(1) Arbitrariness is the core feature of language, which refers to the fact that there is no logical or intrinsic connection between a particular sound and the meaning it is associated with. A good example is the fact that different sounds are used to refer to the same object in different languages. Arbitrariness of language makes it potentially creative, and conventionality of language makes a language be passed from generation to generation. For example, it is unable to explain why a book is called a /buk/ and a pen a/pen/.

(2) However, there seems to be different levels of arbitrariness. ①Arbitrary relationship between the sound of a morpheme and its meaning. You may object to this when you think of words with different degrees of onomatopoeia, namely, words that sound like the sounds they describe. But in English, totally different words are used to describe the sound. For example, bark in English and 汪汪 in Chinese. ②Arbitrariness at the syntactic level. According to systemic functionalists and American functionalists, language is not arbitrary at the syntactic level. As we know, the order of elements in a sentence follows certain rules, and there is a certain degree of correspondence between the sequences of clauses and the real happenings. In other words, syntax is less arbitrary than words. E.g., there are two sentences. “He came in and sat down”.“He sat down and came in”. The first sentence means that the man came in first and then he sat down, but the second sentence means the opposite, perhaps he got into his wheelchair and propelled himself into the room. ③Arbitrary and Convention, convention means you have to say things in this way and you cannot change the expression any other way. For learners of a foreign language, it is the conventionality of a language that is more worth noticing than its arbitrariness. That may be why when we are burying ourselves in memorizing idioms, we feel nothing of the aibitrariness of the language but are somewhat tortured by its conventionality.