Future Tense of Modal Verbs

All normal verbs can be conjugated in the future tense.

e.g. I know, I will know. I do, I will do.

But I have noticed that we cannot conjugate the modal verb can in the future tense.

can, I will can?

Although we are able to conjugate the phrase be able (that has approximately the same meaning of can) to will be able, we cannot conjugate can. Is there a way to express can in the future tense without using the expression to be able?

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Additionally, need and dare are sometimes utilised as a modal verb.

I need not. Need I not? I dare say. Dare he do it?

Are we able to conjugate these verbs in the future tense as modal verbs?

If need were used as a ‘normal’ verb, an example of it in the future tense would be I will need to do it. Can we write that sentence by making need a modal verb?

Thank you.

Answer

In English, like in many other languages, we only have two tenses, a past tense and a present tense. Of course, we can still talk about the future. We use special present tense constructions to talk about the future. For example, we can us the present continuous:

• I am meeting my friends tomorrow.

We can use the present simple:

• The train leaves at 5pm.

We can use the "going to" future:

• I am going to punch him in a minute.

Or we can use modal verbs like can, will, may or might:

• I can/will/may/might leave tomorrow.

We can aslo use past tenses to talk about the future too:

• If you came tomorrow, we could go to the circus.

So even though we have no future tense we can still talk about future time.

The Original Poster's observation is correct, however, we cannot say will can or will must or must can and so forth. The reason is that we can only ever use one modal verb in a verb phrase. (Where modal verb means a central modal verb that can be used in the positive and negative and so forth, not marginal modals like need, dare or ought).