I worry about consistency. Yes, I know, it’s what you’d expect an editor to do. But I worry about it in a different sense, too. I worry about the fact that I worry about it.

In my first publishing job, I had a petty tyrant as my production controller. Every transfer stage of the publishing process was a battle between me wanting to make changes and him not wanting to spend any money on the book. With the first set of proofs I gave him, he handed me a sheet of paper to sign which asked me to consider whether the changes I had marked on the proofs belonged to category A, B or C. Category A changes he would reluctantly concede: these were corrections of indisputable errors – of spelling, fact, even grammar. Category C changes, reworkings that dramatically improved on the original, he would allow only once in a blue moon or if there were no other changes at all. Category B changes were changes that re-introduced consistency into the proofs by, for example, changing the system of capitalisation in a heading, or punctuating bullets in line with other lists.

I remember wanting to include a series of commas on one page, to bring it in line with the text elsewhere. My production controller was adamant that these represented a frivolous waste of company money. His final line was ‘I will put these commas in if you can prove that you will sell one more copy of this book with them in than you would without them.’

And, of course, I couldn’t. And maybe he was right: consistency at proofreading stage is a bit of a luxury.

But was he right to imply that nobody pays a blind bit of notice to consistency? That it’s an editorial, maybe a design, affectation, an attempt to justify a basically rather mundane skill?

Here’s why I worry about consistency. I worry that we are more worried about it than anyone else is; that we imagine it represents some significant oofle-dusting that sets our activity apart from others’; that our worry about it comes across as either endearingly or irritatingly quaint to the writers we work with; that people think we must have too much time on our hands, or that we have set our sights dangerously low, if we really think it makes a difference to readers that we spell the same word with an initial capital in one sentence and in lower case in the next. Haven’t we got something better to do?

When you become an editor, there are a number of givens that are so taken for granted that nobody ever bothers to give a reason for them. Starting sentences or paragraphs with digits is one: everyone knows that it’s an editorial crime, but you’ll look in vain in most house styles and in the great copy-editing manuals for any sense of why you shouldn’t do it. And consistency is another: everyone knows it is what we aspire to as editors, but does anyone know why? And, if they do, has anyone got any evidence to support their position?

There doesn’t seem to be any hard-and-fast evidence to show that inconsistency makes reading slower and more difficult (though I remember, dimly, hearing about a research project on this subject undertaken, appropriately, by the University of Reading) – so I will try to justify our obsession with consistency in the absence of any scientific proof.

Consistency is tied up with expectation. It shows people where they are and what they can expect. Parents of young children, poring over parenting manuals at every available opportunity, will vouch for the fact that all of these stress the importance of consistent parental behaviour in giving young children a sense of boundaries. (A very recent piece of research indicates that if you do not impose consistent bed routines on your children you will be damaging their intellectual development – parents can’t win these days.) In the same way, when I was training to be a teacher, I was told how important it was to be consistent in my behaviour with students. Consistency in the classroom was tied up with respect. Students needed to know what they could and couldn’t do, and exactly what penalty awaited them if they moved outside these boundaries. If you were inconsistent in your behaviour, they would take advantage of it and they would lose respect for you – maybe as a way of criticising you for confusing them by not giving them clear signs.

It’s not just parenting and teaching, though: it underpins all our relationships. We are comfortable with people because our experience of them leads us to expect them to react in certain ways, maybe to hold certain views – and we find that knowledge of them reassuring or stimulating. We know where we stand with them. When someone says of another person ‘That’s not like her at all’ or ‘I don’t know what came over him’, it’s a way of saying they acted out of character, inconsistently with other people’s reading of them. This is, of course, a vital aspect of fiction and all forms of drama.

We expect the law to be consistent, too, of course. If I commit a speeding offence, I should pay the same forfeit as the person who committed the same offence the previous week (or his partner, anyway). When that doesn’t happen, trust in the equity of the legal process breaks down, and the drift towards anarchy or dictatorship or just plain chaos begins. When people talk about a breakdown in law and order, after all, they’re talking about a society that is no longer behaving in accordance with the system of formalised and informal rules, regulations, conventions and patterns of behaviour that characterise a more stable community.

It’s a form of semiosis. If you think of it, our whole orthographic system is an attempt to agree a consistent position on how to present our language, whether in its spelling, its punctuation or its structure. The same is true about actual, physical signs. A standardised signage system allows people to know the difference between a car-parking facility, for example, and a public convenience. It’s the reason, of course, Jock Kinneir and Margaret Calvert were employed to construct a nationally acceptable and consistent approach to road signage.

And, in a way that links to the editing and production process, we have certain consistent approaches to the way in which we communicate. We know from the way in which someone talks to us what kind of message they are communicating: question, statement, excited recount, speculation, etc. The prosody, the intonation are the punctuation system of speech. It’s why so many people (of a certain generation) find high rising terminal (HRT) disconcerting – because the speaker’s tone leads them to expect a question when in fact they are being presented with a statement. It’s also one of the reasons that Tony Blair was so irritating to listen to in the mid-point of his premiership – because he deliberately (or so it seemed) flouted the standard conventions on how we organise and present spoken communication.

I could go on. What appears to be the case is that consistency plays an important role in society – it allows us to predict behaviour, it provides a way of organising our experience, it controls the way in which we relate to each other. It demarcates territory, it identifies character and personality, it establishes the rules of engagement. It’s a form of respect, a social adhesive, a road map. Crucially, it allows us not to be distracted by irregularities but to focus on the message in hand. Inconsistency is a smear on the window of communication: it draws people’s attention away from what is being said to how it is being said.

It’s to do with rules.