Linguistic Categorization 2nd Ed.

Categorization is fundamental to all higher cognitive activity. Yet the seeing of sameness in difference raises deep philosophical problems. One extreme position, that  of nominalism, claims that sameness is merely a matter of linguistic convention; the range of entities which may be called dogs, or the set of colours that may be described as red, have in reality nothing in common but their name. An equally extreme position is that of realism. Realism claims that categories like DOG and RED exist independently of language and its users, and that the words dog and red merely name these pre-existing categories.