【Abstract】Fuzzy set theory and its development have made a profound influence in peoples life， especially in communication because people live in the communicative society. Sometimes the fuzzy language brings a much stronger expression function than the accurate language. Fuzzy language can not only express the fuzzy information but also convey the accurate information. Some people believe that the linguistic expression should be as precise as possible in humans communication. In fact， the application of fuzzy words from cognative perspective can let complicated languaga phonomena clear. Fuzzy words are analyzed detailedly from cognativ perspective in the paper to indicate the importance and neccesity of fuzzy expressions.

【Key words】fuzzy words； the application； cognative perspective

The study of fuzziness from the perspective of cognitive linguistics has a profound significance and practical value. Cognitive linguistics is an approach to linguistic study that is based on our experience of the world and the way we perceive and conceptualize it. It makes the fuzzy linguistics has a great development after it melts into cognitive linguistics and becomes a part of it.

1. Prototype Theory and Family Resemblances

The world consists of infinite variety of objects with different substances， shapes and colors. When we open our eyes every morning， we can see lights， trees， birds， rivers， etc. All of them are categories. We can recognize sparrows and magpies， and we cannot consider a car as a kind of bird. All these classifications can be conceived as a mental process. “This mental process of classification is now commonly called categorization， and its product is the cognitive categories.” The object， which has the most typical features in a category， is often considered as prototype. But prototype is abstract， and every prototype in a category is only an instance of the abstract prototype.

Prototype and family resemblance are two important characteristics of category， analyzing the semantic fuzzy phenomena in the category theory， and the principle of family resemblances can interpret many linguistic phenomena， which cannot be illustrated in traditional category theory and semantic theory. They have an applied value in the research of semantic fuzziness.

2. The Illustration of Prototype Theory to Semantic Fuzziness

In cognitive linguistics， semantic fuzziness is a category with a central meaning. The central meaning of a fuzzy word may be most clearly recognized and most easily remembered， while meanings that are farther away from the centre will be fuzzier and more difficult to be memorized because of their low membership. J.Aitchison （1987） once wrote：“Words have fuzzy edges， in that for the majority of words it is impossible to specify a hard core meaning at all.”endprint

Fuzzy words are the fundamental elements of semantic fuzziness. Fuzzy words in a sentence can directly lead to the fuzzy meaning of a sentence. Now， some fuzzy words （adjectives， nouns） will be taken as examples in order to explain fuzzy semantics synthetically.

2.1 Typical Experiment of Fuzziness and Its Influence

The fuzzy concepts may be most clearly illustrated by Berlin and Kays experiment （1969） in which Berlin and Kay examined the semantic fuzziness of color terms resulting from demarcation of color field as a continuum in optics. Before them， most researchers in this field believed that color categories are totally arbitrary.14 They found evidence that we rely on the so-called focal colors for color categorization. “The set of chips was composed of 329 color chips， 320 of which represented 40different colors， or， more precisely 40 hues， each divided into eight different levels of brightness. The remaining nine chips were white， black， and seven levels of grey”.

In categorizing colors， people rely on certain points in the color space for orientation. For example， if the speakers are asked to point out the best example of the color “red”， the hue of “red” which they think is familiar， that is focal color. In sum， color categorization is anchored in focal colors. Focal colors are shared the same by different speakers in different language communications. In peoples consciousness， prototype is the most typical thing possessing all the features of the category it belongs to， though it will be changed according to many factors， including geography， culture and the different individual point of view.

As Wu Tieping proclaimed， the things and phenomena in the objective world are far more rich and variable than those that can be represented by any classifications， or words which denote these classifications. Berlin and Kays experiment about the classification of color is the first time to bring fuzzy set theory into the prototypical research of color categories， and they also combine the fuzzy logic and mathematical logic inference and operation. Moreover， they offer the description of the cognitive characteristics to semantic categories with a formalization model and methodology.

2.2 Some Emblematical Examples of Fuzzy Words

Fuzzy words can be divided into fuzzy nominal words， fuzzy adjectival words and fuzzy qualifiers， etc. For instance， “past， bird， tree” are nominal fuzzy words； “short， tall， young” are adjectival fuzzy words； “a bit， a lot of， many” are fuzzy qualifiers.endprint

When we use a Chinese word “香” to refer to the taste of rice or a dish， we can not describe the taste exactly. “香” initially arise from “Literature Analyzing and Word Study”. The original meaning of it is “a sense of smell”. Afterwards， it was transferred from the sense of smell into a sense of taste， such as in the phrase “飯好香”. In Modern Chinese Dictionary（1979）， “香” has eight meanings， one means “good-smell” opposite to “stink”， i.e. “香水”， “香皂”； the second meaning is to describe the good taste of food， i.e. “飯很香”. In English， we often use a compound word to express “香” which is a “good taste”.

Therefore， from these we know that the central meaning of the Chinese word “香” is “a good smell or taste”. As a category， the boundary of “香” is not clear， too. “香” and “臭” have not a clear-cut boundary. Some people like mustard， because they think it is delicious， while others do not. Furthermore， Does “durians” has a good taste or a bad taste？ Is it “香”or “臭”？ Some people who dislike it consider it as “臭”， but some people who like to eat it say it is “香”. This shows the boundary between the two words cannot be cut clearly. Its fuzzy.

Take another nominal fuzzy word “monkey” for example. According to COBILD English Dictionary （2003）， “monkey” is an animal with a long tail which lives in hot countries； monkeys climb trees， and belong to the same family as gorillas and chimpanzees. That is to say， monkeys， gorillas and chimpanzees are in the same grade. But in Modern Chinese Dictionary （1979）， “monkey” is defined as “a kind of mammal. It has many kinds， and a similar shape like a human being， there is hair on its body， most of them are in grey or in brown color， it has a long tail and dexterous in action， living in groups， eats fruits， edible wild herbs， and insects.”. Simultaneously， “Chimpanzee” in this dictionary is explained as “a kind of mammal， bigger than monkey， it has long arms and eats fruits”. But in Advanced Learners English-Chinese Dictionary （6th Edition）， the explanation of chimpanzee is “an animal like a large monkey without a tail”. In accordance with these materials， we get the two pieces of information. One is， people define things diversely， while the other is， the kind of monkey we are familiar with is in the centre of the “monkey” category. It is the prototype. Chimpanzees are also in this category， but are very far from the prototype. They are in the borderline position， even if there are big differences between the chimpanzees and monkeys both in shape and other characteristics， they connect together for family resemblances principle.endprint

In sum， fuzzy words have their original meanings and prototypes. There is also a transition zone between a fuzzy word and its neighbor fuzzy word. The transition zone is also fuzzy， just like “evening” and “night”. The study of fuzzy words in prototype theory can make semantic fuzziness more detailed and deeper.

2.3 The Necessity of Category Theory in the Research of Fuzzy Words

Many scholars and linguists have studied semantic fuzziness before Zadeh， but they havent made a great development in this field. Zadehs fuzzy set theory brings a strong tool to semantic fuzziness， thus becoming a revolutionary variation in the research of semantic fuzziness. Semantic fuzziness is not only a problem in language application any more， but is a category， which can be described by the fuzzy set theory. One of the root causes that fuzzy-set theory applying in the fuzziness research is that linguistic categories are exactly the fuzzy set in some field. Simultaneously， since language has its economic principle， it causes the semantic fuzziness inevitably. That is to say， the semantic fuzziness of categories is a certain outcome of language economy. This is also the necessity in human communication16. Consequently， the research of fuzzy words in category theory is helpful to comprehend the phenomena in communication.

3. Summary

All the categories people learn are keeping their inner attributes and relations they originally have. These relations will not be interrupted by compartmentalization. On the contrary， the transition zones are fuzzy because of the inner relationship of entities. Categorization in nature is a tool of human recognizing and understanding the object entities， consequently， having research on fuzzy semantics in cognitive knowledge is necessary， and can be helpful to recognize the inner causes the accurate words dont analyze. If there are no such perceptions in communication， the fuzzy utterances will not be understood.

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作者簡介：李權(quán)格（1977-），女，漢族，吉林四平人，講師，碩士，主要研究方向?yàn)槟：Z言學(xué)及英語教學(xué)法。endprint