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Chatting with a colleague we came a cross a dilemma (as we are not English native), which of the following sentences are wrong? Why?

  1. If I knew everything, I'd be a genius.
  2. If I know everything, I'd be a genius.
  3. if I know everything, I'm a genius.

The 2nd should be wrong, as with the present I should use either the future or the present, in fact the 3rd seems to me correct, in fact the rule is:

The Zero Conditional is used for actions that are always true when the conditions are satisfied.

So to form this particular condition I use this form:

If + Present Simple, + Present Simple

Am I wrong?

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afaik the first one is correct (like "if i were you i'd..."), however English is not my first language – www0z0k Jan 31 '11 at 14:01
I endorse Kosmonaut's answer; but I cannot work out what you mean by "The Zero Conditional". – Colin Fine Jan 31 '11 at 18:15
“It is clear that a division of conditionals into the zero, first, second, and third categories does not adequately reflect actual usage.” —from “If only it were true: the problem with the four conditionals”, Christian Jones and Daniel Waller, ELT Journal 65:1 pp 24–32 (2011), Oxford University Press, doi: 10.1093/elt/ccp101. – tchrist Jan 24 '15 at 14:39
up vote 11 down vote accepted

Sentences 1 and 3 are both correct.

Sentence 1 is a counterfactual conditional sentence, and sentence 3 is a factual conditional sentence.


In these constructions, the condition clause expresses a condition the truth of which is unverified.


In these constructions, the condition clause expresses a condition that is known to be false, or presented as unlikely.

Sentence 2 is indeed wrong because it is mixing the two in an incompatible way.

share|improve this answer
Thanks a lot, now it's clear. – tmow Jan 31 '11 at 16:09

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