The purpose of this research is twofold: firstly, it is to clarify the syntactic and semantic status of the copula be; secondly, it is to see how much light the copula be and argue that the copula be is light enough to be a null copula at the position of a light verb v of vP without a specifier. I argue that the copula be is an impoverished category and the lightness of copula be is a pure instantiation of a functional head v, in which a little v introduces verbal predicates as well as external arguments. The proposal in this paper is supported by synchronic and diachronic data. The optional existence of the null copula in synchronic grammatical diversities like child acquisition, standard English casual speech, journal headlines, rhetoric, and African American Vernacular English (AAVE) is discussed to prove the lightness of copula be. Diachronically, the grammaticalization shows that the null copula can be a by-product of copularization in the unidirectionality of grammaticalization in English.
2. The Syntax of the Copula Be as a Light Verb
3. Null Copula: The Grammatical Deletion of the Copula Be
3.1 The Omission of the Copula Be in Child Acquisition
3.2 The Omission of the Copula Be in Grammatical Diversity
4. Diachronic Grammaticalization of the Copula Be