With pictures of the dying Princess rumoured to be for sale, Raymond Whitaker asks where the line should be drawn With rumours that pictures of the dying Princess are on the market, Raymond Whitaker asks what is the morality of shocking images, asks
"I feel uncomfortable at the moment about being a photographer," Don McCullin said last week, "but there are bad elements in every profession - bad lawyers, bad doctors. There is a small minority of bums among photographers as well, but it is very unfair on the rest of us. Since its invention, photography has rendered great service to society in many ways."

Try convincing the world of that when pictures of the dying Diana are rumoured to be on the market. Editors everywhere have vowed that they would never use them, probably wisely: they would be lucky to escape lynching by an outraged public if the horrifying descriptions of the photographs circulating among the journalistic corps are accurate.

Sooner or later, though, the price may fall and an editor's nerve may rise sufficiently for the pictures to be printed somewhere - Italy, say, or Greece or Mexico. It would be seen as the final and worst violation of privacy in a life that was arguably cut short by our intrusion into it.

But at the Barbican in London this week, McCullin, the greatest war photographer of his generation, will be showing a close-up of a dead North Vietnamese soldier, one eye open, the other closed, his possessions scattered around him. It is a powerful image of the violence and waste of war, but there is no question that the dead man's privacy is being stripped away.

Does this put his photograph on the same level as the ones of Diana, if they exist, or is it a matter of context? Do the motives of the photographer matter? The answers are no, partly, and yes.

McCullin's picture will be on the wall of a hushed gallery, part of a retrospective exhibition of his life's work. If the last photographs of Diana ever see the light of day, it could be on a page next to an ad for laxatives. Context is important: McCullin himself raised the subject of the controversial Benetton billboards which used images of an Aids sufferer and of a Mafia murder victim being mourned by his family to sell sweatshirts. "It was despicable," he said.

What the Benetton case shows, however, is that the motives of the publisher matter too. The photographers who took the pictures used by Benetton never meant them to be used in advertising; McCullin burned to show the misery and inequality of the world to comfortable readers of the Sunday Times magazine, but his photographs sat awkwardly among fashion features and Volkswagen ads. The contradiction became too much, and the Sunday Times let him go.

Time and distance play their part in determining how much reality we can take. McCullin's dead Vietnamese is sufficiently far from us, both geographically and in time - the picture was taken in 1968 - to spare our revulsion. But come too close on either scale and the public objects, as the Observer found when it published a photograph of an Iraqi soldier incinerated to a scarecrow shape during the Gulf War.

It was a brutal image of what happens in such conflicts, but it was too much for many readers. No one would expect a similar response, however, if a picture were to be published today of the dying Archduke Ferdinand in Sarajevo in 1914.

It is also a question of identification - we never knew the dead Vietnamese, and his relatives would be extremely unlikely to see the photograph. The same goes for Archduke Ferdinand. But we all knew Diana, or felt as if we did, as the past week has dramatically proved.

Why force such unpleasant images on people anyway? One reason McCullin would cite is to show what violence is really like, rather than as it is depicted in the movies. That is not to say that his pictures are not also dramatic: they are, but for a different reason - the people in them have more to worry about than having a lens pointed at them. Contrast this with the subjects of the paparazzi's attentions, who are all too aware of the camera. They simply want to choose when they are photographed, while the paparazzi contest their right to do so.

McCullin insisted on consent. "When I was in the presence of grieving sons or daughters or parents," he said, "I always tried to exercise the utmost dignity, to respect their sorrow above my work. I always looked at their eyes for approval before I took a photograph." People were executed in front of him, but he never photographed them. "It would have been impossible to get proper consent."

Paparazzi are not interested in consent, but before dismissing them as scum - "bounty hunters", McCullin called them - we might consider whether they serve any purpose in exposing the hypocrisies and vulnerabilities of public icons who appear to affect the way some people live their lives. Look at the Hollywood names who condemned the paparazzi last week, among them Sylvester Stallone. Is it relevant that many fighters in Chechnya have pictures of Stallone as Rambo on their gun-butts?

The problem is that in recent years the stars, the paparazzi and the people who publish their photographs have lured us all into a great celebrity binge, in which infidelities, new artistic projects, drug-taking and deal- making are swallowed up in one great orgy of publicity. McCullin was paid a fixed salary for covering wars, but this is an industry in which one photograph can be worth pounds 100,000.

Last week Britain was said to be in a sober mood. It was desperately avoiding the slightest upset - the spy spoof film Austin Powers is hastily re-edited to exclude Di jokes; Mercedes pulls its ads; whole runs of magazines are pulped. How long, though, before we reach for another fix of fantasy?

Diana sometimes played her part in this circus, using the paparazzi, for example, to signal that there was a new man in her life. But she could not control them, any more than they could themselves, and in the end they - and we - went too far. In pursuit of an image, they helped bring about a reality none of us can bear to look at.