either by putting the piece away or moving it alongside new neighbours. It's an argument that's rarely applied on a larger scale - but it is no less true across the centuries or across continents. For great art to continue to move us, some of it occasionally has to move - to a culture that values it more at the time or even - and here's a real heresy - to one that can simply afford to put a higher price on it.