Can someone help?
"Dave killed Peter."
Dave asked Susan, "why was Peter here?"
Susan said, "Maybe he would have told you if you hadn't have killed him."
Would there have been any difference if she had said "Maybe he would have told you if you hadn't killed him"?
According to my understanding, Susan wants to emphasise the fact that Peter would have told Dave why he was here if Dave hadn't killed him first. Right? Meaning, Susan thinks Dave would still kill him anyway, before or after Peter told Dave why he was here.
Best Answer
In his book The Syntactic Phenomena of English, McCawley argues that in a position requiring a non-finite form, a past tense is shifted to perfect "have", and that multiple "have"s are shifted to just a single "have". According to this analysis, in your example "if you hadn't have killed him", there are 3 logical past tenses, "if you Past Past n't Past kill him", the second two get changed to "have": "if you Past have n't have killed him", then the multiple occurrences of "have" are reduced to just one: "if you Past have n't killed him". Then, with the realization of "Past have" as "had", we wind up with "if you hadn't killed him".
It's an interesting and rather intricate analysis. However that may be, in the standard dialect that McCawley describes, you can't wind up with the perfect of a perfect, because one of the two perfect "have"s is lost by an arbitrary adjustment, in order to fit the logic of constructions into the restrictive morphological system of English.