Q: Here’s a sentence written by a student of mine at Rutgers: “If I had have known, I would have changed my forecast.” Ouch! But if I’m honest, I can hear myself using a contracted version, “If I’d have known, I would have changed my forecast.” What’s going on here?
A: When people say (or write) “If I’d have known,” they’re contracting “I would,” not “I had.” That’s why your student’s uncontracted sentence sounds especially jarring to you. However, modern usage guides consider both sentences wrong.
The error here is using “If I would have known” (or “If I’d have known”) instead of “If I had known.” The construction calls for the past perfect tense in that first clause: “If I had known, I would have changed my forecast.”
Merriam-Webster’s Dictionary of English Usage says this use of “would have” has been cited as an error since at least the 1920s. It adds that the “usage is characteristic of informal speech, in which it may often occur in a contracted form.”
“Our evidence indicates that it does not occur in standard writing that finds its way into print,” Merriam-Webster’s says, “but it is notorious in student writing and therefore a staple of college handbooks even today.”
A few years ago, we ran a blog entry that touched on this error. But for your convenience, we’ll summarize the part that relates to your question.
A common error with “would” is illustrated in the sentence “If I would have shown him, he would have believed me.”
This is an error in the sequence of tenses. The challenge here is to juggle two tenses in one “if” sentence, and in this case the first clause calls for the past perfect tense (“had shown”).
Here’s a fairly simple explanation of how the tenses should work together:
(1) If the first verb is in the simple present, the second should be in the simple future: “If I show him, he will believe me.”
(2) If the first verb is in the simple past, the second should be in the simple conditional: “If I showed him, he would believe me.”
(3) If the first verb is in the past perfect, the second should be in the conditional perfect: “If I had shown him, he would have believed me.”
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