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GMAT Sentence Correction: If vs. Whether

“I don’t know if you will find this post helpful”

Do you spot the error in the preceding sentence?  This error is common in casual spoken English, but it will cost you on the GMAT Sentence Correction.  In that sentence, the word “if” is incorrect: it should be replaced by the word “whether.”


When to use “if”

The word “if” is used for clauses that specify conditions or speculate on something hypothetical.

1.) Condition: “If you finish your peas, you can have dessert.”

2.) Hypothetical: “If I regularly ate my vegetables, I probably would be healthier.”


In formal logic, the clause following the “if” clause would begin with the word “then”: that’s perfectly acceptable grammatically, but not at all necessary.  For example, in both of those sentence, the word “then” could be inserted right after the comma, and would add a bit of emphasis to the logical relationship, if that were something that needed underscoring.

The last clause of the previous paragraph highlights a particular category of conditional statements, those using the subjunctive.  For more on the subjunctive mood, see this post.  The GMAT loves “if”-clauses involving the subjunctive.


When to use “whether”

The word “whether” is a relative pronoun, which means it introduces a relative clause.  A “whether” clause is always about the uncertainty in a choice or alternative, and the clause itself may stand apart from the sentence, the way an “if” clause does, or may act as a noun.  When it stands apart, it is like an “if” clause in which the definite causal nature has been replaced with uncertainty or irrelevance.  When it acts as a noun, the clause may act as the subject of the sentence, or as the object of an epistemological verb (to know, to wonder, etc.)  or a volitional verb (to care, to prefer, etc.)


Stands apart:

3.) Whether you study French or Spanish, you will encounter an unfamiliar language in Japan.

4.) Whether or not I get the raise, I am going to buy that new car.


Notice, in either of those: if we removed the uncertainty of the choice, we could replace the word whether with the word “if” to get a more definitive conditional statement.  Without making those changes, the word “if” would be wrong.


Subject of sentence:

5.) Whether you like jazz will influence your opinion of this new club.

6.) Whether I walk on her left or right side matters a great deal to her.


Object of an epistemological or volitional verb:

7.) I don’t know whether there is intelligent life elsewhere in the Universe.

8.) He doesn’t care whether you serve broccoli or Brussels sprouts with dinner.


In sentence #5-8, the word “if” would be 100% incorrect.   The GMAT Sentence Correction loves to test that particular mistake.


Whether . . . or not

The word “whether” implies a choice, at least a pair of alternatives.  Sometimes that choice is made explicit (as in sentences #6 and #8), and sometimes it is implicit (as in sentences #5 & #7).  When the choice is implicit, is it grammatically correct to add the words “or not” after whether?

When the “whether” clause acts as a noun, the words “or not” add absolutely nothing to the sentence. Consider:


5a.) Whether you like jazz will influence your opinion of this new club.

5b.) Whether or not you like jazz will influence your opinion of this new club.


The meaning of both sentences is exactly the same.  The second sentence adds two more words that contribute zilch to the overall meaning of the sentence.  What is GMAC’s opinion of tossing in extra words that lengthen the sentence and contribute bupkis to the meaning?  As you may well guess, they frown on these.  Don’t expect to see “whether or not” in any correct GMAT SC answer choice when the clause is used as a noun.

When the clause stands apart, as in sentences #3 & #4, that’s another matter.  In that construction, the alternative must be made explicit.  In #3 there already was an explicit comparison of the two languages, but in #4 we absolutely must include the words “or not” after the word “whether”: the grammatical construction demands it.  This is the only case in which the words “whether or not” could be correct on GMAT sentence correction.

Whether or not you like it, knowing the correct use of “whether” and “if” is important for GMAT Sentence Correction.  If you can master these distinctions, you will perform well on a question that that befuddles many.

Two relevant SC questions in the GMAT Official Guide, which appear as:

a.) #34 & #75 in OG12e, and

b.) #34 & #78 in OG13e

About the Author

Mike McGarry is a Content Developer for Magoosh with over 20 years of teaching experience and a BS in Physics and an MA in Religion, both from Harvard. He enjoys hitting foosballs into orbit, and despite having no obvious cranial deficiency, he insists on rooting for the NY Mets. Follow him on Google+!

18 Responses to GMAT Sentence Correction: If vs. Whether

  1. Sudipt August 20, 2014 at 2:48 am #

    Hi Mike,

    Been following your content on this website and have found it extremely useful.

    It puts all the important things forward in a very simple manner, something I have not found anywhere else on the web.

    Just a question – does Magoosh have online classes for the Verbal section of GMAT ?



    • Mike
      Mike August 20, 2014 at 9:57 am #

      Dear Sudipt,
      Yes, absolutely! We have a full set of Verbal video lessons, including a recently revised series on GMAT SC, and each practice question has its own video explanation — these accelerate the learning process with immediate feedback. If you click on the ad at the top “Learn More about Magoosh GMAT Prep”, you will be led to our plans page.
      Mike :-)

  2. zish July 15, 2014 at 5:35 am #

    Hi mIke

    What i got from this is that when Whether is used as a subordinate clause ,we cannot replace it with “if”, and when whether clause is used as a subject or object of verbs then it is replaceable by ‘”if”. Am i correct?

    • Mike
      Mike July 15, 2014 at 2:52 pm #

      Dear Zish,
      I’m happy to respond. :-) Unfortunately, my friend, that is not entirely correct. First of all, both “whether” and “if” begin subordinate clauses, so that is not a good way to distinguish them. Further, a clause that used as a subject is a substantive clause, which is one category of subordinate clauses, and these definitely need to begin with “whether” — an “if” clause can NEVER be the subject of a sentence. For the most part, what distinguishes the correct use of “if” from the correct use of “whether” is not grammar but LOGIC. You need to understand in depth the logical distinctions discussed in this article.
      Does all this make sense?
      Mike :-)

      • Zish July 15, 2014 at 3:55 pm #

        Thanks mike

        • Mike
          Mike July 15, 2014 at 4:02 pm #

          Dear Zish,
          You are more than welcome. :-) Best of luck to you!
          Mike :-)

  3. Jay June 9, 2014 at 8:16 pm #

    Hi Mike,
    I’ve been following your blog posts lately. They have been tremendously helpful.
    I have a question from the post. You mentioned that the words “or not” will add no meaning to “whether” that acts as a noun. (Example given is “whether (or not) you like Jazz….”). Does the same concept apply toward “whether” that acts as an object of volition or epistemological verb? I assume that will be the case, but I just wanted to be sure… Thank you.

    • Mike
      Mike June 10, 2014 at 10:14 am #

      I’m happy to respond. :-) In spoken language, in colloquial English, the “or not” would often be used for rhetorical clarity — “I don’t know whether or you are planning to come to my party.” In the formal writing of the GMAT SC, this will not happen. The “or not” will be wrong 100% of the time on the GMAT.
      Does this make sense?
      Mike :-)

      • Jay June 10, 2014 at 4:31 pm #


        Totally. Thanks!

        • Mike
          Mike June 11, 2014 at 10:11 am #

          Dear Jay,
          My friend, you are quite welcome. Best of luck to you.
          Mike :-)

  4. Confuse Mind August 16, 2012 at 7:44 pm #

    Just one clarification-

    By stand apart – you mean 2 complete clauses are connected, right?

    • Mike
      Mike August 17, 2012 at 3:03 pm #

      I’m not sure what you mean be “connected.” By “stand apart”, I mean the “whether” clause is separated from the rest of the sentence by a comma, and what follows is a complete independent clause. Unlike the subsequent examples, the whether clause is not playing a role (subject or direct object) in the main independent clause of the sentence. Are we saying the same things?
      Mike :-)

  5. Abhi June 8, 2012 at 10:15 pm #

    Sorry, I don’t understand how the following sentence cannot have “if”:
    “I don’t know whether there is intelligent life elsewhere in the Universe.”

    Replacing “whether” with “if” also sounds correct:
    “I don’t know if there is intelligent life elsewhere in the Universe”

    • Mike
      Mike June 10, 2012 at 4:10 pm #

      Abhi: the trouble is — this is a *very* common error in spoken English. The mistake is more common than the correct construction in spoken English. This is why the incorrect construction, with “if”, *sounds* correct. It’s not correct. This is also why the GMAT loves testing this concept, because when people don’t know the grammar and just rely on what sounds natural, they will be wrong. Does that make sense?
      Mike :)

      • Abhi June 21, 2012 at 7:07 pm #

        Thanks, Mike. Yes, I realized I have been making this mistake myself, while speaking, since a long time now. Good to clear it up.

        • Mike
          Mike June 22, 2012 at 1:12 am #

          I’m glad I was able to help. Best of luck to you.
          Mike :)

  6. Komal May 29, 2012 at 10:56 am #

    It was great help, as I had always confused with “Whether or not” issue. Now I understand why “Whether or not ” is correct. Thank you.

    • Mike
      Mike May 29, 2012 at 2:55 pm #

      I’m glad you found this helpful. Let us know if you have any further questions.
      Mike :)

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