Prototype Theory and Its Applications to Studying Existential Sentence Types in Vietnamese Language

In the field of cognitive semantics, prototype theory started in mid-1970s together with studies by Eleanor Rosch, a psycholinguist, on the internal structure of categories. The advent of these studies marked a new era of doing research on lexical semantics and led to reviewing the classical approach of classification from the Aristotelian period on. The application of the prototype approach to determining various levels of categorization, in which the basic level is the center from which other cognitive activities are analyzed, has achieved certain success. In recent years, prototype theory is considered a new direction in conducting research on linguistics in general and the Vietnamese language in particular at the time when traditional viewpoints have not been able to satisfactorily explain various linguistic issues whose analyses are not agreed upon. The effectiveness of prototype theory is shown by the fact that those members that are more prototypical within a category are recognized and understood faster, more frequently used, and that in turn helps to accelerate the speed of solving any tasks which are related to the task of identifying, and especially those of explaining the ‘fuzziness’ phenomenon. This paper mainly focuses on introducing the basic and important content of prototype theory. Then, the paper proposes certain applications of the theory to conducting research on the Vietnamese phonology, lexicon, grammar with an emphasis on studying in depth Vietnamese existential sentences.