A student asked me this question today about a sentence like:
(1) If Canada's population is 40 million, the Canadian economy will have been more dynamic.
I was asked if it corresponded, in a future conditional sense, to the third conditional sentence (2) If Canada's population had been 40 million, the Canadian economy would have been more dynamic.
To me, sentence #1 sounds utterly ungrammatical, and my tentative theory is that the ungrammaticality is because of the stative/non-action verb in the if-clause. I can come up with unusual–but grammatical–sentences using Future Perfect in the main clause and a Simple Present action verb in the if-clause, such as If she agrees to marry me, we will have lived together for a year by next Christmas. But I have not been able to dream up a corresponding, grammatical example that uses a stative/non-action verb in the if-clause, nor can I think of a way to transpose the meaning of #2 (third conditional) to #1.
I need some help with this, and my search of umpteen grammar reference books, Google, and the ELU archives has not helped. Please enlighten me.
Best Answer
Past
Present
You could say is when the clause introduced by the if is not a condition but a consequence, as in:
You could also use is if you doubt a fact, e.g.