否定是否有歧义尚无定论。单义派的一些研究试图通过证明元语否定标记的缺失推翻否定歧义说。为了反驳这一论断，进而证明否定语用歧义的存在，本文以汉语的“是”为例，在元表达框架内证明某些常见于元语否定的语言形式并不是专门的元语否定标记。借助三域理论，本文进一步证明否定在行、知、言三域的语用歧义。为了标识否定所处的认知域，某些元语言否定需要特殊的语言形式，这些形式不但不能推翻否定歧义，反而证明了语用歧义的存在。

Whether the negation is ambiguous or univocal has not yet been determinated. Some studies of monoguist approach argue that the ambiguity of negation cannot be justified unless there are marks of metalinguistic negation. In order to prove the invalidity of this argument and to support the pragmatic ambiguity of negation, taking shi in Chinese as an example, this paper proves in the framework of metarepresentation that some linguistic forms often used in metalinguistic negations are not particular marks of metalinguistic negation. With the theory of three domains, this paper proves that the pragmatic ambiguity of negation does not exist between metalinguistic negation and descriptive negation, but in the three cognitive domains. In order to identify the cognitive domain in which the negation is located, some metalinguistic negation requires a special linguistic form, whose existence should not overthrow the ambiguity of negation but prove the pragmatic ambiguity of negation.