GMAT CR: Can You Weaken This Argument?
The three most frequent GMAT CR question types are Find the Assumption, Strengthen the Argument, and Weaken the Argument. If you can master these three types, you should do well on CR.
Try this problem from the free questions that come with the GMATPrep software and then well talk about how Weaken questions work!
A museum has been offered an undocumented statue, supposedly Greek and from the sixth century B.C. Possibly the status is genuine but undocumented because it was recently unearthed or because it has been privately owned. However, an ancient surface usually has uneven weathering, whereas the surface of this statue has the uniform quality characteristically produced by a chemical bath used by forgers to imitate a weathered surface. Therefore, the statue is probably a forgery.Which of the following, if true, most seriously weakens the argument?
(A) Museums can accept a recently unearthed statue only with valid export documentation from its country of origin.
(B) The subjects pose and other aspects of the subjects treatment exhibit all the most common features of Greek statues of the sixth century B.C.
(C) The chemical bath that forgers use was at one time used by dealers and collectors to remove the splotchy surface appearance of genuinely ancient sculptures.
(D) Museum officials believe that forgers have no technique that can convincingly simulate the patchy weathering characteristic of the surfaces of ancient sculptures.
(E) An allegedly Roman sculpture with a uniform surface similar to that of the statue being offered to the museum was recently shown to be a forgery.
Got your answer? Before we dive into the solution, what are you supposed to be doing for Weaken questions in general? (I cant actually hear your answer, of course. But say it out loud anyway. Youll be able to hear whether you are confident in your explanation.)
If youre going to do well on Critical Reasoning, then youve got to be able to articulate the goal for the particular sub-type of CR problem that youre facing right now.
Weaken the Argument questions are asking you to find an answer choice that makes the conclusion of the argument at least a little less likely to be valid. (The correct answer usually wont completely kill the argument.)
Now, in order to find this type of answer, you have to be able to recognize that you have a Weaken question in the first place. How do you know?
First, whenever the question stem contains the language if true (or a synonym), then you know you have one of three question types: Strengthen, Weaken, or Explain a Discrepancy. Among those three, Weaken questions will also include language asking which choice weakens or undermines the argument. Or it might ask which answer choice casts doubt on the argument. You may also see other synonyms, all of which would get at the idea of weakening the argument.
The if true language is an important signal, by the way: it tells you that the correct answer is expected to contain new information. Be very careful about crossing off answers because you think theyre out of scope; people will sometimes do so too aggressively and cross off the correct answer.
Its also useful to know that the most common trap on Weaken questions is a reverse logic trap: the answer actually strengthens the argument instead of weakening it.
Okay, lets dive into this problem!
Step 1: Identify the Question
The question stem contains if true and weakens. Boom: this is a Weaken question.
As soon as you identify the question as a Weaken question, you now know that you have an Assumption Family question, so the argument will contain a conclusion, as well as some unstated assumptions. Itll be important for you to deconstruct that full argument arc (from premises to conclusion).
Step 2: Deconstruct the Argument
Whats the structure of the argument?
The statue is undocumented, and only supposedly has certain characteristics. In other words, its unclear whether this statue is authentic. There are two possible reasons it could be genuine even though it is undocumented: it might have been found only very recently, or it might have been owned privately, so never documented for museum purposes.
BUT! The statue also has a uniform surface, which is unusual for an authentic statue. A chemical bath could have produced this uniform qualityand chemical baths are used by forgers to try to fool people into thinking something is authentic.
Therefore, the author concludes, the statue is probably a forgery.
Heres what my notes looked like, taken as I read the argument:
Are any assumptions in the argument jumping out at you? If so, note them down. Attacking an assumption would weaken the argument, so that may help you to find the correct answer.
I noted a possible weakness in [brackets]. The argument is assuming that a chemical bath was used to make the surface uniform, but maybe theres some other cause for the uniformity of the surface.
Step 3: State the Goal
On Weaken questions, the goal is to find an answer that makes the argument somewhat less likely to be valid. In this case, we need something that makes it somewhat less likely that the statue is probably forged.
Step 4: Work from Wrong to Right
All right, lets start evaluating those answer choices!
(A) Museums can accept a recently unearthed statue only with valid export documentation from its country of origin.
This has to do with whether a museum will accept a statue, not with whether this particular statue is forged. Eliminate.
(B) The subjects pose and other aspects of the subjects treatment exhibit all the most common features of Greek statues of the sixth century B.C.
If the statue is typical of Greek statues of the 6th century, then maybe that means its more likely to be real?
Wait a second. A forger would also be likely to make sure that his faked statue matches the common features of that era. So, actually, this evidence could also support the idea that its a forgery. Eliminate.
(C) The chemical bath that forgers use was at one time used by dealers and collectors to remove the splotchy surface appearance of genuinely ancient sculptures.
So the chemical bath isnt used only by forgers. It was also (once) used for genuine artifacts. This slightly weakens the author's conclusion that the statue is forged; maybe this statue actually is genuine and was just in a private collection for a long time. When it was first found, perhaps the chemical bath was used to make it look better.
This one isnt quite what I brainstormed, but its the same idea: theres some other, legitimate reason why the chemical bath might have been used. It wasnt necessarily used by forgers.
(D) Museum officials believe that forgers have no technique that can convincingly simulate the patchy weathering characteristic of the surfaces of ancient sculptures.
The statue in question does not have the patchy appearance, so this piece of information doesnt impact the authors argument.
(E) An allegedly Roman sculpture with a uniform surface similar to that of the statue being offered to the museum was recently shown to be a forgery.
If another statue with a similar surface was forged, then maybe this one is too!
Oh, wait. If so, that would strengthen the argument. The question asked us to weaken. This is a common trap, called a reversal trap. (Also, note that technically this one doesnt even strengthen the argument. The fact that some other artifact was faked doesnt indicate anything concrete about the specific statue in question.)
The correct answer is (C). Its the only one that weakens the argument. It does so by weakening the premise about the chemical bath: while its still true, as the argument said, that forgers may use the chemical bath, its also true that legitimate dealers and collectors have used the process to clean artifacts.
What did you learn on this problem? Come up with your own takeaways before you read mine below.
Key Takeaways for Weaken Problems:
(1) Know how to identify the question type (if true + weaken, undermine, cast doubt) and what youre trying to do: find a choice that makes the argument at least a little less likely to be valid.
(2) Understand how the argument works: what are the premises and what is the authors main claim? What are the weaknesses in the argument? In this case, the author concludes that the statue is probably a forgery but leaves holes regarding the use of the chemical bath.
(3) Watch out for trap answers. The most common trap answer on a Weaken question will strengthen the argument instead. (The reverse is true on Strengthen questions: trap answers will weaken.) Answer (B) was also tricky in this problem, because one interpretation could lead to the idea that it weakens the argument. The problem was that the answer choice could also be interpreted in a way that would strengthen the argument.
* GMATPrep questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.