While every picture tells a story, look elsewhere for the whole truth

It is a truth universally acknowledged that a film-maker who seeks to represent the past will distort it. Such, at least, is the opinion of many of those who claim proprietary right to the soubriquet historian - professionals, teachers and custodians of the written record of the past.

To those who believe an account of the past can be trusted only when it is presented with a morass of abstract nouns and passive verbs, hedged around with a thicket of footnotes and debated opinions, a film limited to two hours or less, unable to make apparent its sources, yet requiring strong characterisation, unambiguous morality and distinctive narrative drive, is going to misrepresent the complexity that only a book can express.

Yet film-makers wilfully persist in approaching historical subjects, and the public shows an unseemly enthusiasm for encountering the past on screen. Filmic images of the past can be hugely memorable - distressingly so if, as so often, they exaggerate, simplify or present a downright lie. Reluctantly, historians have had to engage with the work of film-makers who want to address the past, but the space for constructive dialogue can be remarkably small.

What term should be applied to such film-makers? Do they qualify for the title of historian? If not, then what?

Robert Rosenstone, a self-proclaimed postmodernist, has little truck with these fusty custodians of the faith. He argues that film and academic history have their own narrative forms, and while each is therefore able to do something the other cannot, neither can claim primacy, or at least purity. As an archival historian whose biography of the journalist John Reed was used as the source material for Warren Beatty's blockbuster Reds, he is well aware that film may be derivative of the work of a historian; yet he disowns any proprietorial claim on the biographical portrait he created, accepting that film's inevitable emphasis on individual agency, heightened emotions and critical encounters, will always make the text-bound historian wriggle uncomfortably in the stalls.

Further, he argues that some film-makers may have such an intelligent, sustained, complex and creative relationship with the past that there is no title that can be applied to them other than historian. Their work is not just parasitic on the research of others, but proves to have something to say about the past that could not have been discovered in any other way.

His prime witness here is Oliver Stone, whose films on 1960s and 1970s America, JFK , Platoon , Born on the Fourth of July and Nixon , among others, engage with the real issues facing America in dealing with the traumas of those years. To Rosenstone, these films represent a sustained and intelligent interrogation of the past, involving both a historian's understanding of the documentary facts and an artist's intuitive feel for the dramatic possibilities.

In some ways, though, his choice of Stone as the paradigmatic historian-on-film is a strange one, for even though JFK , as Rosenstone points out, raises the issue of the extent to which the past is knowable and representable, there is no doubt that this film has given a huge boost to conspiracy theories. Is this a contribution to history or to a media-led feeding frenzy? Rosenstone describes JFK as a work of "modernist or even postmodernist history"; but his analysis of its merits zeros in on the postmodernist side, as he has nothing modernistic or positivistic to say about whether the JFK "take" on the assassination is plausible or just plain wrong.

It is a shame, too, that Rosenstone does not deal at equal length with other film-making historians. I would have liked a more sustained analysis of Steven Spielberg, who can surely claim the honorific of historian, and who has taken much trouble to "get the facts right". Equally, it is a shame that, writing at a time when the televised history documentary is such a burgeoning medium, his chapter on documentaries is rather opaque.

While this book begins as a breath of fresh air, by the conclusion the self-reflexive mode makes one wish that the theme was not just "History on Film/ Film on History" but included Film Historians on History on Film, Film on Film Historians on History, History on Film Historians on Film, and so on.

Peter Furtado is editor of History Today .