The if-clause (= conditional clause) expresses the condition - the verb in the conditional clause reflects the speaker's point of view on whether the imagined situation is possible, likely or impossible.
Yes.
In the main clause, if it is the second or third conditional, you use the modal verb with future-in-the-past meaning
I understand what you mean when you say a 'future-in-the-past meaning' but I certainly wouldn't describe it like that. I think it's better to say that there's a
resultative meaning, in that the main clause results from the condition clause. Bear in mind that this resultative logic is not necessarily temporal—that is to say that the result clause doesn't have to follow
in time (though that's often the case) but just that it has to follow
logically. That's the case in our example—the word
must is used to make a logical conclusion that
follows from the truth condition expressed in the condition clause.
My problem with must here (and with the sentence in the OP) is that it isn't should, would, might, could. Does must take or represent the form and the future-in-the-past meaning as should, would, might, could do it in the conditional ii or conditional iii sentence - is that actually possible ? ( Phew - that was hard work!)
I understand the question. I hope I've answered it sufficiently in my point above.
That's correct: Yes, I consider the conditional ii and conditional iii sentences to always have the same structure and thence the same meaning (in regard to the tense of the verbs).
The same
basic structure, yes, but the same meaning, no. When we classify the conditionals into types, we're classifying their structure more than anything else. This is an area of confusion that comes up again and again for both teachers and students alike. My view on this as someone who's been teaching this stuff for decades is that higher-level learners like yourself ought to abandon the classification of types and focus instead on the meaning of the sentence in use, i.e., the particular logical connection between the condition and the result. The classical division of conditional sentences into types is really just a handy and simplistic way of organising a very difficult and complex area of English language teaching. It isn't used by linguists. Many teachers including myself are rather reluctant to use it at all. When I told you that I'd class your sentence as a third conditional, I was reluctant to do so, but I thought it would be useful to say that to you. (I'm still not sure if that was the right thing to say!)
Conditional ii:
If-clause: if + past simple , main clause: modal verb (should, would, might, could) + infinitive without to
Conditional iii:
If-clause: if + past perfect, main clause: modal verb (should, would, might, could) + have + -ed form
I organise it more generally, like this:
Type 2
Condition clause: if + past subjunctive
Result clause: modal
Type 3
Condition clause: if + past perfect
Result clause: modal perfect
Any modal verb can be used in the result clause (depending on the meaning, of course) though the typical modal is
would. Also understand that even the conjunction
if is not necessary to express conditionality and none of the nine classical modal verbs are necessary in the result clause, either. The structures I've listed above are merely general patterns, not rules of usage.
Every grammar tells you so.
No, that's incorrect. In fact, this is one area of English that's especially notable for the variety of ways that it's presented and taught. Also bear in mind what I said above: the idea of four types of conditional is merely a convenience for teachers to break down complexity into simpler parts. It's natural that different teachers will do this in different ways, to suit their particular aims.
Why do you repudiate that?
Look, I'm trying to teach you something. If you want me to desist, then fine.
