(Writing Systems, An introduction to their linguistic analysis, Florian Coulmas)
Although there is plenty of evidence that, literate cultures, writing intrudes into linguistic behaviour of people and that without writing many languages would not be what they are, the notion that writing is an active agent of language is unpalatable to many linguists for a number of reasons. One is that in modern linguistic languages are stripped of their historical dimension. Although the obvious fact that language change in the course of time is acknowledged, the possibility that their nature may be affected by external factors such as writing is strictly denied, allegedly on the grounds that writing could not possibly have exercised any influence on the faculty of language because it is too recent an invention. The oldest records reach back a bit more than ten thousand years at best, while language must have evolved hundreds of thousands of years ago. Diachronic linguistics is essentially unhistorical, because, as a defining capacity of the human race, language is not supposed to change by virtue of humanly contrived technology. There are no highly or less highly developed languages. This is a primitive of linguistics. Artifacts and technologies, such as writing, for example, are granted the potential to change the environment, but not humanity itself. Since language is conceived as an essential part of human nature, while writing is a mere technology, the effects of writing on language and by implication the complexities of their interrelationship remain largely unexplored.
Scholars in the language sciences who do believe that the invention or discovery of writing does make a difference, both with respect to what language is and how we think about it, are in a minority. Linguistic orthodoxy happily concurs with Ferdinand de Saussure's apodictic statement that made Aristotelian surrogationalism a cornerstone of modern linguistics:
"Language and writing are two distinct system of signs; the second exists for the sole purpose of representing the first. The linguistic object is not both the written and the spoken forms of words; the spoken forms alone constitute the object." (Saussure 1959:23)
Saussure, Ferdinand de. 1959. Course in General Linguistics. Translated by Wade Baskin. New York: The Philosophical Library.
Since the majority of languages of the world are unwritten, it is only prudent to ignore writing when studying language. However, this argument is not as sound as it seems. For, if all languages are of kind it follows that if some language are writable all languages are, and since writing is undeniably not the same as language, it is a legitimate question how the two relate to each other. Two questions linguistics should not sidestep are: 'what happens when a language is written down, (1) in terms of linguistic description, and (2) in terms of linguistic evolution?' As a matter of fact, linguistic never study any language without recording speech and writing it down. This alone is a compelling reason for studying writing instead of assuming that writing, whose essential properties are so radically different from speech, can be ignored in the research process.
Since Saussure, grammatical theory has undergone revolutionary changes, but the central concept of relating sound to meaning in a structured way has remained the same. Saussure's model of the linguistic sign still captures the main point. Sound in language has three aspects, which he distinguishes: physical (sound waves), physiological (audition and phonation) and psychological, that is, sounds as abstract units, which he calls 'sound images' (images acoustiques).
"The linguistic sign unites a concept and a sound image. The latter is not the material sound, a purely physical thing, but the psychological imprint of the sound, the impression that it makes on our senses." (Saussure 1956:66)
"Our conception of language is deeply influenced by a long tradition of analyzing only written language, and that modern linguistic theory, including psycholinguistics and sociolinguistics, approaches the structure and mechanism of spoken language with a conceptual apparatus, which - upon closer scrutiny - turns out to be more apt for written language in surprisingly many fundamental aspects" (Linell 1982: 1).
Linell, Per. 1982. The writing Language Bias in Linguistics. Linköping: Linköping University, Department of Communication Studies.
(...) Faber (1992: 110) interprets the observation that many speakers cannot divide words into phonological segments 'unless they have received explicit instruction in such segmentation comparable to that involved in teaching an alphabetic writing system' as evidence that historical segmentation ability was a consequence of alphabetic writing, not a prerequisite. Various sounds such as diphthongs and prenasalized consonants, which in alphabetic writing are represented by sequences of letters, cannot realistically be conceived as isolated steady units.
(...) David Olson (1994) stresses the point that the concept of the word as distinct unit is a by-product of literacy acquisition. Morphology, the study of words and their parts, is deeply imbued with notions of literate 'word processing', such as 'lexical entry', for example. 'Lexicon' itself is such a term. A lexicon is a list of isolated words, a kind of usage that does not occur naturally in speech. The word is an artificial entity in another sense as well. It is basically the kind of unit that is listed in a dictionary and thus not necessarily the same in all languages.
Olson, David. 1994. The World on Paper. Cambridge: Cambridge University Press.
Static entities like the stock of words, sentences and written texts are alien to the spoken language where meaning is constituted in the act of speaking, bound to situation, speaker, context, the interaction history of speaker and listener, and so on. (...) As Olson demonstrates at length, this terminology is not fortuitous but speaks of the fact that linguistics is grounded in written language. Since linguistics is concerned with 'natural language' while writing is an artifact, this is difficult to openly integrate into linguistic theory, which, as a result, is characterized by scriptism, which has been defined as "the tendency of linguists to base their analyses on writing-induced concepts such as phoneme, word, literal meaning and sentence, while at the same time subscribing to the principle of the primacy of speech for linguistic inquiry." (Coulmas 1996:455)
As Olson sees it, linguists are in this respect representative of literate society at large where writing provides the model for speech, rather than the other way around. We pronounce as we spell, we judge our utterances against the yardstick of written sentences and qualify as ellipsis, anacoluthia, reduction, false start and so on those which do not conform to these patters. The literal meaning of a sentence is basic. Other meanings are taken to be derived from it. To a scholar who, like Olson, looks at language as something to be learned, such a conception, perhaps, comes quite naturally because it is the written form of language that is made the object of instruction, memorization and testing. As an institution, the school instils into the collective mind the primacy of writing. In contrast, those who prefer to look at language as a natural capacity tend to insist on the primacy of speech. These seemingly irreconcilable positions reflect the two sides of language, the acquired and the innate. Since on human being exists as purely natural creature, both can be dissociated only in theory. This is the deeper meaning of Olson's notion that writing is a model of speech.