Wittgenstein (1953) points out that vague language is very useful for the predominant apply of human being’s language. Words just like fuzzy pictures: we can’t replace an unnatural photograph to a sharp one, and the unclear picture is always what we need. There’re no strict boundaries to distinguish vague language. No matter how ambiguous about Wittgenstein’s notion of vague terms and those rules, he contributes to the usefulness of vague language, and his concept of vague rules also highlights the sources and nature of vague language.
Ullmann(1962) stresses the importance of vague language from other aspect. He thinks that one condition is not fixed, it has many aspects and results from many causes. Some vague language is based on the nature language, whereas some of them work in a very special circumstance. He regards vague language as four aspects:
a. generic character of words;
b. meaning is never homogeneous(i.e. it is context-bound);
c. lack of clear-cut boundaries in the non-linguistic world;
d. lack of familiarity with what the words stand for. 模糊语言在商务谈判中的应用(3):http://www.751com.cn/yingyu/lunwen_21168.html