structural:summarization, quality:correction, quality:corruption
Humanistic theory

The humanistic tradition considers language as a human invention. Renaissance philosopher Antoine Arnauld gave a detailed description of his idea of the origin of language in Port-Royal Grammar. According to Arnauld, people are social and rational by nature, and this urged them to create language as a means to communicate their ideas to others. Language construction would have occurred through a slow and gradual process. In later theory, especially in functional linguistics, the primacy of communication is emphasised over psychological needs.

The exact way language evolved is however not considered as vital to the study of languages. Structural linguist Ferdinand de Saussure abandoned evolutionary linguistics after having come to the firm conclusion that it would not be able to provide any further revolutionary insight after the completion of the major works in historical linguistics by the end of the 19th century. Saussure was particularly sceptical of the attempts of August Schleicher and other Darwinian linguists to access prehistorical languages through series of reconstructions of proto-languages.

Saussure's solution to the problem of language evolution involves dividing theoretical linguistics in two. Evolutionary and historical linguistics are renamed as diachronic linguistics. It is the study of language change, but it has only limited explanatory power due to the inadequacy of all of the reliable research material that could ever be made available. Synchronic linguistics, in contrast, aims to widen scientists' understanding of language through a study of a given contemporary or historical language stage as a system in its own right.

Although Saussure put much focus on diachronic linguistics, later structuralists who equated structuralism with the synchronic analysis were sometimes criticised of ahistoricism. According to structural anthropologist Claude Lévi-Strauss, language and meaning—in opposition to "knowledge, which develops slowly and progressively"—must have appeared in an instant.

Structuralism, as first introduced to sociology by Émile Durkheim, is nonetheless a type of humanistic evolutionary theory which explains diversification as necessitated by growing complexity. There was a shift of focus to functional explanation after Saussure's death. Functional structuralists including the Prague Circle linguists and André Martinet explained the growth and maintenance of structures as being necessitated by their functions. For example, novel technologies make it necessary for people to invent new words, but these may lose their function and be forgotten as the technologies are eventually replaced by more modern ones.