In approaches of modern linguistics, what is the difference between the Structuralist and Mentalist approaches to linguistics and language?
Founded by Saussure, the structural approach to linguistics arose as the first linguistic challenge to diachronic linguists, which studies the development and change of language systems over time, for example the changes and linguistic routes that led from Chaucer's Middle English to Shakespeare's Renaissance English. Saussure advocated studying language at the present moment in time--or even at any given moment in time--and analyzing the relationships between the component parts of the language system. These component parts he classified as langua while the conversation upheld by the langua he called parole. Structuralism is focused on langua, which is to say structuralism is focused on the relationships between component parts of expressions of language.
Chomsky is most closely related to the mentalist approach to linguistics, which is also the cognitive approach. Mentalism arose as a reaction against structuralism and, more emphatically, against the behaviorist approach to linguistics and language acquisition through which both are reduced, in brief, to patterned, environmentally learned processes. Mentalists stress an innate mechanism for language acquisition, which is an assertion they support in part with data from all over the world in which children of all cultures and of all language traditions follow the same patterns and time frames for linguistic and language learning processes. Mentalists depart from structuralists by examining the cognitive processes associated with both langua and parole whereas structuralists limit themselves to examining langua and the relationships within expressions of langua.