Modal Verbs

Definition

Modal verbs are a group of auxiliary (helping) verbs that add interpersonal meanings to clauses such as necessity, possibility, permission, uncertainty, ability, or obligation. They form part of the bigger system of modality (which you can read more about on Englicious). Interpersonal meanings are the ways we inject stance, opinion, or subjectivity into clauses: we’re not just saying something is factually true, but that it could be, might be, or must be true.

The English modal verbs are:

* shall is the missing modal verb but is almost never used in modern North American English

In the table above, it is tempting to read the right column as the past tense of the modals. While this is historically true, we technically say that modals have no tense, which is discussed below.

Modals have a wide range of meanings in different contexts, but you can see their effect on a clause in these examples:

Students eat in the cafeteria. (no modal: it’s a fact)

Students will eat in the cafeteria. (will = future)

Students can eat in the cafeteria. (can = if they want)

Students cannot eat in the cafeteria. (cannot = not allowed)

Students should eat in the cafeteria. (should = supposed to)

Students could eat in the cafeteria. (could = perhaps)

Students must eat in the cafeteria. (must = obligation)

Discovery

There are no modal verbs in the first sentence. Why not?

Form

Modals are a group of auxiliary (helping) verbs that are special in a number of ways:

• they don’t inflect*, that is we don’t add -s to the third person or change the verb in different tenses (*he cans play the clarinet)
• they are followed by a bare infinitive verb: that’s the base form of the verb (can eat, must go, should follow, etc.)
• they only need not to form the negative (I cannot, not *I don’t can)
• they can invert to form questions without using do/does/did (Could you pass the salt? Where will you go this summer?).
• they can form short answers without a main verb (Yes, we can! No, you won’t!) and tag questions (can we? should I? won’t you?).

* There’s a bit of debate about modal verbs and tense. Historically, modals formed the pairs you can see in the table at the top of this page: the verbs on the left were historically present simple tense (can, will, may, must, shall), and those on the right were past simple tense (could, would, might, should). But in modern English, this distinction is mostly lost, so we usually teach learners that modal verbs can’t change tense to avoid mistakes. The one pair where you sometimes see a clear present/past meaning is can/could, which is discussed below. For example, I could swim well when I was a child, but I can’t now.

Functions

There are four broad functions of modal verbs. Unfortunately, most modals are used for more than one purpose, so they appear under multiple functions (e.g. I can swim [ability] / Can I play outside? [permission]). There are also shades of meaning within each function. We will look at them briefly here and then look at more specific ways to practice analyzing and using modal verbs. Most ESL/EFL textbooks have very detailed discussions of the meanings of modal verbs, if you’d like to read more.

Ability

can … could

Both can and could express ability. Could sounds a bit less confident.

You can see the effects of climate change everywhere.

Could you play that note a bit quieter?

In some – but not all! – situations, could expresses ability in the past.

In the 17th century, people couldn’t travel easily from city to city.

I could touch my toes when I was younger.

However, something strange happens if you try to talk about a specific event, rather than a general ability, in the past. In this situation, only negative uses of couldn’t are possible:

OK: I couldn’t do my homework yesterday because the wifi wasn’t working.

UNCLEAR: *I could do my homework this morning when the wifi was fixed. (BETTER: I was able to do my homework this morning.)

 

Certainty

must … will .. should … can … could … may … might

The modals of certainty are organized roughly in order of strength (from the strongest, must, to the weakest, might), but the difference between some of the modals is minimal (e.g. it may rain tonight / it might rain tonight). Will indicates so much certainty that it actually expresses the future. That’s why we sometimes refer to will as the future simple tense. The modals of certainty are very frequently used in academic writing to hedge ideas: that is, to show that something might be true, but we can’t prove it.

This research shows that handwritten notes can lead to more learning than typed notes.

Corrective feedback should improve language development.

Studying abroad might make students more open to new cultures.

However, note that the negatives of these verbs line up in a different order:

cannot … must not … will not … could not … should not …may not … might not

Cannot means something is impossible, so it’s the strongest way to express negative certainty!

You can’t be serious!

It might not rain tomorrow.

Necessity/Advisability

must …. had better … should … ought to

Modals of necessity are also listed in order of strength from must (absolutely necessary) to ought to (desirable but not necessary). In speech, ought to sounds like “outta” and is often misspelled as a single word.

Grades must be submitted by 5pm today.

We ought to reduce the amount of meat we eat.

Note: Had better and ought to aren’t technically “pure” modal verbs because they have two words, but they behave almost exactly like other modals, so they are included here (i.e., we say you had better go and not *you had better to go;  we can’t inflect ought to and make it refer to the past; see semi-modals).

Permission

can … could … may …. might

These modals aren’t presented strictly in order of strength, although the modals on the right sound more tentative (can you help? vs. might you help?). Contrary to some opinions, can and may both ask for permission: only pedants respond to the question Can I take off my coat? with yes you can, but no you may not.

You can go outside after you’ve finished your math.

May I see the menu?

Would

The modal verb would deserves its own section because it has a number of functions that are unique among modal verbs:

Conditional and unreal clauses: If it were sunny today, I would cut the grass; if it had been sunny yesterday, I would have cut the grass. The room would be more welcoming without fluorescent lights.

Politeness: Would you like to eat indoors or outdoors? (compare to the more direct and less polite: Do you want to eat indoors or outdoors?)

Preferences, including ordering food: I’d (I would) like the salad. She would prefer to sit at the front of the classroom.

Habitual past: When I was a child, I would visit my grandparents every Saturday.

Future-in-the-past: From that moment, I knew I would always love the mountains.

There are more detailed and complex explanations of modal verbs in many grammar books and websites. For our purposes, it’s most important to recognize them and align them with the WIDA KLUs. We would expect to find modal verbs especially in texts that:

Narrate – to speculate, tell the future, and describe characters’ abilities

Inform or Explain – to show certainty or the lack of it; or to show sequences (after one thing happens, another will).

Argue – to express opinions, recommendations and calls to action, or to hedge or boost the strength of claims and evidence

What next?

Semi-modal verbs

Perfect modal verbs

Other ways to express modality

Interpersonal meaning