Relative clauses in the English language are formed principally by means of relative pronouns. The basic relative pronouns are who, which, and that; who also has the derived forms whom and whose. Various grammatical rules and style guides determine which relative pronouns may be suitable in various situations, especially for formal settings. In some cases the relative pronoun may be omitted and merely implied ("This is the man [that] I saw", or "This is the putter he wins with").
Modern guides to English say that the relative pronoun should take the case (subject or object) which is appropriate to the relative clause, not the function performed by that clause within an external clause.
The words used as relative pronouns have other uses in English grammar: that can be a demonstrative or a conjunction, while which, what, who, whom and whose can be interrogatives. For other uses of whoever etc., see -ever.
The choice of relative pronoun typically depends on whether the antecedent is human or a thing (that is, a non-human): for example, who and its derivatives (whom, whoever, etc.--apart from whose) are generally restricted to human antecedents, while which and what and their derivatives refer in most cases to things, including animals.
The relative pronoun that is used with both human and non-human antecedents. Some writers and style guides recommend reserving that for non-human cases only, but this view does not reflect general use. Counter-examples can be found in literature: Shakespeare (the man that hath no music in himself, in The Merchant of Venice), Mark Twain (The Man that Corrupted Hadleyburg), and Ira Gershwin (The Man that Got Away); and informal English, especially speech, follows an actual practice (in using that and which) that is more natural than prescriptivist.
The possessive form whose is necessarily used with non-human as well as human antecedents because no possessive forms exist for which or that. Otherwise, to avoid, for example, using whose in "...the car whose engine blew up.." would require a periphrastic phrasing, such as "...the car the engine of which blew up", or "...the car of which the engine blew up".
English also makes the distinction between human vs. thing in personal pronouns (he, she vs. it) and certain other pronouns (such as someone, somebody vs. something); but some particular things--such a navy ships and marine vessels--are described with female pronouns, and pets and other animals are frequently addressed in terms of their gender or their (anthropomorphic) 'personhood'. Typically, it is when these things-as-human become antecedents to relative clauses that their relative pronouns tend to revert to that or which--for things--rather than taking the regular who, whom, etc., for human referents. See Gender in English.
The distinction between restrictive, or integrated, relative clauses and non-restrictive, or supplementary, relative clauses in English is shown not only in speaking (through prosody), but also in writing (through punctuation): a non-restrictive relative clause is preceded by a pause in speech and a comma in writing, whereas a restrictive clause is not. Compare the following sentences, which have two quite different meanings, and correspondingly two clearly distinguished intonation patterns, depending on whether the commas are inserted:
The first expression refers to an individual builder (and it implies we know, or know of, the builder--the referent). It tells us that he builds "very fine" houses, and that he will make a large profit. It conveys these meanings by deploying a non-restrictive relative clause and three short intonation curves, marked-off by commas. The second expression refers not to a single builder but to a certain category, also called a set, of builders who meet a particular qualification, or distinguishing property: the one explained by the restrictive relative clause. Now the sentence means: it is the builder who builds "very fine" houses who will make a large profit. It conveys this very different meaning by providing a restrictive relative clause and only one intonation curve, and no commas. Commas are however often used erroneously, probably because this rule is taught based on logic and most people are not aware that they can in this case trust their ear in deciding whether to use a comma or not. (English uses commas in some other cases based on grammatical reasons, not prosody.)
Thus, in speaking or writing English prose, if it is desired to provide a restrictive rather than non-restrictive meaning (or vice versa) to the referent, then the correct syntax must be provided--by choosing the appropriate relative clause (i.e., restrictive or non-restrictive) and the appropriate intonation and punctuation.
To analyse whether a relative clause is restrictive or non-restrictive a simple test can be applied: If the basic meaning of the sentence (the thought) is not changed by removing the relative clause, the relative clause is not essential to the basic thought and is non-restrictive. But if the essential meaning of the thought is disturbed, the relative clause is restrictive.
Restrictive relative clauses are also called integrated relative clauses, defining relative clauses, or identifying relative clauses. Conversely, non-restrictive relative clauses are called supplementary, appositive, non-defining or non-identifying relative clauses.
Although the term "restrictive" has become established as joined with integrated clauses, there are integrated clauses that do not necessarily express a distinguishing property of the referent. Such a (so-called) restrictive clause--actually a non-restrictive clause--is so completely integrated into the narrative and intonation of the main sentence that it appears to be restrictive, though it is not.
Examples of integrated relative clauses in this sense that are not truly restrictive:
When the "restrictive" relative clause is removed from either of the above sentences, the antecedent ("the father" and "the clergyman") is not placed in question: in the first example, for instance, there is no suggestion that the narrator has two fathers--because the relative clause is not expressing a distinguishing property of the subject. Instead, here the relative clause is integrated but it is not truly restrictive.
The distinction between the relative pronouns that and which to introduce restrictive relative clauses with non-human antecedents is a frequent point of dispute.
For clarity, we can look at a slightly modified version (that is, for the case of non-human antecedents) of the example above:
Of the two, it is consensus that only which is commonly used in non-restrictive clauses.
Equivalently, the two cases would be applied where the statements are logically:
The dispute concerns restrictive clauses. Both that and which are commonly used. However, for "polished" prose, many American style guides, such as the 16th edition of The Chicago Manual of Style, recommend generally avoiding which in restrictive relative clauses. This prescriptive 'rule' was proposed as early as 1851 by Goold Brown. It was championed in 1926 by H. W. Fowler, who said, "If writers would agree to regard that as the defining [restrictive] relative pronoun, and which as the non-defining, there would be much gain both in lucidity and in ease. Some there are who follow this principle now; but it would be idle to pretend that it is the practice either of most or of the best writers." Linguists, according to Stanford linguist Arnold Zwicky, generally regard the proposed rule on not using which in restrictive relative clauses as "a really silly idea".
Which cannot correctly be replaced by that in a restrictive relative clause when the relative pronoun is the object of a non-stranded (or non-dangling) preposition. In this case which is used, as in "We admired the skill with which she handled the situation." (The example is taken from The Cambridge Grammar of the English Language.)
English, unlike other West Germanic languages, has a zero relative pronoun (denoted below as Ø)--that is, the relative pronoun is implied and not explicitly written or spoken; it is "unvoiced". This measure is used in restrictive relative clauses (only) as an alternative to voicing that, which or who, whom, etc. in these clauses:
In other words, the word "that" (or "who" or "which", etc.) as a relative clause connector is optional when it would not be the subject of the relative clause; even when it would be required in other languages.
The zero relative pronoun cannot be the subject of the verb in the relative clause; that is, that or who, etc., cannot be omitted (unvoiced) if the zero pronoun would be a subject. Thus one may say:
but never (except in some varieties of colloquial English):
Neither the unvoiced zero pronoun nor that can be used in non-restrictive relative clauses (that is, yes: "Jack, who builds houses, built the house she lives in", but never: "Jack, that builds houses, built ... "), nor in any relative clause with a fronted preposition (yes: "Jack built the house in which we live", but never: "Jack built the house in that we live"). But either can be used when the preposition is stranded, or dangled, ("Jack built the house that we live in," or "Jack built the house we live in.")
Relative clauses headed by zeros are frequently called contact clauses in TEFL contexts, and may also be called "zero clauses".
(If that is analyzed as a complementizer rather than as a relative pronoun the above sentences would be represented differently: Jack built the house that I was born in Ø; Jack built the house I was born in Ø; He is the person I saw Ø.
Some varieties of English use what as a relative pronoun. For example, in Guardians of the Galaxy Vol. 2, a Ravager says, "For it is a name what strikes fear into the hearts of anyone what hears it."
What as a relative pronoun appeared on the front-page of United Kingdom newspaper The Sun on 11 April 1992 in the headline "It's The Sun Wot Won It."
Standard Englishes proscribe the use of what as a relative pronoun, preferring who or that.
A relative pronoun often appears as the object of a preposition, both in restrictive and non-restrictive clauses, as in
It is not unusual to place the preposition at the end of the relative clause, while the relative pronoun that it governs is placed at the beginning of the clause or omitted, so
is also possible. A preposition is never placed in front of the relative pronoun that, but preposition stranding is possible when there is an explicit that, or when the relative pronoun representing the object of the clause is omitted. So
are possible but
Such preposition-stranding is perfectly grammatical and has been used by the best writers for centuries, though it was, in the past, criticized by prescriptivist grammarians as being either ungrammatical or informal.
The grammatical case of a relative pronoun governed by a preposition is the same as when it is the direct object of a verb: typically the objective case. When the relative pronoun follows the preposition, the objective case is required, as in
is ungrammatical. In the case of the construction with a stranded preposition, however, the subjective form (e.g. "who") is commonly used, as in
especially in informal style. Use of the objective case with a stranded preposition, as in
is somewhat rare, but occasionally found, even in informal style.
Variations may be encountered in the spoken and informal English, but the most common distribution of the forms of pronouns in relative clauses follows:
|Subject||who, that||which, that||who||which|
|Object of verb||who, whom, that, Ø||which, that, Ø||who, whom||which|
|Attached object of preposition||whom||which||whom||which|
|Detached object of preposition||who, whom, that, Ø||which, that, Ø||who, whom||which|
|Possessive||whose, of whom||whose, of which||whose, of whom||whose, of which|
The word that, when used in the way described above, has been classified as a relative pronoun; however, according to some linguists it ought to be analyzed instead as a subordinating conjunction or relativizer. This is consistent with that used as a conjunction in (I said that I was tired), or implied in (I said I was tired).
According to Rodney Huddleston and Geoffrey Pullum, that is not a relative pronoun but a subordinator, and its analysis requires a relativized symbol R as in (The film that I needed [R] is not obtainable). Here R is the covert direct object of the verb "needed" and has "the film" as an antecedent. A similar analysis is required when that is omitted and implied, as in (The film I needed is not obtainable).
There are some grammatical differences between that and the (other) relative pronouns: that is limited to restrictive relative clauses, and it cannot be preceded with a preposition. There are also similarities between the (purported) relative pronoun that and the ordinary conjunction that: the weak pronunciation /ð?t/ is (almost invariably) used in both cases, and both of them are frequently omitted as implied.
English allows what is called a free, fused or nominal relative construction. This kind of relative construction consists of a relative clause that instead of attaching to an external antecedent--and modifying it as an external noun phrase--is "fused" with it; and thus a nominal function is "fused" into the resultant 'construction'. For example:
Here "What he did" has the same sense as "that which he did", or "the thing that he did". Thus the noun phrase the thing and the relative pronoun that are 'fused' into what; and the resulting relative construction "What he did" functions as the subject of the verb was. Free relative constructions are inherently restrictive.
English has a number of "fusible" relative pronouns that initiate relative constructions, including what, whatever and whoever. But these pronouns introduce other clauses as well; what can introduce interrogative content clauses ("I do not know what he did") and both whatever and whoever can introduce adverbials ("Whatever he did, he does not deserve this"). See -ever.
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Some nonfinite clauses, including infinitive and participial clauses, may also function as relative clauses. These include:
For further examples see Uses of English verb forms § Uses of nonfinite verbs.
Some adverbial clauses can function as relative clauses, including:
Relative clauses in English usually employ gapping. For example, in the sentence "This is the man that I saw", there is a gap after the word saw. The shared noun phrase the man is understood to fill that gap ("I saw [the man]"). However, gapless relative clauses do occur in non-standard English. One form of gapless relatives uses a resumptive pronoun. In a 1990 article, Ellen Prince observed that such constructions were common in spoken English, though officially ungrammatical. For example:
In this case, removing the underlined resumptive pronoun results in an acceptable gapped relative clause:
In other cases, the resumptive pronoun is used to work around a syntactic constraint, as in:
In this example, the word it occurs as part of a wh-island. Attempting to extract it gives an unacceptable result:
Gapless relative clauses may also occur without a resumptive pronoun, such as:
. . . the facts of usage are quite simple. Virginia McDavid's 1977 study shows that about 75 percent of the instances of which in edited prose introduce restrictive clauses; about 25 percent nonrestrictive ones. We conclude that at the end of the 20th century, the usage of which and that--at least in prose-- has settled down. You can use either which or that to introduce a restrictive clause-- the grounds for your choice should be stylistic--and which to introduce a nonrestrictive clause.
The use of which for that is common in written and spoken language. . . . Occasionally which seems preferable to that . . .
"In polished American prose, that is used restrictively to narrow a category or identify a particular item being talked about . . .; which is used nonrestrictively . . . Which should be used restrictively only when it is preceded by a preposition . . .
Most linguists--especially sociolinguists--think this a really silly idea, but some people, like Safire, seem to have never met a rule they didn't like, especially if the rule would bring order into apparent chaos.