In Indo-European languages, the distinction between lexicon and grammar grounds on a certain empirical basis, owing to the importance of morphology, but in SAE languages many units prove to have both lexical and grammatical uses. Therefore the notion of grammaticalization occupies an important place in the descriptions of SEA languages.
I quote here Bisang (2009: 2-3). “In a large number of languages in East and mainland Southeast Asia, grammaticalization is characterized by the following characteristics: lack of obligatory categories and predominance of pragmatic inference (…). The lack of obligatoriness is particularly remarkable in cases where the concept inferred is an abstract grammatical concept that is expressed by obligatory categories in Indo-European languages. While these functions are conventionalized in Indo- European, they are the product of pragmatic inference in many markers of East and mainland Southeast Asian languages.”
An example among many others : trəv in Khmer has a lexical value ‘to hit accidentally’ on the one hand, and a large series of other uses on the other hand : ‘necessity’, ‘conformity’, ‘detrimental value’, ‘passive’ (Paillard & Thach, 2009). An analysis grounding on grammaticalization implies splitting up the word.
Taking « grammatical » as equivalent to obligatory leads to considering the SEA languages as working without a real grammar. As a matter of fact, the current grammars, which ground on the terminology and the categories of the occidental grammars, give a distorted conception of the properties and of the structure of those languages. Some of the main data are not even taken into account.
Working out grammars accounting for the specificity of those languages is a major challenge, not only regarding a linguistic description, but also the practice of those languages, including that of the media as well as the way they are taught, and consequently the training of the teachers. In Cambodia to-day, working out an extensive Khmer grammar, in Khmer, for the Khmers is a great objective to be aimed in order to support and illustrate the Khmer language.
BISANG, W. (2009), Grammaticalization and the areal factor in East and mainland Southeast Asian languages. http://www.linguistik.uni-mainz.de/bisang/publications/.
PAILLARD D. & THACH D. (2009) A propos de trəv en khmer contemporain, Cahiers de linguistique d’Asie orientale, 38, 1, pp. 71 – 124.