Understanding Modality and Modal Verbs in English
Understanding Modality and Modal Verbs
Modality is a semantic category of the verb expressing the speaker’s attitude towards a proposition. The primary grammatical markers for modality in English are the modal verbs. Two major kinds of modality are distinguished: Epistemic and Deontic.
Deontic (Intrinsic) Modality
Deontic modality concerns modes of permission, obligation, ability, and volition, involving some kind of intrinsic human control over events.
Obligation and Compulsion
The modal meaning of obligation and compulsion is expressed by the following modal verbs:
- Must: The most categorical, denoting the speaker’s authority. The listener is expected to obey. Example: You must do your work.
- Have to: Expresses general obligation. Example: You have to be more polite to your mom.
- Should / Ought to: Indicate advice or recommendation, ranking third in strength. Example: You should read this book.
- Need: Denotes the smallest degree of necessity, used mainly in negative sentences. Example: You needn’t bring a cake.
All the examples above refer to the present time.
Past Time Obligation
Past-time reference for obligation is expressed using the past forms of these modals, with one exception: must has no past form. Instead, had to is used, particularly in narratives. Example: I had to do my homework when my sister came.
In reported speech, either must or had to can be used if the speaker wants to add stress. Example: The teacher said that I must/had to do a test.
Should and ought to are generally preserved in reported speech. Example: She said that I should be more polite to her.
When should and ought to are used with a perfect infinitive (e.g., should have done), they express a past obligation that was not fulfilled and often indicate a strong degree of disapproval. Example: She was really sad last night. You should have been more polite to her. The negative forms (e.g., should not have done) indicate the opposite situation, also with disapproval. Example: You should not have invited her with us.
The past form of need, which is needed, is mostly used in narratives and in positive sentences in reported speech. Example: I thought I needed to drink so much last night. The construction needn’t have done expresses an action performed in the past that was not actually necessary. Example: She needn’t have worried about the exam. She did excellently in the end.
Permission
The modal verbs may and can express permission.
- May: Stronger, often involving the speaker’s authority. Example: Now, you may leave the room.
- Can: Indicates general permission. Example: Employees can smoke outside the building.
These modals can be used in all sentence types. Their past forms, might and could, are used in reported speech and narratives with past-time reference.
Ability
Ability is primarily expressed by can, denoting someone’s skill or capacity to do something. It is often interchangeable with the expressions be able to and manage to. Example: I can swim.
The past form could is used:
- In interrogative sentences: Example: Could you help me with this?
- In negative sentences indicating inability: Example: I couldn’t come yesterday.
- In positive sentences when referring to a general ability over a period of time in the past: Example: I could hear the rain pattering on the roof all night long. (For specific past achievements, was/were able to or managed to is often preferred).
Volition
Modal verbs will and shall express volition (willingness or insistence).
- Will: Can denote willingness. Example: Kate will help me – she is always willing to help. It can also denote the insistence of the subject. Example: He will marry that woman, whatever you say. (Stress indicates insistence).
- Shall: Can express insistence, often showing the speaker’s authority or determination. Example: He shall marry that woman, whatever you say.
Epistemic (Extrinsic) Modality
Epistemic modality involves the speaker making judgments or assessments about the likelihood (possibility, probability, certainty) of propositions or events.
Logical Necessity or Assumption
This is expressed by must, have to, should, and ought to.
- Must: Denotes a high degree of certainty (surely, undoubtedly). Example: She must be in the hospital. Now it’s her shift.
- Have to: Used less frequently for epistemic meaning, suggests ‘most likely the case’. Example: She has to be in the hospital. Now it’s her shift.
- Should / Ought to: Mean ‘it is very likely so’. Example: She should/ought to be in the hospital.
The interpretation (factuality vs. non-factuality) depends on the combination of time reference and verb aspect (form).
- Present Time + Progressive Aspect (duration, incompletion): She must be reading a book.
- Past Time + Perfect Aspect (finished action): She must have read the book.
- Past Time + Perfect Progressive Aspect (prior duration, incompletion): She must have been reading a book.
Possibility and Probability
This is morphologically expressed by the modals may, can, could, and might.
- May: Implies a possibility, sometimes with a slight degree of doubt.
- Can: Denotes theoretical possibility; often weaker than may in epistemic sense and common in questions or negative contexts regarding possibility.
- Could: Expresses possibility, often weaker or more tentative than can.
- Might: Expresses the slightest degree of possibility; often interchangeable with may but sometimes considered more tentative.
Predictability
Expressed by will and would, this type of modality is closely related to Logical Necessity.
- Will: Used to make predictions based on prior knowledge or characteristic behavior (parallels must). Example: That’ll be the postman. (Predicting based on usual time).
- Would: Shows a lesser degree of certainty in predictions (parallels should/ought to). Example: He would be about 60 now.
Predictability generally refers to the present or future.
Modals in Questions and Negation
It is important to note the behavior of modals in questions and negative sentences, especially in epistemic contexts:
- Questions: Only can and could typically occur in questions expressing doubt about an epistemic possibility. Example: Could she have finished the report by then?
- Negation: In negative constructions expressing epistemic modality, may, might, can, and could are common.
- May not / Might not: Express ‘internal negation’ – it is possible that something is not the case. Example: She may not have finished the report. (Meaning: It’s possible she hasn’t finished it).
- Cannot / Can’t / Couldn’t: Express ‘external negation’ – it is impossible that something is the case. Example: She cannot have finished the report. (Meaning: It’s impossible that she has finished it).