How would you choose the year's best books?

Last year's Man Booker Prize Long List represented five continents and seven countries, with authors from Australia, Canada, Malaysia, New Zealand and Zimbabwe, alongside three from Ireland and five from Britain.

This year, for the first time, the prize has been opened to writers from the USA. Oddly, the widening of its geographical scope seems to have coincided with a narrowing of its cultural reach. On the current long list a single Australian novel represents the Commonwealth, with two from Ireland, six from Britain and four from the US. In subject matter as well as authorship, the chosen novels seem to be overwhelmingly rooted in Western experience. And there's a marked gender imbalance – only three female writers out of thirteen, whereas last year's list was evenly split, with eight women and seven men.

Publishing that 2013 list, the judges, chaired by travel writer and scholar Robert MacFarlane, described it as 'surely the most diverse' in the prize's history, evidently considering that something to brag about. This year's judges have apparently taken a different approach. The chairman, philosopher A.C. Grayling, said, 'Our guiding principal was merit. We didn't ask about the nationality or gender, there was no question of tokenism.' That sounds admirable as a philosophical abstraction. Tokenism is generally objectionable, and what could be wrong with basing your judgements on 'merit'?

But artistic merit is a slippery concept. Three years ago, some of the judges raised eyebrows when they revealed the basis on which they'd made their decisions. That year's chairman, retired spy Stella Rimington, set the tone, saying they'd been 'looking for enjoyable books… readable books.' MP Chris Mullen had been in no doubt from the start that the winner would have to 'zip along'. It seemed not to have occurred to them that a book might make demands on a reader and offer more subtle rewards, or that as judges they had a greater responsibility than someone sounding off at a party about what kind of books they happened to like.

In an article in the Guardian accompanying news of this year's long list, the American writer and critic Erica Wagner indicated a more thoughtful set of criteria. She and her fellow judges had been drawn to 'vivid characters', and impressed by books that would bear re-reading or that stand out for the quality of their language, 'ambitious' books that deal with large questions, about 'the making of art', or about 'what it means, finally, to be human'.

These judges had clearly applied their minds seriously to an informed discussion of what 'best' might mean. And yet I can't help wondering whether, if I were a judge, I would have the confidence in the objectivity of my judgement not to step back and take a look at the overall shape of the list I was helping to construct, not to take note of nationality or gender, and not to wonder if, in favouring writers whose cultural experience happened to be closer to mine, I might be underappreciating less familiar qualities.

Joe Treasure is the author of two novels: “The Male Gaze” and “Besotted”, and teaches creative writing at Royal Holloway, University of London. Read more of him at http://joetreasure.blogspot.co.uk/