Here’s a sentence that can teach us a little about the mystery of time: I just talked with tech support, but they didn’t have an answer and they had escalated the ticket to Level II support. Something is not quite right here, and the problem lies in what is called the sequence of tenses, the way in which the tenses of the three verbs relate to one another. This can be a tricky business, but we can at least make ourselves more aware of the subtleties that language can convey.
We have here one sentence with three clauses (I just talked, they didn’t have, and they had escalated), and we would say that this is a compound sentence because the two words joining the three clauses (but and and) are coordinating conjunctions. So far so good. If we next identify the tense of each verb, we find that talked is simple past, didn’t have is also simple past, and had escalated is past perfect. We remember that English has six tenses, three called simple and three called perfect, and we might remember, too, that the past perfect works under a certain very strict mandate: it can only refer to a time that was before a time in the past we have already referred to. Or, to say that in more technically precise language: to a time anterior to another past time.
So let’s look at the way the three tenses in this sentence work together. To say I just talked means that I did something before the present moment when I am telling you I just talked with tech support. This is obvious, but it’s important to be aware of, because one of the mysteries of time is that it can be absolute or relative, that is, there is time according to the clock and time according to another moment of time within a sentence. We have agreed that talked is the simple past tense, and we would call that an absolute tense, because it is referring to real time, the time of the speaker of the sentence within the world of the sentence (what is so aptly called the universe of discourse). The next verb, didn’t have, is also simple past (in negative form), and so it too is referring absolutely to a time in the past from the perspective of the moment of saying the sentence. The first two verbs, then, measure their distance, so to speak, from the moment the speaker, the subject I, was making known what happened in his call to tech support.
But what about the third verb, had escalated? We have identified this verb as the past perfect and we have noted that it is used to refer to a time before another past time. So that would mean that the tech team had escalated the ticket before they didn’t have an answer, because we can rightly assume that this third clause of this compound sentence is working in an orderly way from the perspective of the immediately preceding clause (compound sentences are meant to unfold nicely like this, particularly when the conjunctions are clearly named, as is the case with the word and here). But what is not the case here is meaningful logic. It does not make sense to say that the tech people had escalated the ticket before they didn’t have an answer. What does make sense is to say that two events occurred before the time the subject is saying he spoke with tech support. That first clause is the focusing moment of all that goes on in the sentence, and that is the point of reference from which the other two tenses are to be measured.
What makes this difficult (and it is) is the fact that the past perfect tense can only properly refer to another past tense—we could call it a past-past tense. So which of the other two past tense verbs in this sentence should it refer to? Neither. All this sentence is saying is that three things happened in the past—a time past in relation to the present moment of speaking or writing the sentence: I talked, they didn’t have, and (as a result) they escalated. Tech support did not escalate the ticket before they didn’t have an answer, and they didn’t escalate it before the subject, I, talked with them.
A subtle problem—just like our minds.