In 1975, M.A.K.Halliday published his account of the ontogenesis of language, Learning how to mean: Explorations in the development of language, the very title of which signalled a radically different orientation from the prevailing one of language as a set of syntactic structures ÃÂ¿acquiredÃÂ¿ between the ages of two and four years. By regarding language as meaningful behaviour, rather than autonomous form, Halliday was led to look for its origins in the infantÃÂ¿s initial attempts at exchanging meanings with caregivers in the very first year of life. His naturalistic case study of the symbolic behaviour of his son, Nigel, from the age of 9 months to 2 years is significant, however, not only because it demonstrates the rich communicative life of human infants, but because Halliday integrated the account of development into his general theory of language, showing the significance of developmental data for explaining the (meta) functional basis of language and the symbiotic relation between language and social system. (See also Halliday 1978a, 1980, 1984)
In this chapter we will draw on the major systemic-functional case studies mentioned above to present an outline of language development in these terms: as a process enabling a gradual progression to generalisation, through to abstraction and finally to (grammatical) metaphor.