Even the best of us can get lost in our metafictive regressions. Julian Gough, writing on Cif on Monday was so keen to have a pop at modern writers - Ian McEwan in particular - for having no ideas big enough to carry a novel, that he forgot to make sure that his own ideas could sustain his argument.

Now I'm no big fan of Ian McEwan. I find his prose forensic and cold, his characters uninvolving and his last two books have been easily his worst; Saturday was unbearably twee, with a story that bordered on the facile, and On Chesil Beach featured a dull couple and a plot twist that was totally unbelievable. But to argue that McEwan's key themes are so thin they can only sustain a short story is just nonsense.

OK, so no one's ever going to claim that Saturday or On Chesil Beach are works of any great gravitas. But how strong does an idea have to be to be worthy of novel-length fiction? If one works from Gough's thesis, then virtually every book ever written would have been better off as a short story.

For McEwan is far from the worst offender when it comes to thin ideas. Nick Hornby has made a career out of the male mid-life crisis; 9/11 has spawned any number of dull books about being Americans and Muslims coming to terms with a new world order; and Philip Roth's highly acclaimed Everyman revolved entirely around the notion that getting old is a bit of a bummer.

And it's not just modern authors that fall short on ideas. Heresy, I know, but didn't Jane Austen, to all intents and purposes, hang the same love story round the same wry comedy of class and manners? Trollope's Barchester Chronicles? A series of tales about a bunch of conniving, grasping clergy. Ernest Hemingway? The complete guide to being macho.

Reducing any book to a single, central idea is almost bound to make it look a bit obvious and dull. But to focus on ideas alone is to miss the point. For while you might prefer a book to be about something worthwhile - and believe me there are plenty that have a total absence of depth - it's not the idea that makes or breaks the story. It's the writing and the characterisation that carries the reader and this is why writers, such as Austen, still remain so popular. She allows her characters to come alive in a way we care about and any underlying social commentary is just a natural part of her storytelling.

It's not just simplistic to suggest that novels need big ideas. Gough claims his raison d'etre is to rescue the short story from the scourge of market forces driving writers towards the novel. But the only sensible conclusion you can draw from his argument is that the short story is always going to be second best - a fallback for writers with no ideas worthy of a novel.