Roots, stems and word classes
The assignment of a linguistic sign to a word class is an operation that must be seen as part of the overall transformation of extralinguistic substance into linguistic form. In this, it is comparable to such processes as the transitivization of a verbal base, which further specifies a relatively rough categorization. Languages differ both in the extent to which they structure the material by purely grammatical criteria and in the level at which they do this. The root and the stem are the lowest levels at which a linguistic sign can be categorized in terms of language-specific structure. Further categorization is then achieved at the level of the syntagm.
An empirical investigation comparing the categorization of roots and stems in a sample of six languages (English, German, Latin, Spanish, Yucatec Maya, Mandarin Chinese) turns up far-reaching differences. These differences in the amount of categorization that languages apply to linguistic signs at the most basic levels throw into doubt any thesis claiming universal categoriality or acategoriality for roots. Such a static view must be replaced by a dynamic one which asks for the role of categorization in linguistic activity. At the same time, these differences raise the issue of the amount of structure — or of grammar — that is necessary for a human language.1