As the name suggests, the notion of
system is a defining aspect of systemic functional linguistics. In linguistics, the term "system" can be traced back to
Ferdinand de Saussure, who noticed the roughly corresponding paradigms between signifying forms and signified values. The paradigmatic principle of organization was established in semiotics by Saussure, whose concept of value (viz. "valeur") and of signs as terms in a system "showed up paradigmatic organization as the most abstract dimension of meaning". In their case,
system does not stand for a list of signifying forms corresponding to a list of signified values. Instead, Firth and Halliday described systems as contrasting options in value realised by contrasting options in form where the options are not the entire form and the entire value but features thereof. In this sense, linguistic systems are a background for formal features, i.e. features of structure. Here, the most general linguistic system is human adult language itself since it is a system of options whereby humans choose whether to speak
in English,
in Chinese,
in Spanish or in another variety of language. In this sense, language is a system ("the system of language") not only as proposed by
Hjelmslev., but also as a system of options. In this context,
Jay Lemke describes human language as an open, dynamic system, which evolves together with the human species. In this use of
system, grammatical or other features of language are best understood when described as sets of options. According to Halliday, "The most abstract categories of the grammatical description are the systems together with their options (systemic features). A systemic grammar differs from other functional grammars (and from all
formal grammars) in that it is paradigmatic: a system is a paradigmatic set of alternative features, of which one must be chosen if the entry condition is satisfied."
System was a feature of Halliday's early theoretical work on language. He considered it one of four fundamental categories for the theory of grammar—the others being
unit,
structure, and
class. The category of
system was invoked to account for "the occurrence of one rather than another from among a number of like events". At that time, Halliday defined grammar as "that level of linguistic form at which operate closed systems". In adopting a system perspective on language, systemic functional linguistics have been part of a more general 20th- and 21st-century reaction against atomistic approaches to science, in which an essence is sought within smaller and smaller components of the phenomenon under study. In
systems thinking, any delineated object of study is defined by its relations to other units postulated by the theory. In systemic functional linguistics, this has been described as the
trinocular perspective. Thus a descriptive category must be defended from three perspectives: from above ("what does it construe?" "what effect does it have in a context of use?"), below ("how is this function realised?") and round about ("what else is in the neighbourhood?" "what other things does this thing have to interact with?"). This gives systemic functional linguistics an affinity with studies of
complex systems. ==System network in systemic linguistics==