Has the internet killed the Great American Novel?

When someone like Johnny Depp says American culture is a disaster, you take it with a pinch of salt. After all, it's not as if Pirates of the Caribbean is the apogee of film-making, even though the adventures of Captain Jack Sparrow are among the highest-grossing movies yet. But it seems Depp's is not the only voice of dissent. Recently, the critic Lee Siegel, writing in the New York Observer, declared American fiction "culturally irrelevant". On Tuesday, the prestigious London bookshop Foyles will hold an event with the headline-grabbing title, "Is America Over?" Leaving aside the rather amusing notion of an entire country being treated as if it were a fly-by-night cultural trend, the concerns are real. And Siegel's piece has caused a veritable storm.

Its headline - "Where have all the Mailers gone?" - speared the heart of the problem. By that Siegel really meant: "Where has the Great American Novel gone?" Norman Mailer truly believed in this concept; a perfect work of fiction that could somehow meld the private lives of its characters with broad "state of America" themes. The bigger the book, the better, too. And since the 1960s, the Great American Novel has become the mighty beast that stalks any new American novelist with pretensions to being filed under literary fiction. It hasn't helped that America has, until recently, enjoyed something of a purple patch in the genre, thanks to John Updike, Kurt Vonnegut, Thomas Pynchon, Philip Roth and Don DeLillo. The problem is, most of these literary giants have either died or begun to lose their powers. And there's no one, according to Siegel, to take their place. Moreover, he argued, "the most interesting, perceptive and provocative writers of our moment write narrative non-fiction".

Has Siegel got a point? Will Richard Russo, the Pulitzer Prize-winning novelist who is the main draw at Foyles, side with the notion of "the fall of the 21st-century Babylon"? Certainly any previous fascination with American literature was representative of the broader dominance of American culture. But the dismay caused by the George W Bush years, combined with the incessant globalisation that sees the country's brands in every shopping mall across the world, may have dulled the allure of the American Dream. And if the rest of the planet feels strangely ambivalent about America, it perhaps follows that American novelists themselves will also be unsure about how to define their culture.

It's not that American writers aren't still keen to write about big themes. This year, Dave Eggers took on one of the greatest natural, economic and social disasters in America's history with his Hurricane Katrina book Zeitoun, but it was just the kind of narrative non-fiction that Siegel believes is now the dominant force in the country's writing. Adam Haslett's debut novel, Union Atlantic, takes on the excesses of the banking system. It is a fascinating and at times enthralling book. But at just 300 pages, it's not the epic Siegel and many others clearly miss.

Perhaps that's why there's so much such excitement around the September publication of Jonathan Franzen's first novel in nine years. His book The Corrections, published in 2001, is regularly cited as one of this century's most important books. The story of a dysfunctional American family, it seemed to nail America at a time of great change. His new work, Freedom, appears to cover similar ground, but it'll be interesting to see how he deals with a world that has changed so much in the interval between the books.

It's a change that Philip Roth, for one, blames on the internet. He was probably having a bit of fun when he predicted that in 25 years, attention spans will have shrunk so much the audience for novels will have dwindled to those for Latin poetry today. But there was an interesting subtext to his comments. Perhaps this snappy, hyper-connected, fast-paced world is shaping the kind of literature we get.

The notion of fine-tuning a doorstop epic about America over a period of years is probably alien to the young writers who featured on The New Yorker's "20 under 40" list of young novelists: the initial subject of Siegel's ire. Chimamanda Ngozi Adichie and Jonathan Safran Foer - to name two on that list - are different kinds of writers from those Americans may have been used to hailing in the past. But in writing perceptively about the world as a whole, they prove America isn't over. It's just different, and, whisper it, perhaps just a little less self-obsessed.