On the page The Verb Structure Circle, I discussed the four basic building blocks of the English verb: the simple forms 1 (so-called ‘simple present’) and 2 (so-called ‘simple past’) and the aspects continuous and perfect.
What this basic approach to English verb structures does not cover is modality. What is modality? If you have read the page mentioned above, you will remember that one of the main semantic features of the two ‘simple’ forms is factuality. We express things we believe to be true facts using the two simple forms.
What if we are uncertain of the reality, truthfulness, certainty or factuality of what we want to express? To take an example: We are not sure, for instance, where we want to go in a strange city (and we forgot our navigation system) and we are looking for the restaurant a friend recommended, so we say something like: It could be that one at the corner, or it might be the other one opposite, or maybe we are in the wrong street … in the latter case we are not using a modal to modify the lack of concrete knowledge (or factuality) of the location we are looking for, but the word ‘maybe’, thus expressing our uncertainty lexically. In the other cases, however, we are using ‘could’ (be) and ‘might’ (be) – two modal auxiliaries. Notice that in the sentences including a modal the verb – in this case ‘be’ – stays in infinitive form, whereas in the sentence without modal auxiliary the verb (‘be’ in main verb function) changes its form according to ‘person’ (in this case ‘we’ are).
Another example: Let’s say we are not sure what we would like to do today so we start considering different options. We could (notice the modal here) say something like:
We could go to the zoo or we could stay at home, or we could do nothing….
The suggestive nature of my proposition is expressed by the modal auxiliary could.
Or let’s say I have a problem and need some advice; somebody could say to me something along the lines of:
You could do X; or
I believe you should do Y; or
You might consider doing Z.
If you look at the structure of the verb phrase, in each case you have a modal auxiliary and the basic form/infinitive of the main verb. If we substitute ‘do X, Y, Z’ we could say something like:
You could give him a phone call
You should send her an email
You might think about talking to her
In each of the cases, time is not an issue, as the main focus is on giving advice or making a suggestion or, as in the following example, promising to do something.
Will and ‘ll
Will and it’s contracted form ‘ll also belong to the group of modals.
Let’s look at the example:
I‘ll give him a ring later.
Though the promised activity is in the future, we would not – linguistically – speak of a future tense here (will-future, as you find it in many course books). It lies in the nature of promises, suggestions, predictions and advice etc. that the activities, if fulfilled, lie some time in the future from now. Note: If I leave out ‘later’ in the example above and say ‘I’ll give him a ring’, it is implied by the form that I intend to do it right away; in fact, I am offering to do something right away by using ‘ll. (In most cases, native speakers would use the contracted form and not ‘will’ when offering to do something at the moment of speaking.)
The number of modal auxiliaries in English is restricted to eight or nine – depending on if you include ought to (more about ‘ought to’ in a moment).
We also have want to, need to, have to and used to – commonly referred to as semi-modals. They do not modify the aspect of factuality, but express different kinds of attitudes like desire, need or obligation, and – in the case of used to – past habits:
I want to see (the film)…. It is my wish or desire…
She needs to go (to the dentist tomorrow). The speaker or ‘she’ believes in the necessity of a certain activity, in this case ‘going to the dentist’.
He has to leave (tomorrow). ‘Has to’ expresses obligation: some force, inner or external, is behind the activity, there is no choice, something ‘has to’ be done.
I used to go running regularly. (I don’t any more.)
All semi-modals, with the exception of ‘used to’ have second forms (‘past tense’ forms): wanted to, needed to, had to. Modal auxiliaries are not inflected.
Ought to is somehow in between the two groups: it shares the meaning of the modal auxiliary should, but structurally resembles the other three as it also goes with ‘to’ – it differs from the latter three in that it has no second form; in this respect it is the same as the eight modal auxiliaries. (I personally have not integrated ‘ought to’ into my active vocabulary, and always considered it more British; to me it means exactly the same as ‘should’)
Concerning word order, the modal auxiliaries behave like the other auxiliaries DO, BE, HAVE and are very regular. If we want to form a question, we swap the auxiliary with the subject; if we want to negate, we add not or n’t to the modal just as we would to the respective forms of DO, BE and HAVE (DO I will treat in a separate post):
It will rain ….. Will it rain…?
We shouldn’t go …. Should we go ….?
They might not come … (Questions with ‘might’ are rather rare, and I have never heard or read mightn’t)
DO and HAVE are different from the modals in that they have a second form and a third person singular -s (like ‘want to’, ‘need to’, and ‘have to’); BE – as in many languages – is different from the others in that it changes more often according to person.
Some might ask if ‘could’ is the second form of ‘can’, or ‘would’ the second form of ‘will’. In some cases, the answer is ‘yes’; it depends on the meaning of ‘can/could’ and ‘will/would’ respectively.
So far, I have only covered the forms:
We should leave soon.
We could go to the cinema.
She might come tomorrow.
You can/may go now.
I would like to go now.
I will go now.
Strictly speaking, you could say they all refer to some future activity, but the aspect of time is not at the core of their meanings.
However, we can also use modality with past time reference if we need or want to.
Let’s say e.g. I told someone to go to the dentist yesterday, but she didn’t and now she has a bad tooth ache. I gave her the advice to go, and now I want to rub her nose in it that she didn’t follow my advice:
You should have gone to the dentist (as I told you).
The form of a modal construction with past time reference is always the same: modal auxiliary + have + (past) participle.
They could have gone (earlier) – but they didn’t
We might have helped (if they had asked us) – but we didn’t
In the negative form, ‘not’ (n’t) is added to the modal:
They should not have gone – but they did
or with ‘could’:
You couldn’t have helped – even if you had wanted to, their was nothing you could have done.
He might not have done it – had the circumstances that led to him doing whatever he did been different.
I hope I could offer some clarity, and demonstrate the regularity of the respective forms. It is intended to be a descriptive summary of modal and semi-modal auxiliaries. It is not meant for learning. For that you need exposure to the language and listen to (or read) as much as you can. The more you encounter the language in question, the more you will (intuitively) grasp its meaning and use.