Appendix:English modal verbs

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Modal verb

Introduction

This is a brief overview of modal auxiliary verbs in common usage in English.

It is intended to be orientative, showing how English modal verbs can vary in their modal functions. It is not intended to be an in-depth complete grammar on the subject. The examples are here to give a grammatical glimpse at the uses. However, it must be borne in mind that without context, the examples will be one-dimensional. The choice of modal verb at any time depends overwhelmingly on the nuances needed in any conversational exchange, or written piece.

Examples of English modal verbs:
can, could, will, would, shall, should, may, might, must, ought, need and dare

Examples of English modal verbs – negative contractions:
can’t, couldn’t, won’t, wouldn’t, shan’t, shouldn’t, mayn’t, mightn’t, mustn’t, oughtn’t, needn’t and daren’t

Some other constructions with modal functionality:
be able to, have to, would rather, would like to, had better, bound to

Typical moods described:
While, in linguistics, English modal verbs are said to have only three basic modalities (epistemic, deontic, dynamic), in common usage it is more practical to sub-divide these into some clearly recognisable modal functions.

ability, obligation, permission, requests, suggestions, promises, probability, possibility, necessity, advice, criticism, courage, preference
– and some of their opposites –
inability, prohibition, freedom from obligation, lack of permission, improbability, impossibility, avoidability, lack of courage

Ability

Present

can:
I can play the piano.
– I have the ability to play the piano.

can’t:
I can’t play the violin.
– I do not have the ability to play the violin.

be able to:
I am able to play the piano.
– I have the ability to play the piano.

be able to:
I am not able to play the violin.
– I do not have the ability to play the violin.

Usage Note: Stative verbs, (verbs which do not normally use a continuous inflection - See Category:English stative verbs), especially verbs of perception such as "see", "hear", "feel", etc. commonly use "can" to indicate the continuous sense. E.g. "I can see my house from here." Not ~~"I am seeing my house from here".~~ ---- "I can feel a lump on my hip." Not ~~"I am feeling a lump on my hip"~~ ---- "I can understand some of what she is saying." Not ~~"I am understanding some of what she is saying."~~

Future

Note: Can does not have a future inflexion, and will can is not grammatically possible.

will be able to:
I will be able to play the piano.
– I will have the ability to play the piano.

will not be able to:
I will not be able to play the violin.
– I will not have the ability to play the violin.

Past

could:
I could play the piano.
– I had (used to have) the ability to play the piano.

couldn’t:
I couldn’t play the violin.
– I did not have the ability to play the violin.

be able to:
I was able to play the piano.
– I had the ability to play the piano.

be able to:
I was not able to play the violin.
– I did not have the ability to play the violin.

Note: The choice between could and be able to is often, but not always, based on using could for a general modality, and be able to for a particular occasion. E.g. – I couldn’t play the piano, but I was able to play Chopsticks if and when required.

Modals

Note: Can any other modal verb is not grammatically possible. So “be able to” is employed instead.

Examples: I should be able to play the piano. – I might not be able to play the piano. – and so on.

Interrogative

can:
Can you play the piano?
– Do you have the ability to play the piano?

be able to:
Are you able to play the piano?
– Do you have the ability to play the piano?

could:
Could you play the piano?
– Did you have the ability to play the piano? – However – this use of “could” is ambiguous, and would usually be reserved for a simple polite request to play the piano.

be able to:
Were you able to play the piano?
– Did you have the ability to play the piano?

Obligation

Present and Future

In present and future, there are degrees of obligation (a), Or prohibition (b):
1. The speaker believes that there is an obligation / prohibition. The speaker has authority to impose, or believes that the authority is correct.

(a) must:
You must wear a seat belt.

I must do my homework.

(b) mustn’t:
You mustn’t drink and drive.

I mustn’t be late for work.

2. The speaker believes that there is an obligation / prohibition. The speaker does NOT have authority to impose, or believes that the authority is overly strict.

(a) have to:
You have to stick to the speed limit.

(b) can’t:
I can’t be late for work.
– (Note that “don’t have to” does NOT mean prohibition.)

3. The speaker believes that there is probably an obligation / prohibition. The speaker is advising of the existence of this.

should:
You should slow down in fog.
ought:
You ought to slow down in fog.

shouldn’t:
You shouldn’t answer your mobile phone when driving.
oughtn’t:
You oughtn’t to answer your mobile phone when driving.

Past

Note: “Must” has no past inflexion. The past inflexions of “have to” are used for obligation, and “couldn’t” is used for prohibition.
have to:
Last Sunday I had to go to work.

couldn’t:
I couldn’t go into a pub until I was 18.

Modals

Note: Modal verbs cannot be used together in most dialects of English. Thus, in standard English, “have to” may be used for obligation:
Example: might have to:
I might have to work on Sunday.
– It is possible that I will be obliged to work on Sunday.

Interrogative

Note: “Must” or “have to” depending on the type of obligation perceived.
must:
Must I get a license?
– Is there an obligation, imposed by authority, to get a license?
have to:
Do I have to go to the meeting?
– Am I obliged to go? – (I don’t really want to go, perhaps it is optional.).

Necessity

We have seen that must indicates absolute necessity to do. (Obligation). And mustn’t indicates absolute necessity NOT to do. (Prohibition).

While need is not a modal verb, however, needn’t is used modally to indicate absence of obligation, it is not necessary. Similarly, not have to also indicates absence of obligation.

Present

needn’t:
You needn’t get a visa to go to France.
not have to:
You don’t have to get a visa to go to France.

Past

Note: compare normal verb need in past didn’t need to with modal verb needn’t have.

needn’t have:
You needn’t have got a visa.
– You got one, but it wasn’t necessary.
didn’t need to:
We went to France and we didn’t need to get one.
– We didn’t get one, because it was not necessary.
didn’t have to:
We went to France and we didn’t have to get one.
– Again, we didn’t get one, because it was not necessary.

Permission

There are many ways of asking for, and giving permission. The choice of modal verb often depends on contextual and subtextual influences such as degree of formality, etiquette, and expectations.

Requests for permission

Note: Permission requests are only made in first or third person. I, We, S/He, They.

Most formal to least formal:-

might:
Might I take tomorrow off?
– Formal, expecting a negative answer.
may:
May I take tomorrow off?
– Formal, expecting a positive answer.
could:
Could I take tomorrow off?
– Peer request, no expectations.
can:
Can I take tomorrow off?
– Informal, expecting a positive answer.

-

Also many variations of the form:
I was wondering if I might take tomorrow off?
,
Would it be possible for me to take tomorrow off?
, and so on.

Giving permission

Note: Granting permission is only made in second or third person. You, S/He, They.

Most formal to least formal:-

may:
Yes. You may take tomorrow off.
– Formal
may:
No. You may not take tomorrow off.
– Formal
can:
Yes. You can take tomorrow off.
– Informal
can’t:
No. You can’t take tomorrow off.
– Informal

Past

might:
Yesterday I said you might take the day off.
– Formal
could:
Yesterday I said you could take the day off.
– Informal

Requests

There are many ways to request someone to do something. The choice of modal verb often depends on contextual and subtextual influences such as degree of formality, etiquette, and expectations.
Note: Requests for someone to do something are normally in second person only: You.

Simple requests. Most formal to least formal:-

could:
Could you clean up, please?
– Formal request
would:
Would you clean up, please?
– Less formal request
can:
Can you clean up, please?
– Informal request
will:
Will you clean up, please?
– Very informal. More of an order than a request.
would you mind not:
Would you mind not smoking, please?
– Polite order to stop doing something.

Requests for help

Note: These help questions, when not posed directly with the verb, are often formed by “wh-” words shall in first person. Also common are can and could.
shall:
How shall I clean this stain?
What shall we do to fix this?
can:
How can I clean this stain?
What can we do to fix this?
could:
How could I clean this stain?
What could we do to fix this?

Suggestions

Are a type of request, using shall or may in the first person.

shall:

Shall I take your coat?

Shall we go now?

may:

May I take your coat?

May we go now?

Promises

Present and Future

Promises are normally indicated by will and won’t. "Shall" is sometimes used in formal contexts, such as business promises.
will:
We will be home before midnight.
won’t:
We won’t make too much noise.
shall:
We shall deliver the goods before the 30th
shall:
We shall not invoice until we have your signed receipt of goods.

It is worth noting the firm promise expressed by will continuous inflexion.

We will be flying at 30,000 feet, and we will be landing at 16.00 local time
– Typically, pilots use this format as it implies an absolutely firm promise.

Past

would:
We said we would be home before midnight.
– Reporting an earlier promise.
wouldn’t:
We said we wouldn’t make too much noise.
– Reporting an earlier promise.

Refusal

Refusal can be personal, or ergative.
won’t:
We won’t leave.
– Personal refusal to do something.
shan’t:
No, I shan’t.
– Personal refusal to do something. This form is not common, and is considered by some to be un-educated.
won’t:
The car won’t start.

The door won’t open.
– Ergative (“won’t” = “refuses to”), an object does not perform according to one’s wishes.

Probability and Improbability

Modal verbs are commonly used to express degrees of probability and possibility.

Future

Predictions, from certain to uncertain to certainly not.
will “be -ing”:
It will be raining tomorrow.
– I predict rain for tomorrow (I am certain. I have proof.).
will:
It will rain tomorrow.
– I predict rain for tomorrow (I could be wrong, but I think I am right.).
could:
It could rain tomorrow.
– I predict rain for tomorrow, possibly. (I think there is a good chance of rain.)
should:
It should rain tomorrow.
– Somebody said there would be rain, so perhaps there could be rain. (I don’t really know.).
might:
It might rain tomorrow.
– I predict there is about a 50% chance of rain.
mightn’t:
It might not rain tomorrow.
– I predict there is about a 50% chance of no rain.
shouldn’t:
It shouldn’t rain tomorrow.
– Somebody said there would not be rain, so perhaps it won’t rain. (I don’t really know.).
won’t:
It won’t rain tomorrow.
– I predict no rain for tomorrow (I could be wrong, but I think I am right.).
won’t “be -ing”:
It won’t be raining tomorrow.
– A dry day for tomorrow. (I am certain. I have proof.).

Conditional

In conditional expressions, modal verbs of probability and possibility are used in the result clause.
will:
If I go to Paris, I will visit the Louvre.
– Almost certain.
might:
If I go to Paris, I might visit the Louvre.
– A possibility.
won’t:
If I go to Paris, I won’t visit the Louvre.
– Almost certainly not.

Possibility and Impossibility

While probability and possibility are two distinct concepts, they are intimately connected when expressed by modal verbs. If anything is expressed as probable, then, by logical inference, it is also possible. So, any of the expressions of probability can be used as an expression of possibility.

However, there are some expressions where modal verbs are used simply to express possibility:

Future and Present

can:
Bee stings can hurt.
– Present possibility.
can:
It can rain a lot in Seattle.
– Present and future possibility.
could:
It could be true.
– This is a possibility.
may:
It may be true.
– This is a possibility.
might:
It might be true.
– This is a weak possibility.
must:
It must be true.
– This is a logical certainty.
can’t:
It can’t be true.
– This is an impossibility.
couldn’t:
It couldn’t be true.
– This is a less likely possibility. It is probable.
bound to:
It is bound to be true.
– This is a logical certainty.
would:
It would be true.
– This is a possibility.

Past

Note: modal have participle to indicate the past.
must have:
The Butler must have murdered the Countess.
– This is a logical certainty. I have circumstantial evidence.
could have:
He could have murdered the Countess.
– It is possible that he did this. He had the opportunity.
may have:
He may have murdered the Countess.
– It is possible that he did this.
might have:
He might have murdered the Countess.
– It is possible that he did this. He had the motive. But
He might not have murdered her.
couldn’t have:
He couldn’t have murdered the Countess.
– It is unlikely that he did this, but not impossible.
can’t have:
He can’t have murdered the Countess.
– This is certainly impossible. I have proof.

could have:
You’re very lucky. You could have been seriously hurt.
– It didn’t happen, but it was possible.

Conditional

In conditional expressions, modal verbs of probability and possibility are used in the result clause.
can:
If I go to Paris, I can visit the Louvre.
– It is a real possibility.
could:
If I go to Paris, I could visit the Louvre.
– It is a possibility.
could:
If I went to Paris, I could visit the Louvre.
– It is a hypothetical possibility.
could have:
If I had gone to Paris, I could have visited the Louvre.
– It is a hypothetical possibility, in the past, which never happened.

Advice and Criticism and Regrets

Note: should and ought are associated with these two modes. They are interchangeable, but some consider ought to be a bit stronger than should. Also must and have to – normally associated with obligation – can be used for strong advice
should:
You should take more exercise.
– Advice to do.
shouldn’t:
You shouldn’t eat so much.
– Advice to stop doing.
ought:
You ought to take more exercise.
– Advice to do.
oughtn’t:
You oughtn’t to eat so much.
– Advice to stop doing.
must:
You must take more exercise.
– Strong advice to do.
mustn’t:
You mustn’t eat so much.
– Strong advice to stop doing.
have to:
You have to take more exercise.
– Strong advice to do.
had better:
You had better get some more experience.
– Strong advice to do.

Some advice can be construed as criticism:

shouldn’t:
People shouldn’t drive so fast.
ought not:
My boss ought not to make me work late on Fridays.

Past

Note: should or ought have. This structure is almost always criticism of a past action.
should have:
You should have stopped at the lights.
shouldn’t have:
You shouldn’t have been driving so fast.
ought have:
You ought to have studied more.
ought not have:
You ought not to have gone to so many parties.

Note: In first person, this structure is often used to express regret
should have:
I should have studied more. (If only I had not gone to so many parties)

Preference

Note: would like to and would rather

Questions

would like to:
Would you like to see the countryside?
would rather:
Or would you rather go into town?

Statements

would like to:
I would like to rest this evening rather than see the sights.
would rather:
I would rather go into town tomorrow than today.

Courage

Note: dare is associated with courage. Dare is used both as a modal verb and as a normal verb. The modal form is most commonly found in negative and interrogative phrases in the present.
Normal verb:
I dare you to jump.
Normal verb:
Do you dare to jump?
Modal verb:
Dare you jump?
Normal verb:
I don’t dare to jump.
Modal verb:
I dare not jump.
Modal verb:
I daren’t jump.
Normal verb imperative order:
Don’t you dare climb that tree!

Tag Questions

Using modal verbs in tag questions is covered in Appendix:English tag questions.
Eg.
It will be difficult, won’t it?

Would – past habit

would is sometimes used to denote habitual repeated actions in the past. Similar to used to, but not used with stative verbs.
would:
We would go to the beach every Saturday.
– We used to go to the beach (as a repeated habitual action). It implies that we no longer do this.
used to:
We used to own a Model-T Ford.
– “Would” cannot be used in this stative case.