{{Short description|Using 'do' in negated clauses, questions, and other constructions}} {{DISPLAYTITLE:''Do''-support}}{{English grammar}} '''''Do''-support''' (sometimes referred to as '''''do''-insertion''' or '''periphrastic ''do''''') in English grammar is the use of the auxiliary verb ''do'' (or one of its inflected forms, e.g. ''does'') to form negated clauses and constructions which require subject–auxiliary inversion, such as questions.
The verb ''do'' can be used optionally as an auxiliary even in simple declarative sentences, usually as a means of adding emphasis (e.g. "I ''did'' shut the fridge."). However, in negated and inverted clauses, ''do'' is usually used in today's Modern English. For example, in idiomatic English, the negating word ''not'' cannot attach directly to just any finite lexical verb; rather, it can only attach to an auxiliary or copular verb. For example, the sentence ''I am not'' with the copula ''be'' is fully idiomatic, but ''I know not'' with the finite lexical verb ''know'', while grammatical, is archaic. If there is no other auxiliary present when negation is required, the auxiliary ''do'' is used to produce a form like ''I do not (don't) know.'' The same applies in clauses requiring inversion, including most questions: inversion must involve the subject and an auxiliary verb, so it is not idiomatic to say ''Know you him?''; today's English usually substitutes ''Do you know him?''
''Do''-support is not used when there is already an auxiliary or copular verb present or with non-finite verb forms (infinitives and participles). It is sometimes used with subjunctive forms. Furthermore, the use of ''do'' as an auxiliary should be distinguished from the use of ''do'' as a normal lexical verb, as in ''They do their homework''.
==Common uses== ''Do''-support appears to accommodate a number of varying grammatical constructions: #question formation, #the appearance of the negation ''not'', and #negative inversion. These constructions often cannot occur without ''do''-support or the presence of some other auxiliary verb.
===In questions=== The presence of an auxiliary (or copular) verb allows subject–auxiliary inversion to take place,<ref name=Kaplan>{{Citation |title=English Grammar: Principles and Facts |last=Kaplan |first=Jeffrey P. |place=Englewood Cliffs, New Jersey |publisher=Prentice-Hall |year=1989}}</ref><ref name=Huddleston /> as is required in most interrogative sentences in English. If there is already an auxiliary or copula present, ''do''-support is not required when forming questions:
:* '''''He will''' laugh.'' → '''''Will he''' laugh?'' (the auxiliary ''will'' inverts with the subject ''he'') :* '''''She is''' at home.'' → '''''Is she''' at home?'' (the copula ''is'' inverts with the subject ''she'')
This applies not only in yes–no questions but also in questions formed using interrogative words:
:* ''When '''will he''' laugh?''
However, if there is no auxiliary or copula present, inversion requires the introduction of an auxiliary in the form of ''do''-support:
:* ''I know.'' → '''''Do I''' know?'' (Compare: ''*Know I?{{efn|This article uses asterisks to indicate ungrammatical examples.}}'') :* ''He laughs.'' → '''''Does he''' laugh?'' (Compare: ''*Laughs he?'') :* ''She came home.'' → '''''Did she come''' home?'' (Compare: ''*Came she home?'')
The finite (inflected) verb is now the auxiliary ''do''; the following verb is a bare infinitive which does not inflect: ''does he '''laugh'''?'' (not ''laughs''); ''did she '''come'''?'' (not ''came'').
In negated questions, the negating word ''not'' may appear either following the subject or attached to the auxiliary in the contracted form ''n't''. This applies to both ''do''-support and other auxiliaries:
:* ''Why '''are you not''' playing? / Why '''aren't you''' playing?'' :* '''''Do you not''' want to try? / '''Don't you''' want to try?''
The above principles do not apply to ''wh''-questions if the interrogative word is the subject or part of the subject. Then, there is no inversion and so there is no need for ''do''-support: ''Who lives here?'', ''Whose dog bit you?''
The verb ''have'', in the sense of possession, is sometimes used without ''do''-support as if it were an auxiliary, but this is considered dated. The version with ''do''-support is also correct:
:* ''Have you any idea what is going on here?'' :* '''''Do you have''' any idea what is going on here?'' :* (''Have you got any idea what is going on here?'' – the order is similar to the first example, but ''have'' is an auxiliary verb here)
For elliptical questions and tag questions, see the elliptical sentences section below.
===With ''not''=== In the same way that the presence of an auxiliary allows question formation, the appearance of the negating word ''not'' is allowed as well.<ref name="Kaplan"/><ref name=Huddleston /> Then too, if no other auxiliary or copular verb is present, ''do''-support is required.<ref name=Kaplan/><ref name=Huddleston /><ref name=DeCapua>{{Cite book|last=DeCapua |first=Andrea |title=Grammar for Teachers |publisher=Springer |year=2008}}</ref><ref name=Heidinger>{{Cite book|last=Heidinger |first=Virginia |title=Analyzing Syntax and Semantics |publisher=Gallaudet U Press |year=1984}}</ref>
:* ''He '''will''' laugh.'' → ''He '''will not''' laugh.'' (''not'' attaches to the auxiliary ''will'') :* ''She laughs.'' → ''She '''does not''' laugh.'' (''not'' attaches to the added auxiliary ''does'')
In the second sentence, ''do''-support is required because idiomatic Modern English does not allow forms like ''*She laughs not''. The verb ''have'', in the sense of possession, is sometimes negated thus:
:* ''I '''haven't''' the foggiest idea.''
Most combinations of auxiliary/copula plus ''not'' have a contracted form ending in suffix ''-n't'', such as ''isn't'', ''won't'', etc. The relevant contractions for negations formed using ''do''-support are ''don't'', ''doesn't'' and ''didn't''. Such forms are used very frequently in informal English.
''Do''-support is required for negated imperatives even when the verb is the copula ''be'':
:*'''''Do not''' do that.'' :*'''''Don't be''' silly.''
However, there is no ''do''-support with non-finite verb forms, as they are negated by a preceding ''not'':
:*''It would be a crime '''not to help''' him'' (the infinitive ''to help'' is negated) :*'''''Not knowing''' what else to do, I stood my ground'' (the present participle ''knowing'' is negated) :*'''''Not eating vegetables''' can harm your health'' (the gerund ''eating'' is negated)
With subjunctive verb forms, such as a present subjunctive, ''do'' is infrequently used for negation, which is frequently considered ambiguous or incorrect because it resembles the indicative. The usual method to negate the present subjunctive is to precede the verb with a ''not'', especially if it is ''be'' (since using ''do''-support with it, whether indicative or subjunctive, is ungrammatical):
:*''I suggest that he '''not receive''' any more funding'' (the present subjunctive ''receive'' is negated) :*''It is important that he '''not be''' there'' (the present subjunctive ''be'' is negated)
As a past subjunctive, however, ''did'' is needed for negation (unless the verb is ''be'', whose past subjunctive is ''were''):
:*''I wish that he '''did not know''' it'' :*''I wish that he '''were not''' here''
The negation in the examples negates the non-finite predicate. Compare the following competing formulations:
:*''I '''did not''' try to laugh.'' vs. ''I tried '''not to laugh'''''. :*''They '''do not''' want to go.'' vs. ''They want '''not to go'''''.
There are two predicates in each of the verb chains in the sentences. ''Do''-support is needed when the higher of the two is negated; it is not needed to negate the lower nonfinite predicate.
For negated questions, see the questions section above. For negated elliptical sentences, see the elliptical sentences section below.
===Negative inversion=== The same principles as for question formation apply to other clauses in which subject–auxiliary inversion is required, particularly after negative expressions and expressions involving ''only'' (negative inversion):
:* ''Never '''did he''' run that fast again.'' (wrong: ''*Never he did run that fast again. *Never ran he that fast again.'') :* ''Only here '''do I''' feel at home.'' (wrong: ''*Only here feel I at home.'')
==Further uses== In addition to providing ''do''-support in questions and negative clauses, the auxiliary verb ''do'' can also appear in contexts where it is not grammatically required. In such cases, its use often serves pragmatic functions, such as emphasis or contrast.
===For emphasis=== {{uncited section|date=September 2025}} The auxiliary generally appears for purposes of emphasis, for instance to establish a contrast or to express a correction: :* ''Did Bill eat his breakfast? Yes, he '''did''' eat his breakfast'' (''did'' emphasizes the positive answer, which may be unexpected). :* ''Bill doesn't sing, then. No, he '''does''' sing'' (''does'' emphasizes the correction of the previous statement).
As before, the main verb following the auxiliary becomes a bare infinitive, which is not inflected (one cannot say *''did ate'' or *''does sings'' in the above examples).
As with typical ''do''-support, that usage of ''do'' does not occur with other auxiliaries or a copular verb. Then, emphasis can be obtained by adding stress to the auxiliary or copular:
:* ''Would you take the risk? Yes, I '''would''' take the risk.'' :* ''Bill isn't singing, then. No, he '''is''' singing.''
(Some auxiliaries change their pronunciation when stressed, such as ''can'' {{IPAc-en|k|ən}} → {{IPAc-en|k|ae|n}}; see Weak and strong forms in English.)
In negative sentences, emphasis can be obtained by adding stress either to the negating word (if used in full) or to the contracted form ending in ''n't''. That applies whether or not ''do''-support is used:
:* ''I '''wouldn't''''' (or ''would '''not''''') ''take the risk.'' :* ''They '''don't''''' (or ''do '''not''''') ''appear on the list.''
Emphatic ''do'' can also be used with imperatives, including with the copula ''be'':
:* ''Do take care! Do be careful!''
===In elliptical sentences=== The auxiliary ''do'' is also used in various types of elliptical sentences, where the main verb is omitted (it can be said to be "understood", usually because it would be the same verb as was used in a preceding sentence or clause). That includes the following types:
*Tag questions: ** ''He plays well, '''doesn't he?''''' ** ''You don't like Sara, '''do you?''''' *Elliptical questions: ** ''I like pasta. '''Do you?''''' ** ''I went to the party. Why '''didn't you?''''' *Elliptical answers: ** ''Do you want to come along? — '''I do.''''' (emphasis on ''do'') ** ''Who took the car? — '''He did.''''' (emphasis on ''he'') *Elliptical statements: ** ''They swam, but '''I didn't'''.'' ** ''He looks smart, and so '''do you'''.'' ** ''You fell asleep, and '''I did''', too.''
Such uses include cases that ''do''-support would have been used in a complete clause (questions, negatives, inversion) but also cases that (as in the last example) the complete clause would normally have been constructed without ''do'' (''I fell asleep too''). In such instances ''do'' may be said to be acting as a pro-verb since it effectively takes the place of a verb or verb phrase: ''did'' substitutes for ''fell asleep''.
As in the principal cases of ''do''-support, ''do'' does not normally occur when there is already an auxiliary or copula present; the auxiliary or copula is retained in the elliptical sentence:
:*''He '''is''' playing well, '''isn't''' he?'' :*''I '''can''' cook pasta. '''Can''' you?'' :*''You '''should''' get some sleep, and I '''should''' too.''
However, it is possible to use ''do'' as a pro-verb (see below section #Pro-verbs & Do-so Substitution even after auxiliaries in some dialects:
*''Have you put the shelf up yet? — I haven't done'' (or ''I haven't'')'', but I will do'' (or ''I will''). (However it is not normally used in this way as a ''to''-infinitive: ''Have you put the shelf up? I plan to'', rather than *''I plan to do''; or as a passive participle: ''Was it built? Yes, it was'', not *''Yes, it was done''.)
Pro-verbal uses of ''do'' are also found in the imperative: * ''Please do. — Don't!''
===Pro-verbs and do-so substitution=== The phrases ''do so'' and ''do what'' for questions are pro-verb forms in English. They can be used as substitutes for verbs in x-bar theory grammar to test verb phrase completeness. Bare infinitives forms often are used in place of the missing pro-verb forms.
Examples from Santorini and Kroch:<ref name="Syntax of Natural Language">{{cite web |url= https://www.ling.upenn.edu/~beatrice/syntax-textbook/ |title= Syntax of Natural Language |last1= Santorini |first1= Beatrice |last2 = Kroch |first2 = Anthony |date= 2007 |website=ling.upenn.edu/~beatrice/syntax-textbook/ |access-date= 29 July 2020 }}</ref>
{| class="wikitable" |- ! Type ! Sample ! Sample w/ Replacement |- | Substitution | She will ''write a book''. | ✓ She will ''''do so''''. |- | Substitution | The two boys could ''''order tuna salad sandwiches''''. | ✓ The two boys could ''''do so''''. |- | Question/short answer | ''''What'''' will she ''''do''''? | ✓ ''''Write a book''''. |- | Question/short answer | ''''What'''' could the two boys ''''do''''? | ✓ ''''Order tuna salad sandwiches''''. |}
====Tests for constituenthood of a verb-phrase in X'-grammar==== The ''do so'' construction can be used to test if a verb-phrase is a constituent phrase in X'-grammar by substitution similarly to how other pro-forms can be used to test for noun-phrases, etc.
In X-bar theory, the verb-phrase projects three bar-levels such as this:
<pre> VP / \ ZP X' / \ X' YP | X | head </pre>
With a simple sentence:
<pre> S | VP / \ / \ / \ / \ NP \ / \ \ DP N' V' | | / \ The children / \ / \ V' PP / \ /_\ / \ with gusto V NP | /_\ ate the pizza </pre>
Here again exemplified by Santorini and Kroch, ''do so'' substitution for testing constituent verb phrases in the above sample sentence:<ref name="Syntax of Natural Language"/>
<pre> S | VP / \ / \ / \ / \ NP \ / \ \ DP N' V' | | / \ The children / \ / \ V' PP / \ /_\ / \ with gusto V NP | /_\ did so the pizza </pre>
==Use of ''do'' as main verb== Apart from its uses as an auxiliary, the verb ''do'' (with its inflected forms ''does'', ''did'', ''done'', ''doing'') can be used as an ordinary lexical verb (main verb):
:*'''''Do''' your homework!'' :*''What are you '''doing'''?''
Like other non-auxiliary verbs, ''do'' cannot be directly negated with ''not'' and cannot participate in inversion so it may itself require ''do''-support, with both auxiliary and lexical instances of ''do'' appearing together:
:* ''They '''did'''n't '''do''' the laundry on Sunday.'' (''did'' is the auxiliary, ''do'' is the main verb) :* ''Why '''do''' you '''do''' karate?'' (the first ''do'' is the auxiliary, the second is the main verb) :* ''How '''do''' you '''do'''?'' (a set phrase used as a polite greeting)
==Meaning contribution== In the various cases seen above that require ''do''-support, the auxiliary verb ''do'' makes no apparent contribution to the meaning of the sentence<ref name=TraugottPratt>{{Citation|title=Linguistics for Students of Literature |last1=Traugott |first1=Elizabeth Closs |first2=Mary Louise |last2=Pratt |place=San Diego |publisher=Harcourt Brace Jovanovich |year=1980}}</ref> so it is sometimes called a '''dummy auxiliary'''.<ref name=Huddleston>{{Cite book|last1=Huddleston |first=Rodney D. |author2=Geoffrey K. Pullum |title=A Student's Introduction To English Grammar |publisher=Cambridge U Press |year=2005}}</ref> Historically, however, in Middle English, auxiliary ''do'' apparently had a meaning contribution, serving as a marker of aspect (probably perfective aspect, but in some cases, the meaning may have been imperfective). In Early Modern English, the semantic value was lost, and the usage of forms with ''do'' began to approximate that found today.<ref>I.G. Roberts, ''Verbs and Diachronic Syntax: A Comparative History of English and French'', Springer 1993, p. 282ff.</ref>
==Origins==
Some form of auxiliary "do" occurs in all West Germanic languages except Afrikaans.<ref name=Langer>{{cite book|last=Langer |first=Nils |title=Linguistic Purism in Action: How auxiliary tun was stigmatized in Early New High German |year=2001 |publisher=de Gruyter |isbn=9783110881103 |url=https://books.google.com/books?id=IZUiAAAAQBAJ}}</ref>{{rp|12}} It is generally accepted that the past tense of Germanic weak verbs (in English, -ed) was formed from a combination of the infinitive with a past tense form of "do", as exemplified in Gothic.<ref name=Langer/>{{rp|12}} The origins of the construction in English are debated: some scholars argue it was already present in Old English, but not written due to stigmatization.<ref name=Langer/>{{rp|13}} Scholars disagree whether the construction arose from the use of "do" as a lexical verb in its own right, or whether periphrastic "do" arose from a causative meaning of the verb or vice versa.<ref name=Langer/>{{rp|23}} Examples of auxiliary "do" in Old English writing appear to be limited to its use in a causative sense, which is parallel to the earliest uses in other West Germanic languages.<ref name=Langer/>{{rp|24}}
Some scholars, such as linguist John McWhorter, argue that the construction arose via the influence of Celtic speakers;<ref>{{cite book|last=McWhorter|first=John|authorlink=John McWhorter|title=Our Magnificent Bastard Tongue: The Untold History of English|url=https://archive.org/details/ourmagnificentba00|url-access=registration|year=2009|publisher=Gotham Books|isbn=978-1-59240-494-0|pages=[https://archive.org/details/ourmagnificentba00/page/22 22]–3}}</ref> for instance Welsh uses the verb {{wikt-lang|cy|gwneud}} "to do" to optionally form periphrastic alternatives to inflected verbs (with no difference in meaning).{{cn|date=June 2024}} Others contend that the construction arose as a form of creolization when native speakers addressed foreigners and children.<ref name=Langer/>{{rp|13}}
==See also== {{wiktionary pipe|do#Conjugation|conjugation of do}} *English verbs *English clause syntax *Intensifier
==Notes== {{reflist|group=lower-alpha}}
==References== {{reflist}}
Category:English grammar Category:Word order Category:Syntax Category:Generative syntax