Photography is a less pure art form than painting and sculpture. But it’s now a more important one, says Simon Bowcock. Is photography art? There was a quarrel about this recently in The Guardian. ‘Oh no it isn’t,’ said an art critic. ‘Oh yes it is,’ said a photography writer. Now pantomime season is over here in Britain, here’s a third opinion.

This question is as old as photography itself. It all started as a Victorian argument between photography pioneers and art-establishment traditionalists. Eventually, the traditionalists lost (or died): nowadays photographs are increasingly significant in the world’s major art institutions, such as New York’s Museum of Modern Art and London’s Tate. And despite their inherent lack of uniqueness, works by modern and contemporary photographers such as Edward Weston and Andreas Gursky are regularly auctioned at Christie’s and Sotheby’s, occasionally for millions of pounds. Photography is even an important aspect of the practice of many major artists not usually thought of as photographers, such as David Hockney, Tracey Emin and Gerhard Richter.

It seems facile, therefore, to argue that photographs cannot be art. So why do some still cling to this view?

Photographs are taken by an apparatus directly ‘from life’, the image made not by an artist, but by the light of the world. This leads many to see photographs as straightforward mechanical reproductions of people and things.

But often, photographs are by no means artless, unmediated records of the world, and have instead been subjected to a vast range of artistic meddling: scenic, technical, presentational, contextual, and so on. Some of this interference is occasionally evident in the pictures, as with the intriguing photographs of young Japanese artist Daisuke Yokota. But more often than not, the hand of the artist is not obvious, especially with more straightforward-looking photographs. Even the ubiquitous ‘objective’ approach - flat, frontal, deadpan – is a deliberate aesthetic strategy. But if you can’t see the art in the work, it’s easy to presume that no art is involved.

‘The photograph isn’t what was photographed, it’s something else. It’s about transformation,’ said the American photographer Garry Winogrand, who took photographs ‘to see what that thing looks like photographed.’ Although we might expect it to reveal the world as we think we saw it, a photograph can give an entirely different impression. Viewer perception can be a factor, but more often this is because photographs are both a direct record created by the world and an interpretation created by the photographer’s choices, whether conscious or unconscious. In other words, photographs are both document and art.

This documentary aspect means a photograph can, in a sense, never be entirely art. But ‘part art’ does not equal ‘not art’. Yet many – art critics even – still look at photographs and see all document, and no art.

This duality of art and document – the ‘rendered’ and the ‘real’ - is actually a great strength of photography. It helps explain why photographs fascinate us so much. Another reason they transfix us is their dogged superficiality, which can create great mystery: photographs are all inscrutable surface, all show and no tell. ‘A photograph is a secret about a secret. The more it tells you the less you know,’ said Diane Arbus, a contemporary of Winogrand.

Purely artistic media just do not have these complexities. Even in a photorealist painting, the marks are made by the hand of the artist alone, in no way drawn by ‘the pencil of nature’: it is all art and no document.

And while they can still be potent and have much to say, painting and sculpture today are - comparatively speaking - marginal, arcane activities, practised and consumed by hardly anyone.

By contrast, how many people look at photographs every day? Probably billions. How many people practice photography? Perhaps more than a billion. If only the tiniest proportion of these people are among the most interesting artists of the present and of the future, then photography is set to be by far the most significant and exciting visual art medium in history.

But attitudes in the art world change slowly. So, if we’re still pretending to be stuck in the 19th Century, I’m in 1839 with the French painter Paul Delaroche, who on first seeing a new-fangled photograph proclaimed: ‘Painting is dead’.

Photography’s art/ document duality, its unpredictable and inscrutable character, and humankind’s ever-increasing mass engagement with it, all leave more traditional media such as painting and sculpture light years behind. Since photography is less than two centuries old, and its popularity is only just exploding, we may only be beginning to explore its artistic possibilities. Yet some still fail to see it as an art form at all.

As the same art critic declared a couple of pantomime seasons ago: ‘Photography is the serious art of our time’. Oh yes it is.

Simon Bowcock writes about photographs and makes his own. @simonbowcock