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I know that the following sentence is valid.

•If I had known about the matter, I would have told you.

This means that at a point in the past, I did not know about the matter and I didn't/couldn't tell you (because I didn't even know).

Does the next sentence work?

•If I knew about the matter, I would have told you by now.

Let's say you have a friend who wants to know about everything. She or he asks you if you currently know about a particular matter, which you don't know anything about. But you know that you would have told your friend if you actually knew about that.

In the above sentence, the if-clause uses a past tense because it is about the present. However, the main clause uses past perfect because this is about the past as in you would have done it.

To me this makes sense and in this particular situation, saying the below sentence sounds weird:

•If I had known about the matter, I would have told you.

because you are referring to whether you know about the matter now, but not in the past.

John Lawler
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jun
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  • Yes, that sentence works in that situation. – Kate Bunting Oct 20 '21 at 10:30
  • Strictly speaking, *If I would have known about the matter, I would have told you.* Except in nearly all cases the *if-* clause features contracted *If I'd have known...* - which I personally "unpack" as *If I had have known...*, regardless of what pedantic grammarians and linguists tll me. – FumbleFingers Oct 20 '21 at 10:55

1 Answers1

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Both sentences are fine.

In

if I had known about the matter, I would have told you

works because there are two times, the telling (in the past) and the knowing (prior to the telling).

And

If I knew about the matter, I would have told you by now

works because the words "by now" indicate that the telling might be as late as the present, while the knowing is in the past.

What doesn't work quite as well to my ears is

If I knew about the matter, I would have told you,

because that sounds to me like the knowing is in the present, but the telling is in the past, which doesn't conform with common sense. But the grammar that native English speakers is conditionals in quite varied, so I'm sure some native English speakers will think that sentence is fine.

Peter Shor
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