Editing X-bar theory (section)

== Structure of sentence ==
=== Structure of S ===
Under the PSR, the structure of '''S''' (sentence) is illustrated as follows.<ref name="C55" /><ref name="C57" /><ref name="C75">{{Cite book|last=Chomsky|first=Noam|authorlink= |title=The Logical Structure of Linguistic Theory|publisher=Plenum Press|location=New York|language= |year=1981|page= |id= |isbn= |quote= }}</ref>
* S → NP (Aux) VP
However, this structure violates the headedness principle because it has an exocentric, headless structure, and would also violate the binarity principle if an [[Auxiliary verb|Aux]] (auxiliary) occurs, because the S node will then be ternary-branching. Given these, Chomsky (1981)<ref name="C81" /> proposed that S is an '''InflP''' headed by the functional category '''[[inflection|Infl]]'''(ection), and later in Chomsky (1986a),<ref name="C86a" /> this category was relabelled as '''I''' (hence constitutes an '''IP'''), following the notational convention that phrasal categories are represented in the form of XP, with two letters.{{refn|group="FN"|The functional category I was later replaced by '''T'''(ense) and '''Agr'''(eement) along the proposal by Pollock (1989).<ref>{{Cite journal|last=Pollock|first=Jean-Yves|date=1989|title=Verb Movement, Universal Grammar, and the Structure of IP|journal=Linguistic Inquiry|volume=20|issue=3|pages=365–424}}</ref> The functional category Agr, however, was rejected by Chomsky (1995)<ref name="C95b">{{cite book|last=Chomsky|first=Noam|title=The Minimalist Program |date=1995 |publisher=MIT Press |location=Cambridge MA}}</ref> because it presumably made no contributions at LF. For this reason, clauses are generally assumed to be '''TP'''s headed by the functional category '''T''' in contemporary linguistic theory.}} The category I includes auxiliary verbs such as ''will'' and ''can'', clitics such as ''-s'' of the third person singular present and ''-ed'' of the past tense. This is consistent with the headedness principle, which requires that a phrase have a head, because a sentence (or a clause) necessarily involves an element that determines the inflection of a verb.

Assuming that S constitutes an IP, the structure of the sentence ''John studies linguistics at the university'', for example, can be illustrated as in Figure 10.{{refn|group="FN"|{{Anchors|Affix hopping|Affix movement}}In the structure in Figure 10, the [[linear order (linguistics)|linear order]] of the whole sentence is derived by '''affix hopping''' (also known as '''affix movement'''). Affix hopping is an operation that is applied at [[phonological form]] (PF) after syntactic formation, and in this case, it serves to move the "sound" of the inflectional suffix /-s/ and adjoin it onto the verb.<ref>{{Cite book|editor-last1=Araki|editor-first1=Kazuo|authorlink= |translator= |year=1999|title=Eigogaku Yogo Jiten (A Dictionary of Technical Terms of English Linguistics)|publisher=Sanseido|location=Tokyo|page=16|id= |isbn= |quote= }}</ref> Chomsky (1981)<ref name="C81" /> calls this kind of tense affix movement ''Rule R''.}}
[[File:The_X-bar_structure_of_"John_studies_linguistics_at_the_university".png|thumb|none|600px|Figure 10]]
As is obvious, the IP hypothesis makes it possible to regard the grammatical unit of sentence as a phrasal category. It is also important that the configuration in Figure 10 is fully compatible with the central assumptions of the X-bar theory, namely the headedness principle and the binarity principle.

=== 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.}}

=== Other phrasal structures ===
* '''[[VP-internal subject hypothesis]]''': A hypothesis on the inner structure of VP proposed by researchers such as Fukui and Speas (1986)<ref>Fukui, Naoki and Speas, Margaret J. (1986) Specifiers and Projection. ''MIT Working Papers in Linguistics'' '''8''': 128–172.</ref> and Kitagawa (1986).<ref>Kitagawa, Yoshihisa (1986). ''Subjects in Japanese and English'', Unpublished doctoral dissertation, University of Massachusetts. Reprinted in Kitagawa (1994), Routledge.</ref> It assumes that the sentential subject is base-generated in Spec-VP, not in Spec-IP.
* '''DP Hypothesis''': A hypothesis proposed by Abney (1987),<ref>Abney, Steven P. (1987). ''The English Noun Phrase in Its Sentential Aspect''. Doctoral dissertation, MIT.</ref> according to whom noun phrases are not NPs but DPs headed by the functional category D.
* '''VP shell''': An analysis put forth by Larson (1988),<ref>Larson, Richard K. (1988). On the Double Object Construction. ''Linguistic Inquiry'' '''19''' (3): 335–391.</ref> which assumes two-layered structures of VP. Later in Chomsky (1995a,<ref name="C95a">{{Cite book |last=Chomsky |first=Noam |title=Evolution and revolution in linguistic theory |date=1995 |publisher=Georgetown University Press |isbn=978-0-87840-248-9 |editor-last=Campos |editor-first=Héctor |location=Washington, D.C. |pages=51–109 |chapter=Bare Phrase Structure |editor-last2=Kempchinsky, Paula Marie}}</ref> 1995b<ref name="C95b" />), the higher VP was replaced by ''v''P headed by the functional category ''v'' (little/small v, traditionally written in italics).
* '''PredP Hypothesis''': A hypothesis proposed by Bowers (1993,<ref>{{Cite journal|last=Bowers|first=John|date=1993|title=The Syntax of Predication|journal=Linguistic Inquiry|volume=24|issue=|pages=591–656}}</ref> 2001<ref>Bowers, John (2001). Predication. In: Mark Baltin and Chris Collins (eds.), ''The Handbook of Contemporary Syntactic Theory'', 299–333, Blackwell.</ref>), according to whom [[small clause]]s<ref>Stowell, Timothy (1981). ''Origins of Phrase Structure''. Doctoral dissertation, MIT.</ref> are PredPs headed by the functional category Pred.
* '''[[Bare Phrase Structure]]''' (BPS): A replacement of the X-bar theory put forth by Chomsky (1995a,<ref name="C95a" /> 1995b<ref name="C95b" />). It dispenses with a "template" structure like the X-bar schema, and yields syntactic structures by (iterative applications of) an operation called [[Merge (linguistics)|Merge]], which serves to connect two syntactic objects such as words and phrases into one. Some radical versions of it even reject syntactic category labels such as V and A. See also [[Minimalist Program]].