As far as I know, the first auxiliary is normally treated as the head of a verb phrase (VP) in the X-Bar theory.

He was writing a letter.

In this sentence, for example, the first auxiliary, was, is normally treated as the head of the VP, was writing a letter, in the X-Bar theory.

In some respect, however, the first auxiliary, was, is merely indicating the tense and aspect of the following verb writing.

Therefore, I wonder if the first auxiliary was can be treated as the specifier of the VP and the following lexical verb writing as the head of the VP in some variant of the X-Bar theory, or if this kind of treatment is a no go in any variant thereof.


You are right that the auxiliary is merely a TAM carrier, it's a function word without any meaning of its own. It's however completely logical to take it to be the structural head of the "verb phrase" (the whole IP). People often confuse categorial and functional heads. The auxiliary is the head of the IP because we can "observe" this constituent in the sentence. However the functional head is the V because it's the (only) content word giving the IP its meaning. (The situation would be a little more complicated in the presence of a light verb.)

In sum, it's safe to say that taking the auxiliary to be a specifier would be (as you put it) "a no go in any variant of X' theory", at least as far as English is concerned.

  • Thanks. So the only specifier of a VP in any X' theory has to be an adverb phrase? – JK2 Mar 19 '18 at 2:20
  • According to Wikipedia, an adverbial is an adjunct, not a specifier; but then it says that the specifier of a verb phrase is a quantifier, such as 'each' or 'all', which is lunacy -- those are appositives of the subject. – amI Mar 20 '18 at 23:44
  • @JK2 As mentioned by aml, adverb phrases are adjuncts. – Atamiri Mar 21 '18 at 12:20
  • @amI Floating quantifiers can be specifiers, they create nonprojectivity so they can't be attached directly to their NPs in phrase-structure grammars. – Atamiri Mar 21 '18 at 12:22
  • In, He definitely was writing a letter, isn't definitely the specifier of the VP? If an adverb cannot be the specifier of a VP, could you tell me what can be along with some example? – JK2 Mar 22 '18 at 1:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.