Arguments and Assumptions on the GMAT

Isolating the Nerve Center of an Argument

Arguments in real life can take a number of forms, but arguments on GMAT Critical Reasoning questions are relatively formulaic.  The typical GMAT argument has three parts:

1) Premise: the starting point of deductions; often, agreement to this is assumed.

2) Conclusion: what the author wants you to believe by the end of the argument

3) Assumption: the unstated link between premise and conclusion.

Although unstated, the assumption is the nerve center of the argument, the linchpin holding the whole thing together.


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Strengthening and Weakening Arguments

Assumptions are crucial in understanding an argument, and because of this, they play a large role in two major Critical Reasoning question types.  Some questions ask you: “Which would most strengthen the argument?”  The most powerful way to strengthen an argument is to validate its assumption.  Other questions, perhaps the single most common on Critical Reasoning, ask: “Which of the following would most weaken the argument?”  The most devastating attack on an argument is the denial of its assumption — without the assumption, the link between the premise and the conclusion is severed.

Think Broadly

When identifying assumptions, one crucial point to remember: assumptions are most often general statements, not specific statements.  If my premise is “Fred has quality A,” and my conclusion is “Therefore, Fred has quality B,” then the assumption is not going to involve Fred at all.  The assumption would be something like “most/all folks who have quality A also have quality B.”  In trying to identify the assumption, it can helpful to remember that you can omit any specific people/places/items mentioned.


Identifying the Assumption

Consider, first of all, this relatively ludicrous argument:

Hawaii is a place with beautiful scenery.  Therefore, people there must have trouble concentrating for any length of time at all. 

The premise: Hawaii is a place with beautiful scenery — we can safely assume that at least 99 out of a hundred people would agree with that!  The wacky conclusion: people there can’t concentrate.  The assumption must provide a link.

Hawaii is the specific, so drop that.  The premise has to do with “place with beautiful scenery”, and the conclusion has to with “trouble concentrating”, so just put those together with a strong logical connection: “People in places with beautiful scenery generally have trouble concentrating.”  There! That’s a possible way to state the assumption.  It would most strengthen this laughable argument if one could somehow provide data or evidence supporting this assumption.  It would shatter this poor argument if we could cite data or evidence that directly contradicts the assumption.


Now, consider a somewhat more GMAT-worthy argument:

Of all the companies in the steel industry in the last six months, only Amalgamated Ferric Industry (AFI) has tripled their advertising expenditures.  No other steel company has increased advertising nearly that much.Therefore, in the coming months, we should see AFI gaining new customers at a rate that outpaces all its competitors. 

Dropping the specifics, the premise is about increasing spending on advertising, and the conclusion is: more new customers.  An assumption would link these.  A very broad assumption: “companies that increase what they spend on advertising generally see an increase in new customers.”  A slightly more specific assumption: “when companies in the steel industry increase advertising, this generally results in more new customers.”  This is a relatively poor argument, and if we were asked for a statement to weaken it, the best choice would be something that zeroed in on the assumption.  For example: studies of companies in the steel industry show little correlation between advertising dollars and new customers.  That strikes right at the nerve center of the argument, obliterating it.  That’s exactly what this kind of GMAT Critical Reasoning is asking you to do.

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On the real GMAT, if you can anticipate what the best answer choice will look like, that will make it much easier to find!


Here are two Critical Reasoning practice questions to practice your assumption skills:

  1. Professor Hernandez’s book
  2. Twentieth-century Art

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20 Responses to Arguments and Assumptions on the GMAT

  1. Rose January 7, 2017 at 7:25 pm #

    Dear Mike,
    How can you tell which is a premise and which is an assumption? I am a bit confused of the difference. Much appreciated!

    • Magoosh Test Prep Expert
      Magoosh Test Prep Expert January 8, 2017 at 4:04 pm #

      Hi Rose,

      Think about it this way: the premises are the facts of the argument. They help us get to the conclusion, but we also need a link between them. Those links are the assumptions — things that may or may not be true, but which are assumed to be true by the author of the argument.

      The premise here is that the company increased advertising expenditures. This is a fact about the company: it already happened. The increased customers has not yet happened — that is a conclusion based on the following assumptions:

      1. (broadly) companies that increase what they spend on advertising generally see an increase in new customers
      2. (specifically) when companies in the steel industry increase advertising, this generally results in more new customers

      The author assumes these to be true. If they are indeed true, then the conclusion makes sense. If they are in fact false, then the conclusion may be wrong.

      • Jess February 1, 2017 at 9:36 am #

        The fact that the customers will increase wouldn’t be the conclusion made by the author? Since it is his consideration. I am confused between what is assumed and what is concluded.
        And by the way, great way of explaining the answers.

        • Magoosh Test Prep Expert
          Magoosh Test Prep Expert February 1, 2017 at 11:00 am #

          Hi Jess,

          You’re right! I’ve edited the comment in response to Rose to make all this more clear.

  2. Valentina November 16, 2016 at 1:36 pm #

    This post was a real eye opener. I have been doing CR questions blind before reading this. Extremely helpful

  3. Rishabh September 13, 2015 at 11:48 am #

    Hi Mike,

    I have a doubt: Can assumptions have new piece of information?


  4. siddhartha November 11, 2013 at 7:37 pm #

    Dear Mike

    It is well written a piece of document. I run a small company in India and trying my luck in HBS next year, certainly, your work has given me a fair insight of the stuff. Pl guide me for more practice questions further on all topics.

    Thanks buddy

  5. Abhinav Avunoori December 22, 2012 at 1:31 am #

    Thanks formaking this a cakewalk! !

    • Mike MᶜGarry
      Mike December 22, 2012 at 1:37 pm #

      You are quite welcome. Best of luck to you.
      Mike 🙂

  6. KM June 12, 2012 at 1:04 pm #

    Thanks for directing me to the url, Mike !

    • Mike MᶜGarry
      Mike June 12, 2012 at 3:10 pm #

      You are quite welcome. Best of luck to you, and let us know if you have any further questions.
      Mike 🙂

  7. KM June 12, 2012 at 10:18 am #

    Thanks for the list!
    Could you please mention OG-12 problems?

  8. KM June 12, 2012 at 8:59 am #

    Hi Mike,

    Could you please refer to some OG problems that can be solved with these strategies?

    • Mike MᶜGarry
      Mike June 12, 2012 at 9:39 am #

      Dear KM — in OG 13, CR #21, #41, #46, #48, #75, and #77 are a few.
      Mike 🙂

  9. KM June 6, 2012 at 1:49 pm #


    The real GMAT strategy!


    • Mike MᶜGarry
      Mike June 6, 2012 at 1:56 pm #

      Thank you for your effusive praise! Best of luck to you!
      Mike 🙂

  10. Ravi Sankar Vemuri April 28, 2012 at 2:41 am #

    Emphasis on assumption, “the nerve centre” is very good. The given examples instil the GMAT-taker to think about the unspecified but important thing “The Assumption”.

    • Mike MᶜGarry
      Mike April 30, 2012 at 11:58 am #

      Thank you for your kind words, sir. You are obviously an astute reader, and your praise is well-appreciated. Best of luck to you.
      Mike 🙂

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