Knew vs Had Known


" If John knew about the problem last year, he would have taken care of it"


I believe the correct sentence should have, "If John had known..." because of the "would have" construction in the subordinate clause. However, I don't see a real change in meaning between 'knew' and 'had known'.

asked Mar 02 '11 at 17:34 PCN New member

2 answers


The technical difference between "knew" and "had known" is a matter of verb tense, and I can't explain it because I don't know it myself. All I can tell you on that matter is that "had known" and "would have" agree in tense. I can explain the difference in what these two forms imply, though.


"If John knew about the problem, he would take care of it."
In order to use "knew," everything in the sentence must agree with that tense. It implies that John's knowing (or lack of knowing) is taking place at this very moment, and continues-- that is, John still doesn't know about the problem.


"If John knew about the problem [right now], he would take care of it [but he doesn't know about it, so he can't take care of it]."


"If John had known about the problem last year, he would have taken care of it."

The tense of this sentence agrees. It implies that John didn't know about the problem last year, but he does now.


"If John had known about the problem last year, he would have taken care of it [but he didn't know about it back then, so he has to take care of it now]."

link answered Mar 02 '11 at 20:20 Collane Ramsey Expert

Great answer, Collane! Thanks for contributing. KimberlyMar 03 '11 at 13:05

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Technically your first example represents the second conditional and the other the third conditional (which is best choice). Both are also known as "Counterfactual assertions" (see Bloom, 1981) meaning they begin with a premise that is implied to be FALSE. Ex: If I knew French, I could read the works of Voltaire. This implies that I do not know French.   


If you are looking into the past with hindight bias, then use the third conditional:

- If John had known about the problem last year, he would've taken care of it


If you hypothesize about a non-present scenario, then use the second conitional:

- If John knew (subjunctive mood) about the problem (omit "last year"), he would take care of it


However, if you talk about a more immediate and realistic present situation it might be better to use the first conditional:

- If John knows about the problem, he will take care of it



link comment edited Jun 12 '11 at 11:05 Gabedude Contributor

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