This year’s Man Booker Prize shortlist has opened a debate on the length of novels, with the chair of the judges the philosopher Kwame Anthony Appiah suggesting that some of the submissions for the £50,000 prize “needed more editing”.

The six titles (and their UK publishers) are Anna Burns’ Milkman (Faber), Esi Edugyan’s Washington Black (Serpent’s Tail), Daisy Johnson’s Everything Under (Jonathan Cape), Rachel Kushner’s The Mars Room (Jonathan Cape), Richard Powers’ The Overstory (William Heinemann) and Robin Robertson’s The Long Take (Picador).

At 500 pages Powers’ The Overstory has been described as a “majestic redwood” of a novel.  The judges clearly felt that in its case, every page earned its place.  But speaking more widely about general submissions Appiah said: “We occasionally felt that inside the book we read was a better one, sometimes a thinner one, wildly signalling to be let out.  We’re all writers as well as readers and we all value the work of editors.  There were times when we felt this editorial role could have been, shall we say, more energetically performed.”

He added: “This is not a complaint against the very idea of the long immersive read.  One of the books on our shortlist is very long indeed [Richard Powers’ The Overstory] and we thought it earned its length… but the chastening pencil has its role and subtraction can be as potent as addition.”

His fellow judge, the crime novelist Val McDermid wondered whether “young editors coming through are not necessarily getting the kind of training and experience-building apprenticeship that happened when I was starting out, for example”.  The other judges this year were the cultural critic Leo Robson, the feminist writer and critic Jacqueline Rose; and the artist and graphic novelist Leanne Shapton.

The debate led to an editorial in the Guardian which noted the phenomenon of ‘book inflation’.  ‘The last part of Karl Ove Knausgard’s My Struggle runs to almost 1200 pages, and Paul Auster’s most recent novel 4321 is almost as long as his previous three books put together,’ the paper said.  ‘[Those who approve] may credit increased boldness and mastery of material.  The unimpressed blame growing authorial egos.’

What is excellent for the industry is the increased publicity for books that such debates bring – and the winner of this year’s Man Booker Prize, whatever its length, will be announced on Tuesday, 16 October at London’s Guildhall.