5. May and Can for Possibility

A. Form

may/might for present and future.

might in the conditional and after verbs in the past tense.

Infinitive: to be + likely

B. May and might are often used to talk about one kind of possibility: the possibility (‘chance’) that something will happen, or is happening. Might is not the past of may; it suggests a smaller (present or future) probability than may.

I wonder where Emma is. She may be with Nelly, I suppose.

Peter might phone. If he does, could you ask him to ring later?

C. May with different types of infinitive.

1. May in combination with the simple infinitive usually refers the action to the future.

He may/might come soon.

The action may also refer to the present but only with stative verbs.

He may/might be ill.

He may/might not know about it.

2. May in combination with the continuous infinitive of dynamic verbs refers the action to the present or future.

It’s too late to phone him now. He may/might be sleeping.

He may/might be waiting at the station.

(Perhaps he is waiting at the station.)

He may/might be waiting at the station when we arrive.

(Perhaps he will be waiting...)

3. Both may and might can be used with the perfect infinitive to talk about the possibility that the past events happened.

Polly’s very late. - She may have missed the train.

What do you think that noise was? - It might have been a cat.

Might, not may, must be used when the uncertainty no longer exists, i.e. to say that a past event was possible, but didn’t happen. So in the sentence: You shouldn’t have drunk the wine: it may/might have been drugged the words it may have been drugged would indicate that we are still uncertain whether it was drugged or not. ...it might have been drugged could have the same meaning but could also mean that we know it wasn’t drugged.

4. The combination of may with the perfect infinitive may also indicate an action begun in the past and continued into the moment of speaking. If may is followed by a stative verb the simple infinitive is used. However, if may is followed by a dynamic verb, the continuous infinitive is used.

He may have been at home for about two hours.

He may have been waiting for us for an hour.

5. May is not used interrogatively in questions about possibility. Instead, we express the idea by do you think? or a construction with be + likely:

Do you think he is alone? (Not: May he be...?)

Is it likely that the plane will be late? (Not: May the plane be late?)

Is it likely to rain, do you think?

6. Might must be used in conditional and when the expression is introduced by a verb in the past tense:

If you invited him he might come.

He said he might hire a car. (indirect speech)