In
linguistics
Linguistics is the scientific study of language. The areas of linguistic analysis are syntax (rules governing the structure of sentences), semantics (meaning), Morphology (linguistics), morphology (structure of words), phonetics (speech sounds ...
(especially
generative grammar
Generative grammar is a research tradition in linguistics that aims to explain the cognitive basis of language by formulating and testing explicit models of humans' subconscious grammatical knowledge. Generative linguists, or generativists (), ...
), a complementizer or complementiser (
glossing abbreviation: ) is a
functional category (part of speech) that includes those words that can be used to turn a
clause
In language, a clause is a Constituent (linguistics), constituent or Phrase (grammar), phrase that comprises a semantic predicand (expressed or not) and a semantic Predicate (grammar), predicate. A typical clause consists of a subject (grammar), ...
into the
subject or
object
Object may refer to:
General meanings
* Object (philosophy), a thing, being, or concept
** Object (abstract), an object which does not exist at any particular time or place
** Physical object, an identifiable collection of matter
* Goal, an a ...
of a
sentence. For example, the word ''that'' may be called a complementizer in
English sentences like ''Mary believes that it is raining''. The concept of complementizers is specific to certain modern grammatical theories. In traditional grammar, such words are normally considered
conjunctions. The standard abbreviation for ''complementizer'' is C.
Category of C
C as head of CP
The complementizer is often held to be the syntactic
head
A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple ani ...
of a full clause, which is therefore often represented by the abbreviation CP (for ''complementizer
phrase
In grammar, a phrasecalled expression in some contextsis a group of words or singular word acting as a grammatical unit. For instance, the English language, English expression "the very happy squirrel" is a noun phrase which contains the adject ...
''). Evidence of the complementizer functioning as the head of its clause includes that it is commonly the last element in a clause in
head-final languages like
Korean or
Japanese in which other heads follow their
complements, but it appears at the start of a clause in
head-initial
In linguistics, head directionality is a proposed Principles and parameters, parameter that classifies languages according to whether they are head-initial (the head (linguistics), head of a phrase precedes its Complement (linguistics), complement ...
languages such as
English in which heads normally precede their complements.
The trees below illustrate the phrase "Taro said that he married Hanako" in Japanese and English; syntactic heads are marked in red and demonstrate that C falls in head-final position in Japanese, and in head-initial position in English.
Sources of C
It is common for the complementizers of a language to develop historically from other syntactic categories, a process known as
grammaticalization
Grammaticalization (also known as grammatization or grammaticization) is
a linguistic process in which words change from representing objects or actions to serving grammatical functions. Grammaticalization can involve content words, such as noun ...
.
C can develop from a determiner
Across world languages,
pronoun
In linguistics and grammar, a pronoun (Interlinear gloss, glossed ) is a word or a group of words that one may substitute for a noun or noun phrase.
Pronouns have traditionally been regarded as one of the part of speech, parts of speech, but so ...
s and
determiner
Determiner, also called determinative ( abbreviated ), is a term used in some models of grammatical description to describe a word or affix belonging to a class of noun modifiers. A determiner combines with a noun to express its reference. Examp ...
s are especially commonly used as complementizers (e.g., English ''that'').
:''I read in the paper that it's going to be cold today.''
C can develop from an interrogative word
Another frequent source of complementizers is the class of
interrogative word
An interrogative word or question word is a function word used to ask a question, such as ''what, which'', ''when'', ''where'', '' who, whom, whose'', ''why'', ''whether'' and ''how''. They are sometimes called wh-words, because in English most ...
s. It is especially common for a form that otherwise means ''what'' to be borrowed as a complementizer, but other interrogative words are often used as well, as in the following colloquial English example in which unstressed ''how'' is roughly equivalent to ''that''.
:''I read in the paper how it's going to be cold today.''
C can develop from a preposition
With non-finite clauses, English ''for'' in sentences like ''I would prefer for there to be a table in the corner'' shows a preposition that has arguably developed into a complementizer. (The sequence ''for there'' in this sentence is not a
prepositional phrase
An adpositional phrase is a syntactic category that includes ''prepositional phrases'', ''postpositional phrases'', and ''circumpositional phrases''. Adpositional phrases contain an adposition (preposition, postposition, or circumposition) as he ...
under this analysis.)
C can develop from a verb
In many languages of
West Africa
West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...
and
South Asia
South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...
, the form of the complementizer can be related to the verb ''say''. In those languages, the complementizer is also called the quotative, which performs many extended functions.
Empty complementizers
Some analyses allow for the possibility of invisible or
"empty" complementizers. That is considered to be present if there is no word even though the rules of grammar expect one. The complementizer (for example, "that") is usually said to be understood. An English-speaker knows that it is there and so it does not need to be said. Its existence in English has been proposed based on the following type of alternation:
:''He hopes you go ahead with the speech''
:''He hopes that you go ahead with the speech''
Because ''that'' can be inserted between the verb and the embedded clause without changing the meaning, the original sentence without a visible complementizer would be reanalyzed as
:''He hopes ∅
C you go ahead with the speech''
Where the symbol ''∅
C'' represents the empty (or "null") complementizer, that suggests another interpretation of the earlier "how" sentence:
:''I read in the paper <how> ∅
C t's going to be cold today'
where "how" serves as a specifier to the empty complementizer, which allows for a consistent analysis of another troublesome alternation:
:''The man <whom> ∅
C saw yesterdayate my lunch!''
:''The man <OP> ∅
C saw yesterdayate my lunch!''
:''The man <OP> that
saw yesterdayate my lunch!''
where "OP" represents an invisible interrogative known as an
operator.
In a more general sense, the proposed empty complementizer parallels the suggestion of near-universal empty
determiner
Determiner, also called determinative ( abbreviated ), is a term used in some models of grammatical description to describe a word or affix belonging to a class of noun modifiers. A determiner combines with a noun to express its reference. Examp ...
s.
Various analyses have been proposed to explain when the empty complementizer ''∅'' can substitute for a phonologically overt complementizer. One explanation is that complementizers are eligible for omission when they are
epistemically neutral or redundant. For example, in many environments, English's epistemically neutral ''that'' and Danish's can be omitted. In addition, if a complementizer expresses a semantic meaning that is also expressed by another marker in the phrase, the complementizer that carries the redundant meaning may be omitted. Consider the complementizer in
Mbula, which expresses uncertainty, in the following example:
Here, the marker also expresses epistemic uncertainty, so can be replaced by the phonologically null complementizer without affecting meaning or grammaticality.
Complementizers are present in a wide range of environments. In some, C is obligatorily overt and cannot be replaced by the empty complementizer. For example, in English, CPs selected for by manner-of-speaking verbs (''whisper, mutter, groan'', etc) resist C-drop:
:''Barney whispered *(that) Wilma was dating Fred.''
:''Barney said (that) Wilma was dating Fred.''
In other environments, the complementizer can be omitted without loss of grammaticality but may result in semantic ambiguity. For example, consider the English sentence ''"The newspaper reported that a new mayor was elected and'' (''that'') ''there was a riot."'' Listeners can infer a causal relationship between the two events reported by the newspaper. A new mayor was elected, and as a result, there was a riot. Alternatively, the events may be interpreted as independent of each other. The non-causal interpretation is more likely when the second complementizer ''that'' is present, but the causal interpretation is more likely when an empty complementizer is present.
The ambiguity here arises because the sentence in which the second complementizer is empty may also be interpreted as simply having no second complementizer. In the former case, the sentence involves co-ordination of CPs, which lends itself more easily to a non-causal interpretation, but the latter case involves co-ordination of TPs, which is the necessary structure for a causal interpretation. Partial syntax trees for the possible structures are given below.
Selectional restrictions imposed by C
As a syntactic head, C always
selects for a complement tense phrase (TP) whose syntax and semantics are dictated by the choice of C. The choice of C can determine whether the associated TP is finite or non-finite, whether it carries the semantic meaning of certainty or uncertainty, whether it expresses a question or an assertion, etc.
Propositions vs. indirect questions
The following complementizers are available in English: ''that, for, if, whether, ∅''.
''If'' and ''whether'' form CPs that express
indirect question
In grammar, a content clause is a dependent clause that provides content implied or commented upon by an independent clause. The term was coined by Danish linguist Otto Jespersen. Content clauses have also traditionally been called noun clauses ...
s:
:''John wonders whether / if it is raining outside.''
In contrast, the complementizers ''for, that,'' as well as the phonologically null complementizer ''∅'', introduce "
declarative or non-interrogative" CPs.
:''John thinks ∅ it is raining outside.''
:''John thinks that it is raining outside.''
:''John prefers for it to be raining.''
Finite vs. non-finite TPs
Tense phrases in English can be divided into finite (tensed) clauses or non-finite (tenseless) clauses. The former includes an indication of the relative time when its content occurs; the latter has no overt indication of time. Compare ''John will leave'' (John's leaving will take place in the future) with ''John wants to leave'' (we are unsure when John is leaving).
Certain complementizers strictly select for finite clauses (denoted
finite while others select for non-finite clauses (denoted
finite.

Complementizers ''if, that'' require
tenseTP:
:''Mary wishes that she will win the game.'' (future)
:''Mary believes if she wins the game, she can date John.'' (present)
Complementizer ''for'' requires a
tenseTP:
:''Mary hopes for Kate to win the game.'' (infinitive)
Complementizer ''whether'' allows either
tenseor
tenseTP:
:''John wonders whether Mary will win the game.'' (future)
:''Mary wonders whether to win the game or not.'' (infinitive)
Epistemic selection
Complementizers frequently carry
epistemic meaning about the speaker's degree of certainty, such as whether they are doubtful, or the speaker's source of information, such as whether they are making an inference or have direct evidence. Contrast the meaning of "if" and "that" in English:
:''John doesn't know if Mary is there.''
:''John doesn't know that Mary is there.''
"If" signals that the associated tense phrase must carry the epistemic meaning of uncertainty. In contrast, "that" is epistemically neutral. The contrast is not uncommon cross-linguistically. In languages with only two complementizers, one is frequently neutral, and the other carries the meaning of uncertainty. One such language is
Lango (a Nilotic language spoken in Uganda):
Additional languages with the neutrality/uncertainty complementizer contrast include several European languages:
In other languages, complementizers are richer in epistemic meaning. For example, in
Mbula, an Austronesian language of Papua New Guinea, the following complementizers are available:
More generally, complementizers have been found to express the following values cross-linguistically: certainty, (general) uncertainty, probability, negative probability/falsehood, apprehension, and reportativity.
Complementizers in Itzaj Maya also demonstrate epistemic meaning. For instance, English ''that'' and Itzaj Maya are used not only to identify complements but also to introduce relative clauses:
(1a) introduces a subordinate clause and (1b) introduces a conditional clause, similar to English. The former subtype ''that'' can be defined in terms of ''information source'' and includes meanings glossed as direct evidence, indirect evidence, hearsay, inferential. The latter subtype ''if'' can be defined in terms of ''degree of certainty'' and includes meanings glossed as certainty, probability, epistemic possibility, doubt. Thus, epistemic meaning as a whole can be defined in terms of the notion of ''justificatory support''.
Complementizer stacking
Itzaj Maya can even combine the neutral complementizer, , with the non-neutral, , as is illustrated in examples (2a) in which the neutral complementizer occurs alone and (2b) in which it is optionally inserted in front of the uncertainty complementizer :

In (1a,b) and (2a), each complementizer can be licensed once within the clause, but in (2b), the significant difference of Itzaj Maya from English is observed. English can license multiple C as long as the clause is completed with the embedded V or D. For example, I saw that fox that ran towards the garden that Tommy took care of. In such cases, C can appear as the complement of V or D many times. However, CP-recursion in two tiers or CP appearing as an immediate complement of maximal projection CP cannot be allowed in English. That action of ''Complementizer Stacking'' is realised as ungrammatical.
In Scandinavian languages, however, the phenomenon of complementizer stacking occurs. For example, researchers observed the two basic types of CP-recursion that occur independently in Danish: a CP with V2 (i.e. a CP headed by a lexical predicate in its head position) will be referred as CP ("big CP"), and a CP without V2 (i.e. CP headed by a non-lexical element) will be referred to as cP ("little cP").
*
P c° [– LEXICAL ("little cP")
* [cP [+ LEXICAL">��_LEXICAL.html" ;"title="P c° [– LEXICAL">P c° [– LEXICAL ("little cP")
* [cP [+ LEXICAL ("big CP")
The case of little/big CPs are comparable to the "VP shell" structure in English, which introduces a small v in the higher position in the tree and big V in the lower position in the tree.
In the examples, Danish also allows complementizer stacking in constructions involving subject extraction from complement and relative clauses in colloquial speech:
Complementizers are indeed stacked together in the beginning of the clause and act as a complement of DP. CP-recusion structure on the right is applied for each of the clause, which points to evidence of complementizer stacking in Danish. In addition, the combination of ''som at der'' in (3a) is possible in only one specific order, which led the researchers to believe that s''om'' may not require an empty operator in its Spec-CP position.
In various languages
Assyrian Neo-Aramaic
In Assyrian Neo-Aramaic, a modern Aramaic language, (or , depending on the dialect) is used as a complementizer and is related to the
relativizer In linguistics, a relativizer (list of glossing abbreviations, abbreviated ) is a type of Conjunction (grammar), conjunction that introduces a relative clause. For example, in English, the conjunction ''that'' may be considered a relativizer in a s ...
. It is less common in casual speech but more so in formal conversation.
Hebrew
In
Hebrew
Hebrew (; ''ʿÎbrit'') is a Northwest Semitic languages, Northwest Semitic language within the Afroasiatic languages, Afroasiatic language family. A regional dialect of the Canaanite languages, it was natively spoken by the Israelites and ...
(both Modern and Ancient), two complementizers co-exist: , which is related to the
relativizer In linguistics, a relativizer (list of glossing abbreviations, abbreviated ) is a type of Conjunction (grammar), conjunction that introduces a relative clause. For example, in English, the conjunction ''that'' may be considered a relativizer in a s ...
''asher'' ( <
Akkadian ''ashru'' 'place') and/or to the pronominal Proto-Semitic ''dhu'' ('this'); and ×›Ö´Ö¼×™
i which is also used as a conjunction meaning 'because, when'. In modern usage, the latter is reserved for more formal writing.
American Sign Language
Some manual complementizers exist in
American Sign Language
American Sign Language (ASL) is a natural language that serves as the predominant sign language of Deaf communities in the United States and most of Anglophone Canadians, Anglophone Canada. ASL is a complete and organized visual language that i ...
, but they are usually expressed non-manually by
facial expressions
Facial expression is the motion and positioning of the muscles beneath the skin of the face. These movements convey the emotional state of an individual to observers and are a form of nonverbal communication. They are a primary means of conveying ...
.
Conditional clauses, for example, are indicated by raised eyebrows. A manual complementizer, if used, is also accompanied by a facial expression. The non-manual marking of complementizers is a common phenomenon found in many sign languages, and it has even been suggested by Fabian Bross that C-categories are universally marked with the face in sign languages.
See also
*
X-bar theory#Structure of S'
*
Dependent clause
A dependent clause, also known as a subordinate clause, subclause or embedded clause, is a certain type of clause that juxtaposes an independent clause within a complex sentence. For instance, in the sentence "I know Bette is a dolphin", the claus ...
*
ECM verb
*
That-clause
References
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COMP:complementizer
A:set A person marker
ITS:incompletive transitive status
CTS:completive transitive status
COMPL:completive aspect
ABST:abstract
ABIL:abilitive
INDIR:indirect (object)
{{lexical categories, state=collapsed
Syntactic categories
Parts of speech
Grammatical marker type
Subordinators