If + past perfect, then + past conditional - Why's this wrong?

Question

What would have [VERB]ed if this park had been [VERB]ed? [User StoneyB answered:]

The second is semantically unacceptable in the circumstances you describe. The past perfect in the conditional clause and the irrealis modal past in the consequence clause mark this as a question about the past, not the future: you are asking about the past consequences of a past demolition, which would only be acceptable if you were indulging in historical speculation.

Alas, I don't apprehend the answer above; please enlarge on the problems here? The apodosis here is 'would have [VERB]ed', which is the past conditional tense, and so which concerns the past, not the future coherently with the above?

Answer 1

I think the OP has a point, unless I'm mistaking his question (although I understand StoneyB's correct answer given the scenario in the first line of the cited question).

Scenario 1: A mugging victim is giving her report to the police.

The assailant approached me from a poorly lit area near the park benches. I did not see him until it was too late.

Scenario 2: An editorial in the newspaper a week later, about that mugging, and others.

We have been asking for improved lighting in the park for several years, yet City Council has done nothing whatsoever to make the park any safer. What would have happened last week if the area near the park benches had been well lit? We cannot say with any certainty, of course, but the victim might have seen the assailant sooner——and she might have been able to turn and flee.

In the question cited, about demolishing the park, the demolition was under consideration--a possible future event. The tenses asked about make sense only with a possible|hypothetical past event.

OP asks:

Are you saying that What would have [VERB]ed if this park had been [VERB]ed? question is right, if the demolition had been (Is this had been right?) been a possible PAST event, BUT is no longer considered? Also, is the construct wrong if the demolition is still being considered?

What would have happened last week if the area near the park benches had been well lit.

What might yet happen is of no consequence to the choice of tense there. Ongoing discussions about adding some lights to the park have no bearing whatsoever upon the events of last week. The relevant hypothetical situation is situated in the past.

What would have happened last week if the park had been well lit?

Answer 2

What would have [VERB1]ed if this park had been [VERB2]ed?

You can only use this if there was (in the past) a possibility VERB2 may have happened in the past.

Since it didn't, we'll never know for sure, so any use of sentences like these are going to be a form of speculation, and talking about the past, or history - so that's what StoneyB meant by "historical speculation."

The right way to say it, if you want to talk about what happens if something else will happen, is:

What will VERB1{present tense} if this park is VERB2ed?

You probably can use would here without too much confusion (not sure if it's ungrammatical, it may be) but will is bit more clear if you are talking about a possible future condition. The word if already establishes "is VERB2ed" as a conditional.

You'll never go wrong using if-then:

If this park is VERB2ed, then what will VERB1{present tense}?