Modal Certainty, Probability, and Obligation: Understanding Modal Verbs

Modal certainty: will, must, be bound to

Assumption or prediction: will

Logical necessity: must

Probability or ‘reasonable inference’: should, ought

Extrinsic possibility: may, might, could

Summary of extrinsic modal

He will be there by now. (assumption/prediction based on experience or common sense)

I shall probably be back before you (prediction)

He must be there by now. (logical necessity, deduction based on evidence)

He can’t be there yet. (logical necessity negated)

He’s bound to be there. (modal certainty + inevitability)

He has to be there by now. (logical necessity, objective)

He’s likely to be there by now. (probability)

He should be there by now. (reasonable inference based on deduction)

He could be there by now. (tentative possibility)

He might be there by now. (neutral possibility)

He may be there by now. (weak possibility)

He may be intelligent, but he’s a bit of a prat (concessive meaning of may)

Volition: willingness and intention will, shall, ’ll

willingness: paraphrased: be willing to

Intention: intend to

Inescapable obligation: must, have to, have got to/ gotta, shall

Negation of the modals must and may: (must) needn't, don't have to, mustn`t, (may)may not/can't (obligation and permission - intrinsic meanings)

(must) can't, needn't, doesn't have to, (may) can`t, may not (necessity and possibility extrinsic meanings)

Non-binding obligation: should, ought

Summary of intrinsic modals and modal meanings

Will you sign here? (willingness)

Shall we go to the theatre? (suggestion/consulting addressee)

I’ll let you know tomorrow (intention)

You must try harder (inescapable obligation, subjective)

You have to try harder (inescapable obligation, objective)

We must go; we’ve got to/ gotta go (inescapable obligation, self-imposed)

You needn’t go; you don’t have to go (absence of obligation)

All competitors shall wear a number (inescapable obligation, formal)

You should drive more carefully (medium obligation, not necessarily fulfilled)

You can do it (ability, possibility, or informal permission)

It can be cold in Edinburgh (existential)

You may go now (permission, formal)

You can go now (permission, informal)

I would help you if I could (hypothetical)