Editing X-bar theory (section)

=== Structure of S' ===
Words that introduce [[subordinate clause|subordinate]] or [[complement clause]]s are called '''[[complementizer]]s''',<ref name="radford-C">{{Cite book|last=Radford|first=Andrew|authorlink= |translator= |year=2016|title=Analysing English Sentences: Second Edition|publisher=Cambridge University Press|location=Cambridge|pages=86–99|id= |isbn= |quote= }}</ref> and representative of them are ''that'', ''if'', and ''for.''{{refn|group="FN"|Sometimes, ''whether'' is also regarded as a complementizer, but many researchers such as Nakajima (1996)<ref>{{Cite journal|last=Nakajima|first=Heizo|date=1996|title=Complementizer Selection|journal=The Linguistic Review|volume=13|issue=2|pages=143–164|doi=10.1515/tlir.1996.13.2.143 |s2cid=201091227 }}</ref> analyze that ''whether'' does not occur in the head position of CP, but in the specifier position of CP ('''Spec-CP'''), just as [[wh-words]] do. This amounts to saying that ''whether'' is not a C<sup>0</sup>: It is subject to debate as to which syntactic category it belongs to.}} Under the PSR, complement clauses were assumed to constitute the category '''S''''.<ref name="B70">{{Cite journal|last=Bresnan|first=Joan|date=1970|title=On Complementizers: Toward a Syntactic Theory of Complement Types|journal=Foundations of Language|volume=6|issue=|pages=297–321}}</ref><ref name="B72">Bresnan, Joan (1972) ''Theory of Complementation in English Syntax'', Doctoral dissertation, MIT.</ref><ref name="B79">{{Cite book|last=Bresnan|first=Joan|authorlink= |translator= |year=1979|title=Theory of Complementation in English Syntax|publisher=Garland|location=New York|page=|id= |isbn= |quote= }}</ref>
* S' → COMP S
Chomsky (1986a)<ref name="C86a" /> proposed that this category is in fact a '''CP''' headed by the functional category '''C'''.<ref name="radford-C" /> The sentence ''I think that John is honest'', for example, then has the following structure.
[[File:The_structure_of_"I_think_that_John_is_honest".png|thumb|none|700px|Figure 11]]
Moreover, Chomsky (1986a)<ref name="C86a" /> assumes that the landing site of [[wh-movement]] is the specifier position of CP ('''Spec-CP'''). Accordingly, the [[Wh question|wh-question]] ''What did John eat?'', for example, is derived as in Figure 12.{{refn|group="FN"|[[Wh-movement]] is subject to Chomsky's (1973)<ref>Chomsky, Noam (1973). Conditions on Transformations. In: Stephen R. Anderson and Paul Kiparsky (eds.) ''A Festschrift for Morris Halle'', 232–286. New York: Holt, Rinehart, and Winston.</ref> '''[[subjacency condition]]''', and is applied in a '''successive cyclic''' manner, thus via every Spec-CP.}}
[[File:The_structure_of_"What_did_John_eat?".png|thumb|none|450px|Figure 12]]
In this derivation, the I-to-C movement is an instance of '''[[subject-auxiliary inversion]]''' (SAI), or more generally, '''[[head movement]]'''.{{refn|group="FN"|See Baker (1988)<ref>Baker, Mark C. (1988). ''Incorporation: A Theory of Grammatical Function Changing''. Chicago: University of Chicago Press.</ref> for details.}}