Grammatical knowledge: a structured inventory of symbolic units
As we noted earlier, a central claim in some cognitive approaches to grammar is that knowledge of language (the mental grammar) is represented in the mind of the speaker as an inventory of symbolic units (Langacker 1987: 73). It is only once an expression has been used sufficiently frequently and has become entrenched (acquiring the status of a habit or a cognitive routine) that it becomes a unit. From this perspective, a unit is a symbolic entity that is not built compositionally by the language system but is stored and accessed as a whole. Furthermore, the symbolic units represented in the speaker’s grammar are conventional. The conventionality of a linguistic unit relates to the idea that linguistic expressions become part of the grammar of a language by virtue of being shared among members of a speech community. Thus conventionality is a matter of degree: an expression like cat is more conventional (shared by more members of the English-speaking community) than an expression like infarct, which is shared only by a subset of English speakers with specialist knowledge relating to the domain of medicine (this expression refers to a portion of tissue that has died due to sudden loss of blood supply). The role of entrenchment and conventionality in this model of grammar emerge from the usage-based thesis.
Symbolic units can be simplex or complex in terms of their symbolic structure. For example, a simplex symbolic unit like a morpheme may have a complex semantic or phonological structure, but is simplex in terms of symbolic structure if it does not contain smaller symbolic units as subparts. The word cat and the plural marker -s are examples of simplex symbolic units. Complex units vary according to the level of complexity, from words (for example, cats) and phrases (for example, Lily’s black cat) to whole sentences (for example, George kicked the cat).
The contents of this inventory are not stored in a random way. The inventory is structured, and this structure lies in the relationships that hold between the units. For example, some units form subparts of other units which in turn form subparts of other units (for example, morphemes make up words and words make up phrases which in turn make up sentences). This set of interlinking and overlapping relationships is conceived as a network. There are three kinds of relation that hold between members of the network: (1) symbolisation (the symbolic links between semantic pole and phonological pole that we described earlier); (2) categorisation (for example, the link between the expressions rose and flower, given that ROSE is a member of the category FLOWER; and (3) integration (the relation between parts of a complex symbolic structure like flower-s).
As a constraint on the model – in other words, a statement that places limits on how the model operates – Langacker (1987: 53–4) posits the content requirement. This requirement holds that the only units permissible within the grammar of a language (‘grammar’ in the sense of ‘model’) are (1) phono logical, semantic and symbolic units; (2) the relations that hold between them (described above); and (3) schemas that represent these units. This requirement excludes abstract rules from the model. Instead, knowledge of linguistic patterns is conceived in terms of schemas. We return to this idea below (section 14.4.3).
