Complement ClauseEdit
Complement Clause
Complement clauses are subordinate clauses that supply the content of a larger expression. They complete the meaning of a verb, an adjective, or a noun in the main clause, functioning as its object, its subject predication, or its complement. In English, they are a central device for reporting thought and speech, attributing beliefs, desires, or emotions, and for embedding information within discourse. Common forms include that-clauses, wh-clauses, and nonfinite clauses such as infinitives and participial constructions. The study of complement clauses intersects with core topics in syntax, semantics, and language variation, and it has practical implications for education, the interpretation of law and policy language, and the design of natural language processing systems Clause Syntax.
In the tradition of careful, conventional usage, complement clauses contribute to clear communication by packaging content as distinct units within a sentence. When a speaker says, for example, "She believes that the project is viable," the embedded content is carried by the that-clause that the project is viable. Alternatively, in "I wonder whether he will come," a wh- or whether-clause serves as the content of the mental state expressed by wonder. In many contexts, the choice of form—whether to insert that, whether to use a wh-clause, or to employ a nonfinite infinitive—can affect readability, emphasis, and the perceived formality of the prose. The interlocking of main clause meaning and embedded content is a fundamental feature of human language, and it appears with remarkable regularity across languages, though the exact realizations vary from one linguistic system to another That-clause Wh-clause Nonfinite clause.
Foundations
Complement clauses are distinguished by their function and by the mechanism that marks their status as content-bearing units. Several layers of organization are involved:
Finite vs nonfinite: Finite complement clauses carry a tensed form and are often introduced by a complementizer like that or by a wh-word (as in "I know who came"). Nonfinite complement clauses do not have a full tense system of their own and often surface as to-infinitives or participial clauses (as in "I want to leave" or "Seeing the weather, he stayed indoors"). The distinction has implications for agreement, binding, and the assignment of roles to subject arguments in the main clause Finite clause Nonfinite clause.
Complementizers and markers: The boundary between the main clause and the embedded clause is commonly marked by a complementizer such as that, or by a wh-word in wh-questions, or by the absence of an overt marker in certain contexts (null complementizers). The selection of a particular form can reflect the speaker’s intention, formality, and dialectal background. See also Complementizer for the functional category responsible for signaling embedded content That-clause.
The morphosyntactic relationship: Complement clauses can follow verbs of saying, thinking, perceiving, and reporting, or they can complete adjectives and nouns that express attitude, belief, or assertion. Different verb classes exhibit distinct preferences for certain kinds of complement clauses, and cross-linguistic variation can be substantial. See discussions of Control (linguistics) and Raising (linguistics) for the ways in which the subject and other arguments can be linked between the main and embedded clauses Control (linguistics) Raising (linguistics).
Content and interpretation: The embedded content is not merely syntactic decoration; it encodes propositions, beliefs, desires, or judgments. The truth-conditions of the embedded clause contribute to the overall assertion of the main clause, which raises interesting questions in semantics about belief and attitude report, factivity, and evidentiality. See Semantics for how complement clauses participate in propositional attitude ascriptions.
Types of complement clauses
That-clauses: The most common finite form, introduced by the subordinating conjunction that in many contexts but often omitted in casual speech or formal writing. The presence or absence of that can affect ambiguity and cadence, but the content remains the same. See That-clause for a fuller treatment of this form.
Wh-clauses: Embedded questions such as "where" or "who" that provide the content of a verb or adjective. These often surface with a wh-word fronted in the embedded clause and carry information about information-seeking or specification. See Wh-clause for a deeper look at how these function within sentences.
Whether- and if-clauses: Finite clauses expressing doubt, contingency, or inquiry about truth values. They are especially common after verbs of thinking, asking, or hoping. See Whether-clause and If-clause in related discussions.
To-infinitive clauses: Nonfinite clauses headed by to, functioning as the complement of verbs like want, need, or intend. They express purpose, intention, or future-facing content. An example is "She intends to move next year." See to-infinitive for more on this widely used nonfinite form.
Bare infinitive and -ing clauses: Nonfinite clauses without to, or with gerund/participial forms, used after verbs of perception, verbs of causation, and certain other verbs. English often uses bare infinitives in sentences like "I heard him sing" or "We let him go." See Bare infinitive and Gerund for related discussions.
Finite vs nonfinite alternations: In some cases, the same semantic content can be expressed with either a finite or nonfinite form, producing subtle shifts in emphasis or in the flow of discourse. The choice can reflect register, rhetorical effect, or syntactic constraints in particular languages. See Finite clause and Nonfinite clause for comparisons.
Syntactic structure and relationships
Complement clauses are not standalone content; they are connected to the main clause through a set of syntactic relations that govern how the embedded clause takes its place in the sentence. Important theoretical concepts include:
Complementizers: The head that introduces the embedded clause—such as that, if, whether, or a null marker—helps define the type of content and how it interacts with the main clause. See Complementizer for a general machinery that languages employ to mark embedded content.
Control and PRO: In many languages, the subject of an embedded nonfinite clause is controlled by a nominal or pronoun in the main clause. This gives rise to phenomena like null subjects (PRO) and the distinction between overt and covert controllers. See Control (linguistics) for a full account of how argument structure is shared across clauses.
Raising and embedding: In some constructions, the apparent subject of the embedded clause may originate in the main clause, a phenomenon known as raising. This has implications for how we assign case, theta-roles, and binding relationships across clauses. See Raising (linguistics) for more.
The boundary and extraction: In wh-clauses, the wh-word often moves to the front of the main clause, leaving behind a trace or a stretched dependency. The behavior of these extractions is a central topic in modern theories of syntax and phrase structure. See Wh-movement and Dependency for related ideas.
Cross-linguistic variation and historical notes
Complement clauses show remarkable variation across languages. While many languages rely on explicit complementizers, others use particles, word order changes, or case marking to encode embedded content. Some languages require overt markers for content clauses in contexts where English permits a bare clause, while others suppress markers entirely in colloquial speech. Historical development in languages like English includes processes such as the optionality of that in many contexts, the emergence of null complementizers, and the reanalysis of sentence structure in narrative and formal prose. See Historical linguistics for background on how complement clauses evolve over time, and Cross-linguistic studies for comparisons across language families.
Use in discourse and literature
Complement clauses enable speakers and writers to convey nuanced stance, belief, and intention. In public discourse and documentation, the choice of complement form can signal formality, authority, or modesty. For instance, writing that uses clearer that-clauses in policy descriptions can reduce ambiguity in legal and regulatory texts, whereas more concise, less explicit forms may be preferred in informal communication. The ability to embed content is also central to reporting structures in journalism and parliamentary proceedings, where complex statements must be conveyed accurately and efficiently. See Discourse for a broader view of how embedded clauses function in narrative and argument.
Debates and controversies
As with many areas of grammar and usage, debates around complement clauses track broader tensions between traditional standards and modern descriptivist approaches. From a perspective that values clarity, efficiency, and established usage in formal writing, some points of contention include:
Prescriptivism vs descriptivism: Critics of strict prescriptive rules argue that language naturally evolves, and that grammar descriptions should reflect actual usage rather than enforce rigid templates. Proponents of traditional standards contend that clear rules promote comprehension, reduce ambiguity, and aid learning. See Prescriptive grammar and Descriptive linguistics for the two sides of this long-running debate.
The role of that in formal writing: Some style guides advocate maintaining that in written prose to ensure explicitness, while others tolerate its omission in many contexts to create tighter, more economical sentences. The balance between brevity and clarity remains a live issue in editorial practice. See That-clause for discussions of this form and its usage.
That-deletion and ambiguity: The optional nature of that can sometimes lead to ambiguity or misreading, especially in complex sentences or in automated parsing. Advocates of conservative usage emphasize keeping that to minimize misinterpretation, while others view frequent deletion as normal and non-problematic in everyday language. See That-clause for further detail on usage variation.
Education and language policy: Debates over how complement clauses should be taught in schools reflect broader policy questions about literacy, standard English, and dialect preservation. Some education advocates advocate for strong coverage of traditional structures to ensure students can navigate formal texts; others push for broader tolerance of nonstandard forms to reflect real-world usage. See Education policy and Standard language for related topics.
Woke criticisms and the language of instruction: Critics who stress reforms in language to align with inclusive communication sometimes argue that traditional grammar holds back marginalized groups. From a more conventional standpoint, these criticisms are viewed as distractions that overstate cultural power plays and underplay the practical importance of intelligibility and consistency in instruction. They are often dismissed as overreach when they presume that grammar is a tool of oppression rather than a shared mechanic of communication. See discussions under Language and society for how social factors intersect with grammar, and Linguistic prescription for a deeper look at how normative ideas influence teaching and policy.