MODAL VERBS

Generalities

A distinction can be drawn between the senses of modal verbs and the type of speech

acts in which they may participate. Thus, in their basic sense, they may occur in direct speech

acts as statements, questions, negation of possibilities, probabilities, permission etc. In

sentences with epistemic modals, the indirect illocution expresses the confidence of the

speaker that the proposition is possible, probable, certain etc. So, in this case the speaker is

the source and at the same time, the person spoken to (or the addressee). He must be in his

office by now. There must be some mistake.

Modality may range from possibility to absolute certainty. This fact suggests the

difficulty that we encounter when we try to establish a rigorous hierarchical model – with the

exception of, perhaps, basic volumes.

In order to illustrate some of the general characteristics of epistemical modality, we

may take as an example one verb in its epistemic use, for instance must. In connection with

the factor time, the epistemic use of must indicates a great variety concerning the conditions

imposed on the genericity of the complement. It can embed stative verbs. Bill must be tall,

because I heard his girl-friend has to wear high-heeled shoes when she goes out with him.

Here, must reports a conclusion based on inductive evidence. In John must be easy to talk

to, the subject of “talk to” is indefinite; what is indicated is that anybody can easily talk to

John and, as a logical conclusion the addressee can also prevail himself the advantage.

However, John must be easy for you to talk to is not a paraphrase of John must be easy to

talk to. John must be easy for you to talk to states a completely different deduction on the

speaker’s part, which is based on the fact that he, the speaker, knows that the addressee has

already talked to John. Thus must, in John must be easy to talk to makes a reference to the

present or the future, and must in John must be easy for you to talk to makes a reference to

the past. So the complement of must in this last sentence is generic, which means that the

sentence describes something in an atemporal sense, whereas a sentence such as John should

be easy to talk to describes something we expect to be true in the future.

The epistemic use of must may also be formalized as an obligation that has as subject

the speaker’s thoughts. The cause is not expressed in the sentence with must but in a

secondary sentence: John must have gone since I don’t see his coat anymore. Parallelly, we

can show that John must have left is less exact than John has left.

Generally the epistemic must (“John must have left”) is used in circumstances in

which John’s leaving is not certainty. Uttering John must have left the speaker marks the fact

he has no direct knowledge about John’s leaving and neither was he told about it from a

reliable source. It seems that John must have left indicating that John has left follows

logically from other facts known by the speaker and also for reasoning that he is eager to

entertain. If anyone has seen John leaving he will no utter John must have left because he

will be in a position of uttering John has left.

Possibility: CAN, MAY, COULD, MIGHT

An event associated with the Modal System is represented as, in the loosest sense of

term, a possibility. If we take such a sentence as If he left yesterday, he ------ arrive today,

and place MAY or CAN in the black, the result is a cautious rather than a confident

statement, and one can imagine that the speaker would not be particularly surprised if the

event did not occur. Its occurrence is less than likely.

CAN admits only that occurrence is a possibility. With MAY, however, the situation

is different; MAY suggests that the speaker takes the possibility for granted and is willing,

further, to speculate on its probability.

The multiplicity of observable semantic variations is no doubt limited only by the

perseverance of the observer. Those examined here will be restricted to two contexts: that

embodying the approval of the speaker, and that embodying some unlikelihood to be played

against the likelihood of modals.

The first context – approval of the event by the speaker – provides a contextual

variant with the semantic meaning “recommendation”, as in: You must go to that movie. It’s

very good. You should go to that movie. It’s very good. The mechanism of the influence of

the context seems to be that a statement is made that an event is likely to occur in order to

persuade someone to make it occur.

With CAN, with its meaning of more possibility can be roughly paraphrased by the use of the

adverb sometimes: Even expert driver can make mistake = Even expert drivers

sometimes make mistakes.

CAN may express both present and future possibility. In this case, CAN is used to

suggest that perhaps something may be. It is replaceable by MAY, and many English

speakers would prefer MAY instead CAN (except in questions): He can be home now. He

can be riding. He may be riding. Only in this case of CAN may reference to the past be

made by CAN HAVE: He can have been riding. The meaning of past possibility, however,

is more usually expressed by COULD followed by a PERFECT INFINITIVE. But past

possibility expressed by COULD followed by a Perfect Infinitive is of a slightly smaller

degree than that expressed by CAN and a Perfect Infinitive. The following example suggests

this slight difference: Darling, do stop worrying about Aunt Helen. I’m sure nothing had

happened to her. She is so absent minded that she could easily have forgotten that we’ve

invited her for the weekend.

On the other hand COULD, followed by a simple Infinitive expresses a smaller degree

of present-future possibility that that expressed by CAN. The only case when CAN, in this

sense, is not replaceable by MAY, is in questions: Can he be riding? but not * May he be

riding? In the sense of possibility, MAY is used with reference to both present and future

time. Only where it refers to the present is it usually replaceable by CAN (commonly only in

questions).

Yet MAY in this case is not used in questions (CAN or MIGHT being used instead).

MIGHT is used in a tentative sense or for habitual past; the past time analogue is MAY

HAVE: He may come. He can be there now. He may be there now. but not He can come,

nor * May he be there now? but He might come. He may have come yesterday. So, we may

say that MAY expresses present and future possibility, as in: I think we ought to take

raincoats with us. It may rain. (“Perhaps it will rain”); and also, when followed by a Perfect

Infinitive, past possibility: He may have finished his work by now. I’ll go and see (“There is

a possibility that he has finished his work since I last visited him”).

MIGHT, followed by a simple Infinitive expresses a smaller degree of future

possibility that the expressed by MAY. MIGHT, followed by a simple Infinitive expresses

the past form of this smaller degree of possibility. The possible MAY-MIGHT frequently

co-occurs with the adverb possible which has an effect on intensification.

As it was demonstrated earlier, there is a difference of meaning between CAN and

MAY. Besides, what have been said before, there is an opinion that the difference between

them parallels a difference of grammatical construction following „It is possible”, as the

following relations of synonymy show: This illness can be dangerous is synonymous with It

is possible for this illness to be dangerous. This illness may be dangerous is synonymous

with It is possible that this illness is/will be dangerous.

It is difficult to explain what difference of meaning is involved here. All that can be

said is that the first pair of sentence, the notion of possibility is general and theoretical; but in

the second pair, it is more particular and practical kind of possibility, often in the future. The

second pair of sentences seems to have a slightly stronger meaning: The pound can be

devalued. This is nerely a statement which everyone knows to be true: that it is possible for

currencies to be devalued, and that the pound is no exception. But The pound may be

devalued is much more threatening statement, suggesting that the devaluation of the pound,

as a practical course of action, is now under consideration.

If any logical differences do enter into the “theoretical”/ “practical” opposition, it is

that the “stronger” meaning implies the “weaker”: The pound may be devalued implies The

pound can be devalued. However the difference is subtle enough to make intuition uncertain

and only a tentative formulation will be suggested.

There is a synonymy of active and passive construction when CAN is used with the

force of possibility: Waste can ruin a country’s economy is synonymous with A country’s

economy can be ruined by waste. But there is no such equivalence with BE ABLE TO

which replaces CAN when used in the sense of ability. If we understand an active sentence in

the sense of ability the corresponding passive sentence has to be understood in the possibility

sense: He can (=is able to) beat the world champion. The world champion can be beaten by

him. On the other hand, these differences should not disguise the very close connection of

meaning, which is one of implication: He is able to speak five languages implies It is

possible for him to speak five languages.

With CAN in the sense of possibility, we may speak of certain degrees of possibility.

First, there is a possibility conditioned by circumstances: I can give you a lift if you want.

Second, there is lack of trust in a possibility in negative and interrogative constructions: You

cannot have been there at that time. Can this be true? And finally, doubt or astonishment at

the idea of possibility is strongly emphasized interrogative and exclamative constructions:

How could you be so selfish? It really can’t be so late!

Probability: WILL, MAY, MIGHT

WILL is used to indicate that something probably is happening. In this sense it may

occur with adverbials of present time. The most important characteristic of this use is that its

past time analogue is WILL HAVE. This use usually occurs only in progressive forms,

except in the case of non-progressive verbs. That is to say, it usually refers to activity or

states continuing at the present moment.

MAY and MIGHT are also used in the sense of probability: He may leave tomorrow.

He might leave tomorrow. The difference in meaning is observable in the fact that MIGHT,

here, is associated with some additional remark suggesting conditions or difficulties that

reduce the likelihood of the event.

Supposition: WILL, CANNOT, MUST

A supposition about something in the present can be expressed, in the second and

third persons only, with an unemphasized WILL: It’s Monday. If she has kept to her

programme, she will be home now. (“I suppose that she is home now”) Supposition about

the future cannot easily be expressed in the same way. Since an unemphasized WILL in the

second and third persons usually expresses general futurity, the idiom of supposition is

difficult to recognize. A supposition about something in the past can be expressed, in the

second and third persons, with an unemphasized WILL followed by a Perfect Infinitive: It’s

Monday. If she has kept to her programme, she will have been home yesterday.

The negative form of CAN also may express present supposition or deduction: For

heaven’s sake, it’s only ten o’clock! They can’t be in bed yet. Ring the bell again.

Deduction and supposition about something in the present (but not in the future) can be

expressed by MUST.

I don’t think they will be at home. It is such a lovely day that they must be in the country

somewhere. (“I suppose, because the day is so lovely, that they are out somewhere in the

country”). The negative of this construction is not MUST NOT: it is CANNOT (or CAN’T)

(with the same meaning as described before): I heard that there it is always very cold in

winter. It cannot be a very pleasant place to live in. (“I suppose that it is not a pleasant

place to live in”).

Deduction and supposition about something in the past can be expressed by MUST

followed by a Perfect Infinitive. He looked quite unhappy when I last saw him. He must

have suffered terribly. (“I suppose that he suffered terribly”). The negative of this past

construction is either CANNOT or COULD NOT (or contraction) followed by a Perfect

Infinitive: I heard that it was terrible weather in May! What a shame! It can’t (couldn’t)

have been as successful trip as you had hoped for. (“I suppose it was not”).

Logical necessity: MUST, SHOULD, HAVE TO, OUGHT TO, NEED,

NEEDN’T

Going back to the problem of semantic variation discussed in Generalities and

more precisely, to the two contexts mentioned in connection with this problem, in the second

context, that of unlikelihood, semantic meanings are produced that may be glossed as

”necessity” or “obligation”.

The unlikelihood of the event may arise out of any of a number of considerations, the

most prominent of which, perhaps, is the disapproval of unwillingness of the potential

performer of the event. A statement that an event is likely to take place, in the face of the

unknown unwillingness of its performer, suggests, that he has to do it, whether he wants to or

not. Hence: She’d like to read but she can’t; she must finish her homework. I really should

finish my homework. This semantic meaning is produced only with MUST and SHOULD,

which play their meaning of a high degree of likelihood against the unlikelihood of the

context.

The uses of MUST and HAVE TO, connected with the meaning of logical necessity

convey the certainty of logical inference. For example, the following rational process may be

supposed to lie behind the remark That must be my brother said by a man who has heard the

telephone ring: “My brother said he would phone at this time – I have just heard the phone –

therefore, my brother is phoning now”.

MUST and HAVE TO are not used of facts known by direct observation, but

of these known by logical assumption. This factor of indirect knowledge has the effect of

weakening the meaning of necessity, in certain conversational contexts, to what is effectively

an expression of uncertainty: You must be tired. We may speak also about an ironic

weakening of MUST in the sentence like: If you must drink, please use a glass. One might

interpret this reading the speaker’s thoughts: “If it is necessary for you to drink (but of course

drinking isn’t a necessity, it is nerely a vice which you could break if you want to)…” MUST

in such a context could easily be replaced by WILL in the sense of intention.

OUGHT TO may also be used to express necessity but there is a difference

between the meanings of OUGHT TO and MUST in this respect. We may contrast the

following examples: That must be her daughter. That ought to be her daughter. They must

have finished their work by now. They ought to have finished their work by now. The first

sentence of each pair the speaker commits himself to the certainty of the proposition; but in

the second sentence, he is not sure. MUST here conveys the necessity of logical inference.

OUGHT TO conveys the necessity given the premise, of the conclusion, but doubt about the

conclusion is based. In other words OUGHT TO leaves open the possibility of non-action,

while MUST does not. We may thus attest: He ought to go, but he won’t but not * He must

go, but he won’t. A contrast exists also between the meanings of MUST and HAVE in the

realm of necessity: Someone has to be telling lies, is synonymous with “It is impossible for

everyone to be telling the truth”. The former indicates a theoretical meaning and the latter a

practical necessity- but in this case, the theoretical meaning seems to be stronger There has to

be a way out adds a note of desperation or determination to There must be a way out: the

speaker refuses even to contemplate any other possibility.

As in the case of CAN and MAY in the field of possibility, the contrast between

HAVE TO and MUST in the field of necessity is not such as to make any great difference or

true value. The stronger meaning implies the weaker in each case: Someone has to be telling

lies implies Someone must be telling lies.

MUST expresses what can be described as an unexpected necessity, while HAVE TO

expresses a known necessity i.e. a necessity that the speaker has not just suddenly realized:

Nearly seven o’clock already! I must leave for school. I have to be there at eight. The

tendency nowadays, however is to prefer MUST to HAVE TO, even for known necessity.

As a special verb expressing necessity, NEED can be followed either by an infinitive

without “to” or by an infinitive with “to”. When it is followed by an infinitive without “to”, it

has the following peculiarities:

(a) It cannot be used in the affirmative – only in the negative and interrogative;

and in the negative and interrogative it is not conjugated with the verb DO.

(b) In the third person singular, NEED is not inflected.

(c) It has no other tenses, no other forms, no infinitives, no participles, and no

gerunds.

(d) It creates a present or future meaning when it is followed by a simple

Infinitive and a past meaning when it is followed by a Perfect Infinitive: Need

he do it now? She need not go there tomorrow. Need Peter have done it

yesterday? Mary need not have gone there yesterday. In the last two

examples, it is understood (1) that Peter did do it yesterday, and (2) that Mary

did go there yesterday.

When it is followed by an Infinitive with “to”:

(a) It has all tenses, forms, infinitives, participles, gerunds – and it can be used

in the affirmative as well as the negative and interrogative.

(b) It is inflected in the third person singular of its present tense.

(c) In the negative and interrogative form of its present and past tenses, it must

be conjugated with “do”, “does” or “did”.

NEEDN’T may be interpreted in terms of necessity when used in a context such as:

You needn’t bother about that.

Certainty: MUST, CANNOT

Conclusion or near certainty is expressed by MUST. It is not used in this sense with

future reference. In the past time, the analogous form is MUST HAVE and in the negative

CAN’T: There must be a hundred people there. He must be mad to do that. There must

have been a hundred people there. There can’t be a hundred people there.

When producing speech acts indicating permission or obligation, the attitude of the

speaker may be one of identification or association with the expressed modality. For volition,

desire, intention we must also take into consideration the phonological state which may be

marked as surprise, modesty, anger etc. The modal system presents systematic relations

between the same semantic concept.

When speaking about epistemic modality, we mentioned that modality may range

form possibility to absolute certainty. A similar phenomenon occurs in the case of deontic

modality, where modality may range from permission to obligation. With their deontic sense

the modals often participate in indirect speech acts whose illocutionary force differs form the

direct speech act suggested in the surface structure.

The modals can be used performatively and non-performatively. In some sentences

with deontic modals the speaker is associated with the origin of the source of the volitional

act and the person spoken to (or the addressee) with the aim or destination of the intention,

i.e. the speaker is the initiator of the permission and obligation: You must stay, I still need

you; You must be home by ten o’clock; You must go now or you’ll be late. Consistent with

the principle that the speaker is also the authority, the last sentence renders the idea of self-

obligation; the speaker exercises his power on himself, probably out of a sense of duty, or

self-discipline. In this case modals are used performatively.

In other sentences with deontic modals the source of permission or obligation is not

the speaker but an external authority. The speaker only reports the existence of the

obligation, so the modals do not have a performative value: You must leave now; otherwise

you’ll miss the plane.

Willingness: WILL, SHALL, WOULD, CAN

Willingness denotes a yielding to someone else’s will. WILL is only synonymous

with “be willing” if the subject of WILL and the implicit subject of the following non-finite

verb are the same: He will tell you the whole story. (“He is willing…”)

SHALL may also be used in the sense of willingness but there is a difference of

meaning between SHALL and WILL in this report. This difference is made clear by the

following paraphrases: My chauffeur will help you (=”My chauffeur is willing to help you”).

My chauffeur shall help you (=“I am willing for my chauffeur to help you”). With WILL,

the subject of the auxiliary (i.e. the person who is willing) is also the notional subject of the

main verb (as mentioned before); but with SHALL, it is the speaker who is the willing or

insisting party.

The use of WILL with the meaning of willingness is common, especially in second-

person requests: Who will lend me a cigarette? (“Who is willing…?”).WILL is normally

unstressed, and can be abbreviated to ‘ll.

On the contrary, SHALL so used is rare. This is probably so an account of the

unpleasant connotation on condescension it bears. The implication is that the speaker is

conferring a favor: Dear child, you shall have your doll when we get home. (“I am willing

for you to have your doll”). When willingness must be suggested in first-person expressions,

the verb that is used is WILL and not SHALL that is normally used in first-person

expressions. This special use of the verb is what conveys the special meaning required. Used

so, WILL refers to both the present and the future: Well, if you promise to pay it back in the

first few days of next month, I will lend you the money that you need. In expressions of

second and third person willingness, the idiom is recognizable only when it refers to the

present; in the future there would be nothing to distinguish it form and ordinary expression of

general futurity: He says he will read the book tomorrow. There is nothing to show that this

sentence is not an expression of general futurity.

WOULD is needed in the first person in reported speech if WILL was used to

express a special meaning: I said I would lend you the money you want (i.e. from the

expression of willingness “I will lend you etc.”).

Another verb that can be used to express the meaning of willingness is CAN and its

use is very similar to that of WILL. In this case, CAN always refers to the future and can be

collocated with future time adverbials. That’s why it can be used instead of WILL when a

future expression of willingness is needed (because WILL, as it was mentioned earlier,

cannot express a clear future willingness): Can you help me tomorrow? (= “Are you willing

to help me tomorrow?”) I can do that for you. (= “I am willing to do that for you”)

Volition: WILL, WOULD, SHALL

The semantic meanings of WILL and WOULD that are produced as contextual

variants of the syntactic meaning “hypothetical” may be glossed as volition on the part of the

performer in the context of unlikelihood. The meaning of volition is seen in: We warned him

not to bring charges, but he would do so. In this example, the unlikelihood of the event lies

in the preference of other parties concerned for other course of action, statements of this kind

are typically complaints.

When WILL is used with sense of volition, it usually refers to the future. WILL used

in this is sense different from WILL that is used to express more futurity by fact that that it

does occur in conditional clauses. This use of WILL is very common, at least with all verbs

that refer to activities that may be willed or agreed. With verbs of this kind plain future

reference is more likely to be made by going to or by the use of non-modal progressive,

while the use of WILL, especially in questions, suggests volition: will you read a paper

tomorrow?

SHALL may also be used to express volition. First person questions with SHALL

consult the will of the listener. Instead of declaring the will of the speaker: Shall I open a

window? (= “Is it your will that I should…”) Shall we go to the theater this evening? (= “Is

it your will that we should…”). Yet often the meaning of a question form does not seem to

correspond exactly with the volitional meaning of the statement form. The lack of fit is

particularly prominent with questions which are offers of help: Shall I help you with your

luggage? Where the meaning is the neutral volition: “Do you want me to…” rather than “Is it

your will that…”

Volitional SHALL is very rarely found in questions with second-person or third-

person subject, but it seems at least a possibility in sentences like: Shall Virginia do your

shopping for you? (= “Do you want…?”) in which (say) a mother offers her daughter’s help

to a third party.

Intention: WILL, SHALL

The concept of intention may be placed somewhere between the concepts of

willingness and insistence: I will celebrate this very night (= “I have the intention to

celebrate”). Occurring mainly with first-person subjects, WILL in this sense conveys,

according to the context, a promise, a threat, or corporate decision. This WILL is

generally connected to ‘ll.

SHALL also expresses intention on the part of the speaker: I shall write tomorrow.

With this meaning, SHALL occurs exclusively with first-person subject. When it expresses

intention, SHALL becomes interchangeable with WILL.

Promise: SHALL, SHOULD

The verb that is most commonly used to express the meaning of promise is SHALL.

This use of SHALL covers a variety of meaning but may be formally established by the fact

that SHALL cannot, in this use, be replaced by WILL, and that it may occur in conditionals:

You shall have it tomorrow; He shall do it; If he shall do it, … These sentences are also

examples of the variety of meaning covered by this use of SHALL. The first is a promise to

act and the second is a promise to enforce action. But what is, perhaps, common to both of

them is that the initiator of the activity is always external to the subject. If we take such an

example as: You/he/they shall be paid handsomely whose meaning is “I promise a

handsome payment for you (him, them)”, we can notice that the idiomatic expression of

promise is clearly recognizable here by the peculiar use of SHALL in the second and third

persons; any additional statement such as “… and I promise it”, or “… and I give you my

word for it” is therefore unnecessary.

A promise in the first-person could be expressed idiomatically by the use of WILL

instead of SHALL: I will pay you (him, them) handsomely but this use would lead to

ambiguity, i.e. WILL in the example above could equally mean that the speaker is willing to

pay you (him, them) handsomely; and this is not the same as a promise to give a handsome

payment. That’s why it’s better to avoid the use of WILL in this sense and to stick to our first

statement, namely that SHALL, when used to express promise, cannot be replaced by

WILL.

In the second and third persons in reported speech, SHOULD is needed to

express the special meaning of promise: I said (that) you should have and increase in

salary on the first of January. (i.e. from the idiomatic promise: I said: “You shall have an

increase in salary etc…”)

Insistence: WILL, SHALL

WILL may express insistence only if the subject of WILL and the implicit subject of

following non-finite verb are the same (as in the case of WILL used to express willingness):

He will go swimming in dangerous waters (= “He insists on going swimming.”). This

meaning of WILL is not very common, possibly because of the strong emotional overtones

accompanying the idea of insistence. With second and third person subjects, the feeling of

exasperation at someone else’s obstinacy is uppermost; with a first-person subject, the

speaker makes his own uncompromising determination felt, with a force the verbal equivalent

of banging one’s fist on the table. In no circumstance can a sentence containing WILL with

the meaning of insistence be emotionally neutral. WILL in this sense is always stressed and

cannot be contracted to ‘ll.

SHALL may also express insistence: You shall obey my orders! (= “I insist that you

obey…”). This meaning is of very restricted use, and carries strong overtones of

imperiousness. Besides, this use of SHALL is undemocratic in suggesting that the listener’s

will is entirely subservient to that of the speaker. The difference between WILL and SHALL

in the sense of insistence is made clear by the following paraphrases: I will marry her. (= “I

insist on marrying her.”) No one shall stop me. (= “I insist that no one stop me.”). With

WILL, the subject of the auxiliary (i.e. the person who insists) is also the notional subject of

the main verb (as shown before); but with SHALL, it is the speaker who is willing or

insisting party.

Permission: MAY, MIGHT, CAN, COULD

The meaning of permission is generally expressed by MAY. In colloquial

English, MAY characteristically signals permission given by the speaker: You may

smoke in this room. (i.e. “You are permitted (by me) to smoke in this room.”). In

more formal contexts, however, the meaning is not limited to this but is extended

permission without respect to who does the permitting. In formal English, MAY

replaces CAN which is often considered less polite and less correct than MAY.

In questions and if clauses, MAY typically indicates permission given not by

speaker, but by the person questioned: May I smoke? This means “Will you allow me

to smoke?” rather than “Will I permit myself to smoke?” which is a pretty odd

question to ask. If we take a sentence such as: You may go, Jones. (spoken, typically,

by a schoolmaster in an old fashioned schoolboy story), this is and instance of the

strengthened, almost imperative use of MAY. The suggestion is that so great is

speaker’s authority that nerely for him to grant permission for something is guarantee

of its instant execution.

When MAY is used to give permission, reference may be to the Present or

Future time. There is not past time analogue. MIGHT is used as the analogous

tentative form only in request-questions: You may go. You may come tomorrow. May

I come in? Might I come in? but not * You might go. But there is a situation when

MIGHT may be used to express permission, namely for the typical products of

understatement-irony, sarcasm and the like: Well, if you really have nothing else to

do, you might do your homework. Also, MIGHT is used in Reported Speech: She

said I might go out to play when I had finished my homework.

Another verb that is used to express permission is CAN. CAN is more widely

used than MAY as an auxiliary of permission in colloquial English, having the less

specific meaning “You have permission” rather than “I give you permission”. You

can smoke in this room means simply “the rules allow it”.

One can easily imagine the following conversational exchange with CAN, but

not with MAY:

Mr. X: “Can I smoke in here?”

Mr. Y: “So far as I know you can – there’s no notice to the contrary”

On the other hand, CAN tends to be avoided in formal and polite usage (in

both written and spoken English) because MAY is felt to be the more respectable

form and it may carry the connotation of superior social status of the granter of the

permission.

In colloquial speech, the difference between CAN and MAY is unimportant

enough to be ignored in most cases.

An ironic extension of CAN in the sense of permission may be detected in

sentences such as: If you don’t like it you can lump it; you can forget about your

holiday. Such utterance are disparaging in tone and have a stronger import than

expected with CAN; instead of merely permitted a course of action, they strongly

recommend it. Perhaps, however, we may still treat these as instances of the

permissive meaning of CAN, by reading them as sarcastic offers of leave for the

listener to do something that he knows he cannot avoid. CAN may refer to the future:

He can come tomorrow. Past permission is expressed by COULD: We could have

had breakfast in bed in that pension whenever we liked. (i.e. “We were permitted to

have breakfast in bed whenever we liked”). COULD when followed by a Perfect

Infinitive also expresses past permission: We could have had breakfast in bed if we’d

liked. (i.e. “We were permitted to have it in bed if we’d liked – but we didn’t”).

Prohibition: MAY NOT, MUST NOT

One of the modal auxiliaries that expresses prohibition is MAY NOT.

However, its use is ambiguous as it may express two meaning that are only

differentiated by stress: He ‘may not go swimming with stress on MAY strongly

favors the possibility sense, whereas He may ‘not go swimming suggests the

permission sense, i.e. prohibition.

Interestingly MAY NOT and MUSTN’T, despite the diametrical opposition

of their positive meanings, are logical equivalents in negative sentences like: You may

not go swimming. You must not go swimming. These are both prohibitions, and the

only difference in their import is the more urgent and positive tone of later. The

reason for this curious equivalence is to be found in the inversion rule “change the

place of the negative and the term of the inversion system, and the meaning remains

the same”.

A glance at the semantic specifications of the sentence given above will show

that they fulfill the conditions of the rule, and are therefore cognitively synonymous.

The different categories of negation involved (“modal” in the case of MAY NOT,

“principal” in the case of MUST NOT) cancel out the contrast between MAY and

MUST.

There is and instance when only MAY NOT may be used to express

prohibition and this is the case of a prohibition that usually occurs in official context.

An example for this use could be found on the wall of public institutions, such as

Readers may not smoke in the library. But we could never find MUST NOT with

this use.

Speaking about prohibition, it would be interesting to go a bit further the strict

sense of the term and to say a few words about the negative forms of modals in

general. Each modal has two types of negative. One type of negative expresses the

absence of any necessity or duty to do something. The other type of negative

expresses what amounts to a prohibition; that is to say, a necessity not to do

something, or duty, obligation, or advisability not to do it.

Absence of necessity or duty is best expressed by either I (you, they, etc.) do

not have to, I need not or I do not need to; I have not to is correct but not common;

I have not go to is very common, but only in colloquial spoken English. All these

expressions are usually contracted in spoken English. These five negatives all apply to

each of the five affirmative expressions: I must (go); I have to (go); I have got to

(go); I should (go); I ought to (go). Prohibition negatives are formed simply by

placing NOT after MUST (to sow necessity not to do something) and after SHOULD

and OUGHT TO (to show duty, advisability not to do it).

The placing of not after the have or have to and have got to does nor form a

prohibition negative; it forms two of the five negatives expressing absence of

necessity or duty. As a result of this, the one expression MUST NOT becomes the

prohibition negative not only of MUST but also of HAVE TO and HAVE GOT TO:

I must go; I have to go; I have got to go but I must not go.

Obligation: MUST, HAVE TO, OUGHT TO, OUGHTN’T TO, MUSTN’T

The most common used modal that expresses obligation is MUST: I must go

now. (I am obliged to go now). MUST is used with reference to knowledge arrived at

through direct experience. In sentences with MUST, one can postulate a chain of

logical deductions. If we take into consideration John goes out and John must go out

we see that that the second sentence adds to the meaning of the first sentence the idea

of the existence of obligation. The presence of MUST in John must go out does not

only convey the obligation but shows us that there exists a state of affairs that causes

the obligation.

When MUST is used with the sense of obligation, we may speak of various

degree. Such a degree is the use of MUST to a little more than offer an invitation:

You must come again. In this sense it may refer to the future. A usual implication of

MUST in this sense is that the speaker is the person in authority; he is the one who

gives the orders. As a consequence of this, I must and we must convey the idea of

self-compulsion; the speaker exerts power over himself, perhaps through a sense of

duty or self-discipline. Used in questions and if clauses, MUST involves the hearer’s

authority instead of that of the speaker. A question such as: “must I do all the

shopping myself?” means: “Are these your orders?”

In this context, we may speak about a special sarcastic use of MUST with

you: Must you make that dreadful noise? (“For heaven’s sake stop it.”) If you

behave like a savage, at least make sure the neighbors aren’t watching.

HAVE TO also expresses obligation: You have to be back by ten o’clock.

(“You are obliged…”). The meaning of HAVE TO differs from the sense of MUST

in that authority of the speaker is not involved: HAVE TO conveys obligation

generally, without specifying who does the compelling.

Thus, in a military context, You must be back in camp… would be probably spoken

by an officer giving the order, while You have to be back in camp… could be spoken

by an ordinary soldier informing his comrades issued by someone else.

When MUST and HAVE TO are used with first person subject, the difference

between them is a difference between internal and external compulsion.

A sentence that expresses obligation by using HAVE TO such as: You have

to leave your car here. carries the supposition “… and I fully count on you doing so”.

In this respect, the meaning of HAVE TO differs form the auxiliary complex

OUGHT TO which is also used in a sense of obligation: You ought to leave your

car here does not imply You will leave your car here. This means that OUGHT TO

allows for the possibility that the constraining authority will be disobeyed. SOULD

may be used in all persons synonymously with OUGHT TO in this sense: You

should visit him again. Mary should get anew car. He should not speak so much.

SHOULD and OUGHT TO may express obligation both in the present and

the future: I really should stop smoking so much. I ought to have an operation at

once. I should go to see him again next week. You ought to be there at ten o’clock

tomorrow morning. Both OUGHTN’T and MUSTN’T may express obligation and

their sense is similar: You oughtn’t treat animals badly. You mustn’t treat animals

badly. Each of the present and future affirmative forms discussed so far has two part

affirmative forms. One past form shows that the obligation was in fact fulfilled, the

other past form shows that the obligation was not fulfilled. The first type of past of all

the present and future forms mentioned before: I must (go); I have to (go); I should

(go); I ought to (go) is the Past Tense of the verb HAVE TO. I (you, he etc.) had to

go. (i.e. There was an obligation for me to go – and I did in fact go.)

The second type of past of all four present and future forms is either

SHOULD or OUGHT TO followed by a Perfect Infinitive: I (you, he etc.)

should/ought to have gone. (i.e. There was an obligation for me to go – but I did not

go).