Geometric metaphors and linguistic genealogy

In placing the study of linguistic change as one of their central interests, the nineteenth-century linguists mostly addressed the question of the difference between languages from a historical perspective, feeding nationalist ideals and was attentive to identifying elements and particulars of the differentiation between languages. In opposition to this viewpoint, some models with a different orientation were proposed. For example, the philosophy of mixture proposed by William Dwight Whitney was an original attempt to overturn the dominant linguistic perspective, as it levered on elements of sharing and mixing among populations and languages rather than on differentiation. It was probably inspired by continuist models that started to appear, with prudence, in the scientific debate of the different models for representing the genealogy of languages ([1]; cf. [2]). At the same time, research about universal traits in the relationships of similarity and difference among languages led to models that existed in nature: natural forms and types could be adapted to assimilating languages and their mutations over time. These images worked long in the history of linguistics, some of them are still very well-known and alive, others less so. Of these two, the first has given impetus to the genealogical representation of languages through the image of the tree trunk from which branches, twigs, and leaves split off; the other, more problematic image, imagines the life of languages as the rippled surface of a pond, in this way, yielding a decidedly more complex and realistic vision of mutations.