Halliday & Matthiessen (1999: 89, 90):
Within the lexical zone, we have already referred to the differentiation according to the degrees in delicacy; in particular, the 'basic' degree of delicacy stood out as most highly elaborated. There are also grammatical reactances indicating the taxonomic differentiation between the "basic" degree of delicacy and lower degrees of delicacy, at least in cases where the taxonomic relationship is of a particular kind. For example, the less delicate category may be construed by a mass noun whereas the more delicate, basic degree categories may be construed as count nouns: see Table 2(8).Wierzbicka (1985: 321-2) identifies this phenomenon and shows that it is not arbitrary. Her explanation is in fact that the relationship between e.g. 'furniture' and 'chair, table' as super-category and subcategory is not the normal 'kind of relationship between e.g. 'bird' and 'swallow, magpie', but rather a grouping of different kinds according to similarity in use:Thus, supercategones such as bird or tree are 'taxonomic', i.e. they belong to hierarchies of kinds (where each 'kind' is identified on the basis of similarity between its members); supercategories such as crockery, cutlery or kitchenware are not taxonomic — they include things of different kinds, grouped on the basis of contiguity and/ or similarity of function, not on the basis of similarity of form.We take delicacy to include both types of the relationship of supercategory to subcategory — both the "taxonomic" and the "non-taxonomic" ones. However, it would seem that with the relationship between 'furniture' and 'chair', 'table' &c. we are on the borderline between elaboration and extension.
