Two women photographers opened shows in London last week, both with considered and unsettling views of human affairs. Susan Lipper is a New Yorker who for five years has repeatedly revisited the small community of Grapevine Hollow in West Virginia, and her prints, which she calls 'a journal', are at the Photographers' Gallery. Candida Hofer has a high reputation in her native Germany, but the exhibition at Anderson O'Day is her first in this country.

Its theme is British. She offers views of various institutions, particularly libraries, museums and universities. Evidently enough, Lipper belongs to the American tradition of 'social landscape', with antecedents in the work of Walker Evans and Robert Frank, photographers whose mission was primarily descriptive and who were inspired by the vastness of America and the circumscribed or lonely lives of poor people who made a living from the land. Her work is individual, but surely owes much to the pioneers of such documentary camerawork. Hofer has a more overtly aesthetic approach, but it's aestheticism of a special kind. These photographs of public places belong to a sub-branch of conceptual art, the examination and criticism of museums that was so popular in the early Seventies, when Hofer began her career.

For this reason she seems slightly dated. Lipper's photographs, on the other hand, have what we might call a depth of datedness. In the first place their attitude belongs to an old humanistic tradition. Secondly, their style evokes the late Sixties as much as the Nineties. And thirdly, they record an American tragedy, one rooted in the days when the Appalachian mountains, where Grapevine Hollow is to be found, formed the frontier between America's sophisticated east and unsettled west. Whatever the poverty in Evans's and Frank's photographs, they spoke of a new nation, one that might grow. In Lipper's interpretation, Grapevine Hollow is a symptom of a country that is dying.

Lipper's Sixties style evokes not just the look of photography of that decade but also the political will of the time. It was the period of Lyndon Johnson's 'Great Society', when that mysterious President, with the aid of a Democrat-dominated Congress, announced plans for the elimination of poverty. The problems of Appalachia led to a special development Act. Lipper's prints say nothing about the political background. Neither does the book that goes with the exhibition (Cornerhouse Publications) but we cannot doubt that her work has a social dimension. She has travelled to Grapevine Hollow to see how industrial decline and social neglect have affected an American village; and the results are as bleak, as terminally depressed, as war photography.

Lipper has learnt from photographers who cover wars, but differs from them in one essential way. War photographers do not exaggerate: battlefields have no need of added drama. Neither does Lipper use exaggeration, but that is because she wishes that peaceful life might emerge from Grapevine's squalor and violence. She retreats a little from her subjects, the men with guns, the smashed cars, pointless fires in the woods, the way that Grapevine people, even or perhaps especially in their good moods, seem to grapple with each other or with their children. Lipper's eye sees what Grapevine life is like, but she does not herself grapple, and the camera keeps its distance.

The first shot of Grapevine tells you to keep away. A slaughtered deer has been hung by its neck from a basketball goal, an innocent animal (it looks like a young doe) on a sporting gibbet. In every further print there is a sense that the outsider should tread warily. It's not exactly fear that we find in the photographs, more a feeling that human relations are fragile and that murder might be the outcome of any kind of transaction. At the back of the book are snatches of conversation that Lipper recorded from the mouths of the people with whom she stayed. Dirt, racial hatred, inter-family feuds, mad Pentecostalist religion, snatched sex, drink, fights at the card table, the possibility of earning a few bucks at a sawmill: these matters, we learn, form the horizons of Grapevine life.

At the same time you can tell from the photos how beautiful the woods and valleys are. As elsewhere in Virginia, the riches that came from coal-mining and logging were found in verdant surroundings. Now that industry has declined and disappeared there are just these poor people, unemployed, without prospects and living in huts and trailer homes. Detritus amid natural beauty is a theme of Lipper's photography. She doesn't overstate the contrasts, just lets you know what's there down in the hollow, and very gently suggests that there are historical reasons for the waste. A sense of history is conspicuously absent from Candida Hofer's photographs. Nor does she allow any sight of a human being to disturb her carefully arranged interiors. This is conceptual photography, whose purpose is to erase traditional culture in favour of a super-knowing use of the lens. Therefore her most telling subjects are in art galleries. Perhaps the best of her prints is of the Victoria and Albert Museum, photographed in such a way as to render its functions blank and inconsequential. She performs similar operations on the Royal Institute of British Architects, King's College London, the British Museum and the Natural History Museum. Art and knowledge is somehow bleached out of these generally blameless institutions. It's all cleverly and coolly done, but the tone of these photographs is almost entirely negative, like so much conceptual art.