1) There are only twelve modal auxiliary verbs, but they are used with very
great frequency and in a wide range of meanings. They express concepts or
attitudes relating to recommendation, obligation, necessity, and
prohibition; permission and refusal; possibility, expectations, probability and
certainty; promise and intention, ability and willingness.
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2) There are four paired forms - can, could; may, might; shall, should; will,
would; and four single forms - must, ought, need, dare. There are no other
forms, and all modals are therefore, to varying degrees, 'defective' verbs.
The two verbs need and dare present special problems; dare can follow the
grammatical patterns of either modal auxiliaries or lexical, 'regular' verbs,
whole need contrasts grammatically with the regular verb to need.
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3) The grammatical (or'formal') contrast between modals and regular verbs is
perhaps best illustrated and summarized in sentences with question tags:
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| | He | | | can | not | | can | he? |
| | | | may | | | may | |
| | | | need | | | need | |
| | | | dare | | | dare | |
| | | | ought | | to go, | ought | |
| He | | doesn't | want | | to go, | does | he? |
| | | | like | | | | |
| | | | need | | | | |
| | | | dare | | | | |
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The principal distinctive formal feature of modal verbs are, explicitly;
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a) negatibe sentences are formed by adding not after the modal verb;
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b) interrogatibe sentences are formed by inverting the subject and the
modal verb;
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c) there is no -s ending in the third person singular in the present tense,
as there is with regular verbs (he wants, likes, etc,);
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d) the modal verbs are followed by the infinitive of a verb without to
(except in the case of ought).
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4) All these features contribute to the distinction between the two
grammatical patterns of dare, and betoween the modal verb need and the
regular verb to need:
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| | Regular | | | Modal | | |
| He | dares | to go. | - | | |
| | needs | | | | |
| He doesn't | dare | to go. | He | dare | not go. |
| | need | | | need | |
| Does he | dare | to go? | Dare | he go? | |
| | need | | Need | | |
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Note that the modal verb need, and dare in its modal pattern, are used only
in negative and interrogative sentences.
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5) The modal verbs (including dare and need as modals) have no infinitive
form, and no participle forms. Hence the need on occasion for a number of
more or less synonymous expression having a fuller range of forms - be
able to, or have to, for example. It would not be possible to use can or must in
the following;
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I'd like to be able to speak English fluently. (infinitive)
No one has been able to solve the problem. (present perfect)
I'm having to read this very carefully. (present progressive)
You will have to pay extra for a single rooom. (infinitive without 'to')
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6) The modal verbs are also limited in their range of time reference. When
used with the 'present' infinitive of the main verb., they generally have a
present or future time reference:
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| | | can or could | |
| | may or might | |
| | will or would | |
| He | shall or should | help you (e.g.) immediately, later. |
| | must | |
| | ought to | |
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The use of the alternatives could, might, would, should, wuggests a more
tentative attitude on the part of the speaker. In requests, it represents what
is commonly called the 'polite' form;
Would you do me a favour?'
Could you pass the sugar, please?'
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7) This particular use of could, might, would, should, is consistent with their
appearance in eigher of two forms of conditional sentences (though there
may, of course, be slight differences in meaning between the two versions);
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| | | could | | | |
| | might | | tell | |
| I think he | would | help you if you | told | him a problem |
| | should | | | |
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8) It is misleading to regard could as the equivalent in past time of can, might as
the equivalent of may, etc. Of the four past tense forms (could, might, would,
should), only the first three are used to refer to past time when followed by a
present infinitive, and then only within a restricted range of meaningns;
He could speak several languages by the time he was ten.
He was very independent, and would never ask for help.
Try as he might, he couldn't get the car to start.
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The use of the four past tense forms is, however, automatic in the sequence
of tenses in reported speech:
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| | | can or could | | | could | |
| | may or might | | | might | |
| He | will or would | tell me. = | I said he | would | tell me. |
| | shall or should | | | should | |
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The four single forms must, ought to, dare, need, may be left unchanged in
reported speech:
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| | | mustn't | | | mustn't | |
| | oughtn't | | | oughtn't | |
| He | daren't | tell me. = | I said he | daren't | tell me. |
| | needn't | | | needn't | |
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9) We cannot, of course, use must, needn't or ought to with a present infinitive
to refer to a time earlier than the time of speaking. It is impossible to say:
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| | | must | |
| I | needn't | do it yesterday. |
| | oughtn't | |
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However, in the reported speech examples given above, there verbs do not
refer to a time earlier than the time of speaking. In the statement 'You
mustn't tell anyone.' the obligation (not to tell anyone) exists from the time
when it is expressed, i.e. from now onwards. Similarly, in the report I said
he mustn't tell anyone, the obligation (not to tell anyone) existed from the
time when it was expressed, i.e. from then on, and not at some time earlier.
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10) At this point, it is important to recognize a distinction between two uses of
modal verbs, as illustrated in tables 1 and 2 below. In table 1, the modal verbs
are all used to asset various degrees of likelihood regarding the truth
of the statement (It's certain, probable, possible, etc., that this is true),
whereas in table 2, the modal verbs are used to refer to ablility, duty,
willingness, permission, etc., in relation to the subject:
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| | | | | must | | logical conclusion |
| | | | can't/couldn't | | logical conclusion |
| | | | will/would | | belief |
| | 1 | He | may/might | be there already. | possiblity |
| | | | could | | possiblity |
| | | | should/ought to | | probability |
| | | | | | |
| | | | must/mustn't | | absence of obligation. |
| | | | needn't | | recommendation |
| | | | should/ought to | | promise |
| | 2 | He | shall | go immediately. | willingness |
| | | | will | | permission |
| | | | may | | ability or permission |
| | | | can | | |
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11) We can extend the range of time reference of the modal verbs as used in
table 1 and refer to past time by using the 'perfect' infinitive of the main
verb, as in table 1a:
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| | | | must | |
| | | can't/couldn't | |
| | | will/would | |
| 1a | He | may/might | have been there yesterday. |
| | | could | |
| | | should/ought to | |
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the use of the perfect infinitive in such cases generally refers to 'real' past:
it does not usually affect the truth of the statement, and in only a limited
number of contexts can it indicate 'unreal' past (i.e. contrary to past fact).
Note also that it is possible to use the present tenses can, will, may, with the
perfect infinitive, to refer to past time.
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If we wish to refer to real past time with the modal verbs as used in table2,
We either use the past tense of the modal verbs, if appropriate ( and if
available), or we use a synonymous verb phrase (had to, didn't need to, was
able to, was permitted to, etc.). If the modal verbs as used in table 2 are
followed by a perfect infinitive, they always indicate 'unreal' past:
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| | | needn't | |
| | should/ought to | |
| He | would | have gone yesterday. |
| | might | |
| | could | |
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Some of the complex problems of usage and meaning are discussed and
practised in the notes and exersised that follow. The modal verbs in their
various meanings are assingned to use 1 or use 2 as illustrated above.
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