In X-bar theory, what is the role of the intermediate projection (X')?
AIt names the grammatical category of the phrase (e.g., NP, VP).
BIt is the head word itself — the single lexical item.
CIt groups the head with its complements before specifiers are added.
DIt marks the boundary between one clause and the next.
X' (X-bar) is the intermediate level that combines the head (X) with its complement(s). The specifier then combines with X' to form the maximal projection (XP). This three-level hierarchy — X, X', XP — is the core architectural claim of X-bar theory.
Question 2 True / False
X-bar theory is primarily a descriptive notation for drawing phrase trees rather than a claim about how grammars generate sentences.
TTrue
FFalse
Answer: False
This is a common misconception. X-bar theory is a generative principle: it proposes that all phrases, across all categories and all languages, are built by the same hierarchical rule (X → Specifier + X', X' → X + Complement). The tree format is a representation of that generative claim, not the claim itself.
Question 3 Short Answer
How does X-bar theory account for the fact that noun phrases, verb phrases, and prepositional phrases all behave similarly despite having different head types?
Think about your answer, then reveal below.
Model answer: X-bar theory proposes a universal template — head (X), intermediate projection (X'), and maximal projection (XP) — that applies to every phrasal category. The head category (N, V, P, etc.) varies, but the hierarchical structure is identical, so all phrase types share the same combinatorial properties.
The power of X-bar theory is precisely this unification: a single schema generates all phrase types by substituting different head categories. This explains cross-categorial symmetry (e.g., why you can modify a noun phrase and a verb phrase with similar structural positions) without requiring separate rules for each phrase type.