Polygrammaticalization of the verb "xāstan" in Persian LanguageA cognitive study in the framework of basic event schemas

Polygrammaticalization is a type of multiple development where a single form develops distinct grammatical functions in different constructions. The verb ‘xāstan’ is an instance of this phenomenon which conceptualizes specific notions of tense, aspect and modality in modern Persian. Xāstan, as a lexical verb and with the meaning “to want something”, falls in “Volition” basic event schema. Since different parameters of grammaticalization are applied on the verb in the grammaticalization process, the verb xāstan transforms to a complex schema. As an auxiliary verb and in serial complex schema, xāstan conceptualizes the future tense. In the same complex schema but in different contexts, the verb expresses proximative and avertive aspects. When the verb xāstan falls in evaluative complex schema, it conceptualizes a new notion of modality in which the speaker requests addressee the permission of actualizing the verb by proposing a suggestion; as a result, it is called proposal modality. The main explanation of polygrammaticalization of the verb xāstan in Persian seems to be filling the functional gaps and satisfying the need of conceptualizing the grammatical functions not met by other grammatical forms.