Given the following sentences that use will in the if clause (which is seldom with if-clauses and therefore, I'm not sure they all are even grammatical or not).

  • If you will/would kindly lend me your book, I will be thankful to you.
  • If you will not/would not mind lending me your book, I will be thankful to you.
  • If you will/would wait for a while, I will check it for you.

  • If you will use it, you can have it
  • If you will not arrive before six o'clock, I cannot meet you.

What if the last sentence is modified as follows?

If you will not be arriving before six o'clock, I cannot meet you.

Once upon a time, it was found in a grammar book.

If the play will not be finished until ten o'clock, I will have to spend the night at your place.

Can the following version of this sentence have a different meaning (or no meaning at all — a wrong sense)?

If the play is not going to be finished until ten o'clock, I will have to spend the night at your place.

After all, the question is when is will used in if-clauses as the title implies?

Moreover, both the following sentences appear to indicate a probable condition.

  • If he came, I should help him.
  • If he came, I would help him.

Using should and would interchangeably in such contexts implies a significant difference in meaning?


3 Answers 3


There seem to be several questions here. I’ll answer the one in the title.

I believe foreign learners are taught, at least at the lower levels, that an if clause cannot contain the modal verb will . This is good advice as far as it goes. We have to say If you run, you will catch the train and not If you will run, you will catch the train. However . . .

Will (’ll) and won’t may be used in the if clause to express the possibility of willingness (or its absence) on the part the person addressed. It can be used as a form of politeness, as in If you ’ll come this way, I’ll show you a few samples. In its negative form it can be a threat, as in If you won’t try harder, I’m not going to help you.


As I often say, this topic seems to come up with some frequency here.

The answer lies in the different Deontic 'be willing to (do)' and Epistemic 'be expected to (occur)' senses that will has; only the Deontic sense is allowed in If-clauses.

Every modal auxiliary verb has at least one Epistemic and one Deontic sense, and they often have very different grammar and meaning, especially in hypothetical situations.


To foreign learners, it is important that rules should not be broken, and they are not, even in the case of "If you will come this way, I will show you a few samples."

The rule which says that 'if' is never followed by future tenses holds!

The verb form 'you will come' is not one thing – the Future Simple of 'to come' – but two: the Present Simple of the modal auxiliary 'will', meaning 'be willing to' + the Bare Infinitive of the verb 'to come'.

Et voilà, le tour est joué…

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