[5] Halliday's grammar differs markedly from traditional accounts that emphasise the classification of individual words (e.g. noun, verb, pronoun, preposition) in formal, written sentences in a restricted number of "valued" varieties of English.
Halliday's model conceives grammar explicitly as how meanings are coded into wordings, in both spoken and written modes in all varieties and registers of a language.
[7][8] Halliday's seminal Introduction to Functional Grammar (first edition, 1985) spawned a new research discipline and related pedagogical approaches.
By far the most progress has been made in English, but the international growth of communities of SFL scholars has led to the adaptation of Halliday's advances to some other languages.
His parents nurtured his fascination for language: his mother, Winifred, had studied French, and his father, Wilfred, was a dialectologist, a dialect poet, and an English teacher with a love for grammar and Elizabethan drama.
In 1972–73 he was a fellow at the Center for Advanced Study in the Behavioural Sciences, Stanford, and in 1973–74 professor of linguistics at the University of Illinois.
In 1974 he briefly moved back to Britain to be a professor of language and linguistics at Essex University.
[20][21] Halliday's grammatical theory and descriptions gained wide recognition after the publication of the first edition of his book An Introduction to Functional Grammar in 1985.
Halliday's conception of grammar – or "lexicogrammar", a term he coined to argue that lexis and grammar are part of the same phenomenon – is based on a more general theory of language as a social semiotic resource, or "meaning potential" (see Systemic functional linguistics).
[22] He argues that "theoretical categories, and their inter-relations, construe an abstract model of language ... they are interlocking and mutually defining.
[23] So the theory "is continually evolving as it is brought to bear on solving problems of a research or practical nature".
These categories are "of the highest order of abstraction", but he defended them as necessary to "make possible a coherent account of what grammar is and of its place in language"[26] In articulating unit, Halliday proposed the notion of a rank scale.
The units of grammar form a hierarchy, a scale from largest to smallest, which he proposed as a sentence, clause, group/phrase, word, and morpheme.
[27] Halliday defined structure as "likeness between events in successivity" and as "an arrangement of elements ordered in places".
Halliday explains this preoccupation in the following way: "It seemed to me that explanations of linguistic phenomena needed to be sought in relationships among systems rather than among structures – in what I once called "deep paradigms" – since these were essentially where speakers made their choices".
Because it stands as a metaphor for society, language has the property of not only transmitting the social order but also maintaining and potentially modifying it.
(This is undoubtedly the explanation of the violent attitudes that under certain social conditions come to be held by one group towards the speech of others.
According to Halliday, as the child moves into the mother tongue, these functions give way to the generalised "metafunctions" of language.