In The World’s Writing Systems, Peter Daniels begins the book with the declaration that ‘[h]umankind is defined by language; but civilization is defined by writing’. Of course, as he makes clear later in the book, ‘civilization’ can mean a number of things. However, in terms of writing systems – ‘and this is the sense taken over by literacy scholars’ – he means that civilization ‘is marked by the appearance of writing in a culture’ (p.21).
He defines writing as:

‘A system of more or less permanent marks used to represent an utterance in such a way that it can be recovered more or less exactly without the intervention of the utterer.’

And, after dispensing with the belief held by some that pictograms, like the tablet depicting beer in the previous posting, were the forerunners of writing, he makes explicit that ‘it is necessary for a writing system to represent the sounds of a language’.
Actually, when you think about it, this approach – the phoneticisation of writing – is a brilliant idea. If you work out how many sounds there are in a given language, which is always a finite number, categorise them, and use a symbol to represent them, you can record anything you want for any purpose. Whether this be for what John Searles was suggesting or simply to communicate across time and space, you will have an accurate way of communicating information.
What I’m getting round to is that the purpose for which the writing system was invented determines the way we need to teach it. As Daniels and a host of other experts have made clear: speech is primary; writing is secondary. We all grow up learning to speak and listen without having to attend classes to do it. What we don’t learn naturally is reading and writing. These need to be taught and taught explicitly. So now the question is: how?
I’ll be taking up this and other questions in the next few days.