There are three issues in the definition of Modern Chinese. First, the tree connections between Modern Chinese and Mandarin lead to polysemy of Modern Chinese: ：○1 Modern Chinese equals Mandarin and Modern Chinese doesn’t include Modern Chinese dialects. ○2 The definition of Modern Chinese have board sense and narrow sense. In board sense, it includes Mandarin and Modern Chinese dialects and in narrow sense, it just includes Mandarin. ○3 Modern Chinese include Mandarin and Modern Chinese dialects, but it doesn’t equal Mandarin. The discussion about the relation of Modern Chinese and Mandarin continue at least 60 years. This linguistic phenomenon was concerned and discussed by scholars since the mid of 1950s or even earlier. Second, the definition of the users of Modern Chinese reveals the incompletion of Modern Chinese’s definition. The existing definition can’t summarize the users of Modern Chinese comprehensively and it causes the incompletion of Modern Chinese’s definiton. Third, Han nationality is used to define Modern Chinese but one of the elements of nationality’s definition is language. It is a circular reasoning that Modern Chinese and Nationality are defined by each other. As described above, the lack of objective criterion of the measurement method of traditional linguistics lead to polysemy, incompletion and circular reasoning of the definition of Modern Chinese. And then it results in the confusion of Modern Chinese’s definition. The measurement method of Speech community theory can overcome polysemy and incompletion of the definition, and avoid the circular reasoning mistake. Modern Chinese is one of the language codes of the community of Modern Chinese. The community of Modern Chinese is a speech community formed by people who identity Modern Chinese. It is composed by five key elements: population, area, identification, interaction, facility.

“現代漢語”在定義上存在三個問題。 第一，“現代漢語”和“現代漢民族共同語”之間的三種關係，導致“現代 漢語”定義的“多義性”：○1 “現代漢語”等同於“現代漢民族共同語”，“現代 漢語”不包括現代漢語方言；○2 “現代漢語”分廣義和狹義的概念，廣義上包括 “現代漢民族共同語”和現代漢語方言，狹義上等同於“現代漢民族共同語”， 不包括現代漢語方言；○3 “現代漢語”包括“現代漢民族共同語”和現代漢語方 言，不等同於“現代漢民族共同語”。關於“現代漢語”和“現代漢民族共同語” 的關係的討論至少持續了六十年，從上世紀五十年代中期開始或更早，直到今天 都是被各位專家學者和科研組織所關注和討論的語言學現象。 第二，從當前對“現代漢語”語言使用者的界定狀況來看，表現出“現代漢 語”定義的不完整性的問題。就是說已有的定義并不能夠很好地全面地概括“現 代漢語”這門語言所有的使用者，造成了“現代漢語”定義的不完整性。 第三，對“現代漢語”進行定義都使用“漢民族”來定義，而定義“民族” 的要素之一是語言，“現代漢語”和“民族”之間互相定義，出現了“循環論證” 的情況。 以上是傳統語言學方法因其測定的過程缺乏客觀標準而導致了“現代漢語” 定義的多義性、不完整性和“循環論證”誤區，進而造成“現代漢語”概念的混 淆。“言語社區理論”的界定方法可以克服定義的多義性和不完整性，跳出“循 環論證”的誤區。 “現代漢語”是“現代漢語社區”的一種語言代碼並且是“現代漢語社區” 的主導語言，“現代漢語社區”是一個由認同“現代漢語”的人群構成的言語社 區，由人口、地域、認同、互動、設施五要素構成。