First Conditional

Yale Wale posted:

I'd like to know if these examples are wrong: 

1. If comedian AY will perform at the show, I will definitely attend.
2. If you won't tell Dad about it, I'll show you the tattoo on my butt.
3. If Ronaldo will play in tomorrow's match against Liverpool, I will buy a ticket to watch the game.

Hi, Yale Wale,

Sorry for the delay. All three of those sentences are correct.

Yale Wale posted:

If they are correct, what is the difference between them and the last example I quoted from CGE?

Here is the last example you quoted from CGE:

Yale Wale posted:

✪ 'Will' and 'shall'  are used in the main clause, not the if-clause:

If he moves to Manchester, he will have to sell his house in Bristol.

(If he will move to Manchester, he will have to sell his house in Bristol.)

The important grammatical difference between your examples (1), (2), and (3), on the one hand, and that example from CGE, on the other, is that the "if"-clauses in the first three examples concern a person's willingness to do something, whereas the "if"-clause of the CGE example is purely factual.

That said, it is only by considering the CGE example as a whole that we can determine that the "if"-clause is purely factual and does not concern his willingness. If the main clause were suitably revised, "will" would work. Consider the following variation:

(X) If he will move to Manchester, we shall all be very grateful.

In (X), the "if"-clause is clearly about his willingness to move to Manchester. It is his willingness to move there that is in question, not merely the possible future circumstance of his doing so. For that meaning, the normal Type 1 conditional would be used: "If he moves to Manchester, we shall all be very grateful."

How do we know that the "if"-clause does not concern his willingness to move to Manchester in "If he {moves / *will move} to Manchester, he will have to sell his house in Bristol"? We know it because of the inference that follows, which is purely matter-of-fact. The one circumstance logically requires the second.

Yale Wale posted:

How do I know when not to use 'will' in a conditional clause.

When in doubt, don't do it. The use of "will" in an "if"-clause is not exactly a "First Conditional." I don't recommend teaching your students the use of "will" in "if"-clauses as part of a lesson on the First Conditional. If you teach it at all, teach it as separate from the three canonical types. There are many more types than three!

Apart from the use of "will" in an "if"-clause to refer to willingness, "will" is also sometimes used in "if"-clauses to refer to the inherent capacity of something. Below are a couple of examples with this other usage. Again, I do not recommend including these in a lesson on Type 1 conditionals.

(Y) If the car will seat six people, we needn't take separate cars.
(Z) If the box will hold all ten books, we won't need to give any of them away.

Wonderful! I am so grateful to you, Mr David. Your responses are always excellent.