The Auxiliary Verbs "Must", "Need" and "Dare"

Alain Landry
(Terminology Update, Volume 15, Number 6, 1982, page 5)


I. Meaning

"Must" is an auxiliary verb which can express: a) a necessity; b) an insistent demand or a firm resolve; c) the inferred or presumed certainty of a fact; d) prohibition (when used negatively).

a) "Must" expresses necessity and is usually equivalent to "am (is, are) obliged". In the second person, it is used chiefly to express a command, or an insistent request or counsel:

  • John, you must come with me…
  • You must work harder if you want to succeed.

In the third person, it tends to be restricted to the expression of a necessity which is either imposed by the will of the speaker, or relative to some specified end, or enunciated as a general proposition:

  • That must do until we get another one.
  • The books must be produced, as we cannot receive parole evidence of their contents. (OED: Oxford English Dictionary)
  • Most people must work hard to succeed.

That necessity can take the form of a fixed or certain futurity. In this case "must" is equivalent to "fated or certain to":

  • The sewage matter … goes along a sewer which must carry it into the stream, unless it is intercepted on the way. (OED)

Although less emphasized, the idea of necessity is also present in expressions such as "I must say", which means "I cannot help saying", and "you must know or understand" which means "you ought to be informed" or "I find it necessary that you should know or understand":

  • I must beg your indulgence.
  • I must ask you to retract that.

b) In the first person, "must" often expresses an insistent demand or a firm resolve on the part of the speaker:

  • I must, and I will go. (OED)

It is also used in the second and third persons to render sentiments imputed to others:

  • He is not content with a ring and a bracelet, but he must have rings… everywhere. (Wordsworth, OED)

c) Very often "must" expresses the inferred or presumed certainty of a fact, in other words, what Zandvoort calls "an assumption or conclusion",Footnote 1 and what Poutsma calls "Predication of conviction".Footnote 2 "Must" is the auxiliary by which the speaker expresses that "his mental attitude toward the fulfilment of the action or state expressed by the predicate… is one of conviction arrived at by the process of reasoning".Footnote 3 It refers either to the present, and then it is followed by a present infinitive, as in "you must be aware of this", i.e. "I cannot doubt that you are aware of this"; or to the past, and then it is followed by a perfect infinitive, as in "he must have done it", i.e. "It is to be concluded that he did it."

  • He must be seventy now… (Zandvoort)
  • Such a house must belong to some family above the common. (OED)
  • Coleridge must have earned a substantial sum by these lectures. (OED)

Sometimes "must" is used to express an inference which will be rendered necessary if some particular assumption is made:

  • If he says so, it must be true. (OED)
  • If he really did it, he must have been mad. (OED)

d) When used negatively, "must" expresses prohibition. According to the OED, "I must not" can mean "I am not allowed to", "I am obliged not to", etc., or "I will not permit myself to":

  • You mustn’t tell anyone. (Jespersen)
  • I suppose I mustn’t touch the precious papers. (Leslie Keith, OED)
  • I must not sit here talking. (OED)

The adjunction of the negative brings about a considerable shift in the meaning of "must", so that "must not" is not the opposite of "must", but the opposite of "may". The absence of necessity is expressed by "need not". So the opposite of "you may come early tomorrow" will be "you mustn’t come…," whereas the opposite of "you must come early tomorrow" will be "you need not come early tomorrow".

II. Tenses

"Must" is used as a present tense, and, under certain conditions, as a preterite. It is one of a separate group of anomalous verbs which is formed, according to Poutsma, "by the so-called preterite-present verbs, characterized by not having a personal ending in the third person singular of what is now used as a present, viz. can, dare, may, must, shall, will. Except for "dare", they are all of them defective in not having an imperative, nor any of the verbals".Footnote 4 It can also be regarded as one of a small group of verbs, including "need" and "dare", "which have in various ways become partly or completely identical in the two tenses, present and preterite, and which have also to some extent the function as ’auxiliaries’ in common".Footnote 5

Grammarians generally agree that "must" is an old past subjunctive which has gradually been losing its power to point to the past. "It is through the preterite of imagination", says Jespersen, "that ’must’ has become a present tense". The OED seems to agree with Jespersen when it writes: "The use of a present arose from the practice of employing the past subjunctive as a moderate, cautious, or polite substitute for the present indicative."

The use of "must" as a present (or future) does not seem to have caused any concern among grammarians. The same can be said of some of its uses as a preterite. Most grammarians seem to agree with the OED that, in modern use, "must" as a past tense is "confined to instances of oblique narration, and of the virtual oblique narration in which the speaker has in his mind what might have been said or thought at the time." In other words, when the clause containing ’must’ is subordinate either actually or in thought:

  • He could not bear to be idle; he must always be doing something. (OED)
  • It was necessary to make a choice. The government must obtain the aid of the Protestants. (OED)

Jespersen states that "this is practically the only way in which ’must’ can be used as a preterite in modern colloquial speech."Footnote 6

Beside this preterite which Jespersen calls "preterite of indirect speech", there is the "preterite of reality". This is where grammarians do not agree with each other. The OED states that there is one case when "must" can be used as a preterite without being part of a subordinate clause: "As a past or historical present tense, ’must’ is sometimes used satirically or indignantly with reference to some foolish or annoying action or some untoward event."

  • The fool must needs go and quarrel with his only friend. (OED)
  • Just when I was dropping off, a door must bang. (Curme, p. 395)
  • As soon as I had recovered from my illness, what must I do but break my leg! (OED)

But, according to Jespersen and many others before him and after, the sentence of the type just mentioned are not the only ones where "must" is used as a preterite. Jespersen expressly states that "though this dictum of the great authority is, of course, substantially true, some examples of ’must’ to denote a real past time have been collected by Stoffel".Footnote 7 C. Schulze went even farther and stated that the use of "must" as a preterite of reality is "far from being rare or obsolete", that "it occurs much more often than ’was (were) obliged, forced, etc." and is deliberately used to express all shades of the notion of necessity.Footnote 8

Another grammarian, Klapperich, pronounced Schulze’s conclusions to be erroneous, saying that the majority of his examples were "dependent declarative clauses" and that "many of the seemingly independent clauses" contained "a latent oratio obliqua". He suggested that the statement that "must" as a preterite is rare "needs the addition of the qualification: in an independent sentence".Footnote 9 But another grammarian, Klinghardt, saw no reason why "must" should be considered rare even in independent sentences. He firmly stated that he would not find anything strange in such sentences as: "Last night he must again go to bed rather early" thus contradicting Dr. Bradley who had laid down as a principle that to say ’I must go to London yesterday’ would now be "a ludicrous blunder".

In a recent study of this problem, Satoshi Ono, a Japanese linguist, sums up his findings by saying, first, "that in the case where ’must’ means inferred certainty or logical necessity, followed by a perfect infinitive, ’must’ can be regularly used in principal clauses of a conditional complex".Footnote 10 In support of this he brings out one of the examples cited by Schulze:

  • Mr. Greenwood was a short man who must have been good looking when he was young.

and two cited by Gerbert:

  • He must in any case have fought, even had France not forced him to fight by her declaration of war.
  • In such a war, he must have been the captain of the Protestant army.

This is perfectly in line with what is stated in the OED which gives these examples of ’must’ as a past conditional followed by a perfect infinitive:

  • If he had looked, he must have seen the light of the approaching train.
  • Had it (Hamlet) been in existence… before 1598, it must have been mentioned by Meres.

Mr. Ono’s second conclusion is that "must" is "regularly used in that-clauses",Footnote 11 and that in some cases "it is even used in adjective and adverbial clauses, including elliptical ones":

  • She worked when she could and starved when she must. (Dickens)
  • We submitted because we must. (Jespersen)

His third conclusion is that" ’must’ is likely to be used as a preterite in a principal clause, when it is followed or preceeded by ’needs’, ’necessarily’, or ’of necessity’ probably influenced by such words. This form can be found in the Bible and many modern writers". And he adds: "This ’must’, as is the case with other usages of this word, is not used objectively or dispassionately, but subjectively and so emphatically, probably because it originates from the past subjunctive".Footnote 12 Among the examples that he gives are the following:

  • And he must needs go through Samaria. (John, IV, 4)
  • So the anxious, heart-stricken Adam must of necessity, wait and try to rest till eleven o’clock, when the coach started. (Eliot, Adam Bede, p. 38)
  • A commander like Mansfield, who could not pay his soldiers, must of necessity plunder wherever he was. As soon as his men had eaten up one part of the country, they must go to another, if they were not to die of starvation. (Gardiner, Thirty Years’ War, p. 147)

Mr. Ono’s fourth conclusion is that "must", apart from the cases where it is used in oblique narration or as a historical present tense, does occur, though not very often. His examples are the following:

  • Warmth he found in the toils of the chance… but for decoration he must have clothes. (Carlyle, Sartor Resartus, p. 26)
  • My mouth was so dry, I must wet it with seawater before I was able to shout. (Stevenson, Kidnapped, p. 14)
  • On the morning, however, it was rainy, and every one must stay indoors. (Eliot, Clerical Life, p. 124)

Most of these examples are the same as those found in Jespersen’s A Modern English Grammar, Part IV, p. 7.

To summarize all this, we could say that "must" as a preterite occurs, not in completely independent sentences, but in sentences with given situations, i.e. usually in clauses subordinate not only in form but in sense. The problem then remains to determine whether sentences including "must" are completely independent sentences, or sentences where the verb is subordinate in thought to a verb in past time, or sentences in the virtual oblique narration, showing not a fact, but the speaker’s thought or soliloquy. In many cases it is almost impossible to determine in which sense the writer or speaker has used the expression. This may explain to a certain extent the differences of opinion among grammarians as to this or that particular example. So one can easily imagine that the problem of the preterite use of ’must’ will be something of an inexhaustible source of discussion, unless some grammarians find an adequate theory of the modal auxiliary verbs which will provide a means of settling a problem that seems insoluble on the level of discourse.


"Need" according to all dictionaries is a verb that means "have need of, want, require" and is conjugated as all full verbs normally are: "He needs money; do you need anything else?" But apart from this, it also has the meaning of "to be under a necessity or obligation to do something". When used in this sense, it often shows some peculiarities by which verbs are recognized as auxiliaries in English:

  1. It can take the infinitive without "to":
    Need they come with us?
  2. It can contract with the negative "not":
    You needn’t come with us.
  3. It can have a defective inflexion:
    He need make no protest.

These facts should suffice to place "need" unmistakably among the auxiliaries. However, "need" is peculiar in that it also has parallel non-auxiliary uses:

  • He needs to come with us.
  • They do not need to hurry.

This raises the problem of a possible difference of meaning between the two forms. Here is how Dwight L. Bolinger, in an article published in Vol. 4 of College English, approaches the problem:

Comparing the two (uses) we find another condition for auxiliary use satisfied—that expressed by the Merriam-Webster as "usually with some loss of its own original signification". The non-auxiliary "He needs to see the doctor" suggests a requirement close to the literal meaning of "need"; "Need we see the doctor?" suggests a more indefinite compulsion. Make the two phrases in all other respects identical, and the contrast is clear. "Does he need to see the doctor now?" implies a need for medical attention; "need he see the doctor now?" may imply "if he is to see him at all", or a number of other notions, but always something different from the inflected, non-auxiliary "does need", and tending toward the idea of external constraint rather than that of literal requirement or expression of lack within one’s self. The non-auxiliary calls for the fulfilment of a personal need, the auxiliary for compliance with something external.Footnote 13

The Thorndike-Barnhart Comprehensive Desk Dictionary solves the problem in a completely different manner. According to this dictionary the difference between the two uses would simply be one of level of formality: "Note that ’need’ with the meaning of "must", "should", "have to" in rather formal usage is used as an auxiliary—that is, like "must" and "should" it has the third person singular form "need" (rather than ’needs’), it takes an infinitive without "to", and in negative and interrogative constructions is used as the main verb, not as an infinitive with ’do, does’. Examples of typical use are:

  1. Interrogative
    • (Formal) Need she go?
    • (Informal) Does she need to go?
  2. Negative
    • (Formal) She need not go.
    • (Informal) She does not need to go.
  3. Affirmative
    • (Formal) She wonders if she need go.
    • (Informal) She wonders if she needs to go.

I. Auxiliary-use of "need"

According to Bolinger, "need" is used in the following types of sentences, "the third of which", he states, "Curme misses".Footnote 14

  1. Statements in which the need is negatived (with "need not", "need never", "need no" plus adverb or noun, "needn’t")
    • She need not (needn’t) hurry.
    • There need never come a time like that.
    • He need no more reply than make an outright confession.
    • There need be no doubt in your mind.
  2. Questions expecting a negative answer:
    • Need he show unfriendliness?
    • We ask whether money need absorb his attention.
    • Need there be more than ten?
  3. Statements containing minimizing adverbs such as: barely, hardly, only, but, scarcely, seldom, solely, rarely:
    • It need seldom be required of them.
    • He need scarcely expect more than that.
    • She need look at the picture only if she wants to.

This seems to be in accordance with the OED, where it is considered that "need" is an auxiliary "when the clause has the forms ’it (she, I, etc.) Need not’, ’(why) need (it, etc.)’ or is virtually equivalent to one of these". What Bolinger achieves with his third category merely comes down to determining what can be considered "virtually equivalent" to the negative use of "need". It is not likely that Curme, who, according to Bolinger, "has dealt rather fully with the question", misses anything here. He probably considered that minimizing adverbs could be regarded as, in a way, equivalent to negations. This is exactly what Poutsma does when he includes negative contexts "such as imply a negative, although containing no negative word".Footnote 15

II. "Need" as a preterite

Although all the examples given above are in the present indicative, "need" can also be used with all the characteristics of an auxiliary in the preterite indicative and the preterite conditional. And then, just like "must", it will have the same form for the preterite as for the present.

This is especially the rule in the preterite indicative in subordinate clauses, especially subordinate statements, in negative contexts:

  • It was hinted that perhaps they need not always make so much smoke. (Dickens)
  • She was told that she need not take the trouble. (W.B. Maxwell)
  • She was so well that nobody need be uncomfortable about her. (Dickens)

In many cases the principal sentence is merely understood:

  • He need say no more this evening, and risk giving himself away. (Galsworthy)

Exceptions, however, are not unfrequent:

  • She saw that she needed not to fear me. (Blackmore)
  • They promised with the eyes what they needed not to promise with the tongue. (A. Hope)

"Need" is also used in principal sentences, but according to Poutsma, "is usual only when another verb shows the time sphere, but ’needed not’ is in ordinary language replaced by ’did not need’".Footnote 16

  • I had no less than five several morning dresses, so that I need never be seen twice in the same dress. (Fielding)
  • Mr. Weston need not spend a single evening in the year alone if he did not like it. (Jane Austen)

"Need" is also practically used regularly, in negative context, in the preterite conditional followed by a perfect infinitive:

  • You needn’t have been so sharp. (Dickens)
  • You need not have told me that. (Flor. Marryat)


"Dare" is another verb that can be used with all the characteristics of an auxiliary, when it means "to have boldness or courage (to do something)", "to be so bold as". It is often followed by an infinitive without "to":

  • No priest dares hint at a Providence which does not respect English utility. (Emerson)

It can contract with the negative:

  • You daren’t ask for a raise for fear of losing your job. (Zandvoort)

It can have a defective inflexion:

  • She dare not tell her choose. (B. Shaw)

It does not always require "to do" in interrogative sentences:

  • How dare you come here? (Zandvoort)

There seems to be a large variety in the usage of "dare". This is made obvious in the OED where we read: "The original third person singular ’he dare’ and past tense ’durst’, remained undisturbed to the modern period, in which the transitive senses were developed; but early in the 16th Century, the new forms ’dares’ and ’dared’ appeared in the south, and are always used in the transitive sense, and now also in the intransitive sense when followed by ’to’. In the original construction, followed by the infinitive without ’to’, ’dare’ and ’durst’ are still in common use (especially in the negative ’he dare not’, ’he durst not’); and most writers prefer ’he dare go’ or ’he dares to go’ to ’he dares go’. The northern dialects generally retain ’he dare, he durst’, and writers of northern extraction favour their retention in literary English when followed by the simple infinitive without ’to’".

Jespersen does not agree with the OED as to the use of "durst" which, according to him, has become obsolete".Footnote 17 Zandvoort also seems to consider this form obsolete since he does not even mention it in his Handbook of English Grammar. However he agrees that usage varies considerably in the use of "dare". Few of the rules he mentions in his book are presented as the only correct usage. He expressly states that "as to the use or absence of "to do", with "to dare" there are three possible constructions in negative sentences with ’not’: He dare(d) not return; He does (did) not dare to return; he does (did) not dare return".Footnote 18 Speaking of the infinitive after "dare" when "dare" is preceded by an auxiliary, the most he can state is that "the infinitive is more commonly used with "to" than without".Footnote 19 The only strict rules that can be found regarding "dare" are the one where Zandvoort expressly states that "after the present and the past tense of ’to dare’, the plain infinitive is always used in interrogative sentences and in negative sentences with enclitic ’not’ that are formed without the auxiliary ’to do’Footnote 20 and the one where he says that after "daring" the infinitive is always used with "to".21

("Daring", though, cannot be used in the progressive form because it is an auxiliary like "must", "can". Zandvoort probably refers here to the "full" verb "to dare"!)

  • How dare you speak to me like that?
  • He dared not return to the house.
  • (She shook her head, not daring to speak.)

Another thing which must be mentioned in connection with "dare" is what the OED calls the "careless use" of the present "dare" for the past "dared". This anomalous use of "dare" is mentioned by Zandvoort and Jespersen and appears to be confined to the negative. "’Dare not’", says Zandvoort, "is usually pronounced [de[de:ant], and sometimes written without the second ’d’, when the time-sphere is sufficiently clear from the context".22 He gives the following examples:

  • He was in such a temper that I daren’t ask questions.
  • He would have liked to protest, but he dare not.

Jespersen adds examples without a following "not" which, he says, "are less frequent, but nowadays not at all rare".23

  • When the dogs came bounding up, to welcome her, she dare hardly touch them.

To this Jespersen adds a mention of the imaginative use of "daren’t" as equivalent to "daredn’t":

  • You know you daren’t have given the order if you hadn’t seen us.


CURME, George O., Parts of Speech and Accidence, D.C. Health and Company, Boston, 1935.

JESPERSEN, Otto, A Modern English Grammar, Part IV, GeorgeAllen and Unwin Ltd, London, 1949.

POUTSMA, H., A Grammar of Late Modern English, Part II: The Parts of Speech, Ed. p. Noorhoff, Groningen, 1926.

ZANDVOORT, R.W., A Handbook of English Grammar, Longmans, 1962.

Studies in English Grammar and Linguistics, A Miscellany in Honour of Takanobu Otsuka, Tokyo, 1958.


American Speech, Vol. 30, 1955. Crowell, F.L., ’Predating "have to", "must"?’ pp. 68-69.

College English (Chicago-Champaign) Vol. 4, 1942-43, Bolinger D.L., "Need: auxiliary", pp. 62-5.

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