A prediction made in the past that affects something we will do in the future

Please ignore the factual accuracy of this sentence and focus on the tenses used.

If the Mayans were wrong to end the calendar on Dec. 20, 2012, we'll use your donation to fund 2013 programming.

I’d like to know:

1. if it is correct, and

2. what it would be called.

Solution 1:

It seems to me that FumbleFingers is right to say that this is a simple past conditional. I think the basic flaw in the original sentence is the use of the present infinitive in the conditional clause, which is awkward at best, and very likely a grammatical error. The sentence consists of a main independent clause: "We'll use your donation to fund 2013 programming" [MC], coupled with a subordinate dependent clause expressing condition, and that subordinate clause is really two subordinate clauses in disguise. If the sentence is reconstructed for purposes of evaluation, we could have alternatives like:

1. [MC], if [events show in the future] that the Myans were wrong [in the past] when they ended [in the past] the calendar on...
2. [MC], if the Mayans wrongly ended the calendar... [condition stated only in terms of past]
3. [MC], if the calendar doesn't end on ... [condition stated only in terms of future]

I think this shows that the original conditional subordinate clause tries to state two events with different temporal states: 1) If events show [in the future], and 2) that the Mayans wrongly ended the calendar [in the past]. The first is stated implicitly, as E. Ashworth pointed out, the second explicitly. Using the present infinitive makes a muddle of this by appearing to inject another temporal state. I conclude that in the original construction the past infinitive "to have ended" is gramatically required, but that the sentence would still be stylistically awkward even with that change made.

Oh, and I think the main verb were in the subordinate clause is properly in the subjunctive mood, expressing uncertainty. Indeed, part of the problem with the sentence is that one way to look at the way were is being used here is as a future subjunctive, elliptically expressed: "If the Mayans were shown to have been wrong...." This reading gives the sense of an uncertain state to be resolved in the future. The question of mood here is, IMHO, a red herring. The real issue is proper representation of the temporal states.

Solution 2:

This is an syntactically unexceptionable Conditional sentence of the type sometimes called the first conditional, which is used

to express a hypothetical condition that is potentially true, but not yet verified. The conditional clause is in the present or past tense and refers to a state or event in the past. The result can be in the past, present, or future. —Wikipedia

FumbleFingers' identification of a simple past in the conditional clause (protasis) is entirely correct. If the Mayans were ... cannot possibly be subjunctive, because the result clause (apodosis) is cast in the indicative. This is clearer if we substitute a third-person singular subject in the protasis:

✱If Tortugero Monument 6 were wrong, (then) we'll use &c is not English.

The meaning must be

If Tortugero Monument 6 was wrong, (then) we'll use &c 

As for recasting to end into the “past infinitive” construction, which Borstal urges and FumbleFingers appears tentatively ready to accept:

This construction might better be called the perfect infinitive, since it is the infinitive of a perfect construction. Its function is to define its “Event” time as prior to some other “Reference” time — which may or may not the same as “Speech” time.

In the case at hand, R-time is not S-time but the past time at which the Maya were wrong. Casting E-time —the time when the Maya made their prediction—into the perfect would imply that they did not become wrong until some time after the prediction. This is absurd: the wrongness inhered in the prediction itself, the Maya became wrong simultaneously with making the prediction and continued to be wrong as long as they maintained the prediction. E-time and R-time are identical, and it is proper to cast E-time into the “present infinitive”, which collocates E-time and R-time:

You were wrong to say X yesterday.
You are wrong to say X today.
You will still be wrong to say X tomorrow.

EDIT: (in addition to adding the important qualifier syntactically to my first sentence):
FumbleFingers points out that the straightforward syntax of this construction is in this instance profoundly confused by the semantic implications of the content, and I think he is right. The discourse itself is about time—more, it is about a discourse about time. And verifying the hypothetical would in effect render meaningless not only the hypothetical itself but also very system of tensual (is that a word?) reference in which it is expressed. Dealing with those semantics blurs any sense of stability in the syntax.

Solution 3:

Superficially it looks like past subjunctive (usually used in counterfactual if clauses), but actually I think it's really just simple past tense. Consider...

If you did the crime you must do the time

You did the crime so you must do the time

In those examples, I can't see that switching from "if" to "so" changes the "verb form" of "did". All it does is change the utterance from a "conditional sentence" to a "statement".

If it were [to have been?!] cast in the past subjunctive, it would be something more like...

If the Mayans were wrong to have ended the calendar on Dec 20...