Give it your best guess
‘Identify the assumption’ type questions in the critical reasoning section require you to apply logical negation skills to guess the right answer
Over the past few weeks, we have analysed the question types you can expect in the critical reasoning (CR) section of the GMAT. Today, let’s look at ‘identify the assumption’ type questions— which, along with strengthen and weaken the argument, form the three most important question types in CR.Identify the Assumption
These questions are typically worded as follows:
“The argument in the passage depends on which of the following assumptions?”
“The conclusion above is based on which of the following assumptions?”
“Which of the following is an assumption made in drawing the conclusion in the argument?”
“The argument above assumes that …”
“The conclusion of the argument cannot be true unless which of the following is true?”
Defined within the framework of this exam, an assumption is that component that has to be true for the argument to be valid. In our day-today life, we make a lot of assumptions. When you call a colleague and ask her to send the BTX file by email, you assume the colleague knows what BTX means and that she knows your email address.
Consider a simple example of an assumption in this argument: Ram walked into the class and he was drenched with water. It must be raining.
Which of these two choices should be the assumption of the
argument? A. Rain is the only reason as to why a person gets drenched
with water. B. Rain is just one of the reasons as to why a person gets
drenched with water.
Option B is a tempting choice. After all, don’t we all know that rain is only one of the reasons as to why a person gets completely drenched. Somebody could have thrown a bucket of water at Ram, or the poor fellow could have walked below a ladder.
However, the issue is that this form of reasoning is completely dependent on our own general knowledge of the way the world works, without any significance to the argument itself!
Important lesson: CR is not a test of your GK. Look at the conclusion in the argument. The conclusion was: It must be raining. The conclusion is not saying: It COULD be raining. If the conclusion was: It MUST be raining, then the underlying assumption is the one mentioned in choice A. In order for the argument to be true, the author is assuming that rain is the only reason as to why a person gets, or this person has got drenched. Hence, the answer is A.
There is a way to tackle these questions. The correct answer will pass the negate-and-attack test. Here’s how you can conduct this test:
Step 1: Logically negate the answer choice.
Step 2: If the logical negation of a certain answer choice attacks the argument and weakens it, then that is indeed the correct answer.
Let’s go back to our example. Sitting in the exam hall, let’s assume that you thought that the answer was B, which is incorrect. Let’s see if this methodology helps realise this.
The first step would be to logically negate the answer choice. The answer choice is: Rain is just one of the reasons as to why a person completely gets drenched in water. The logical negation of this choice is: Rain is the ONLY reason as to why a person completely gets drenched. This seems to be completely in agreement with the conclusion that: It must be raining. The methodology says that the logical negation of the correct answer will attack the argument and weaken it. Since the logical negation of B neither attacks the argument nor weakens it, we can safely conclude that B is NOT the correct answer.
This methodology might sound tedious at first, but with practice, it is a foolproof way to handle problems based on assumptions.
On the other hand, let us check whether this methodology helps in narrowing down A as the correct answer. The first step would be to logically negate the answer choice A. The logical negation of: Rain is the only reason as to why a person gets completely drenched with water, is: Rain is just one of the reasons as to why a person gets drenched in water. This logical negation of answer choice A is completely in opposition to the conclusion: It must be raining. The logical negation might have been in agreement with a conclusion that said: It COULD be raining. Since the logical negation of answer choice A attacks the argument and weakens it, we can conclude that A is the correct answer.
Article courtesy: Naveenan Ramachandran, director, Taurus Education (naveenan@4gmat.com)
Option B is a tempting choice. After all, don’t we all know that rain is only one of the reasons as to why a person gets completely drenched. Somebody could have thrown a bucket of water at Ram, or the poor fellow could have walked below a ladder.
However, the issue is that this form of reasoning is completely dependent on our own general knowledge of the way the world works, without any significance to the argument itself!
Important lesson: CR is not a test of your GK. Look at the conclusion in the argument. The conclusion was: It must be raining. The conclusion is not saying: It COULD be raining. If the conclusion was: It MUST be raining, then the underlying assumption is the one mentioned in choice A. In order for the argument to be true, the author is assuming that rain is the only reason as to why a person gets, or this person has got drenched. Hence, the answer is A.
There is a way to tackle these questions. The correct answer will pass the negate-and-attack test. Here’s how you can conduct this test:
Step 1: Logically negate the answer choice.
Step 2: If the logical negation of a certain answer choice attacks the argument and weakens it, then that is indeed the correct answer.
Let’s go back to our example. Sitting in the exam hall, let’s assume that you thought that the answer was B, which is incorrect. Let’s see if this methodology helps realise this.
The first step would be to logically negate the answer choice. The answer choice is: Rain is just one of the reasons as to why a person completely gets drenched in water. The logical negation of this choice is: Rain is the ONLY reason as to why a person completely gets drenched. This seems to be completely in agreement with the conclusion that: It must be raining. The methodology says that the logical negation of the correct answer will attack the argument and weaken it. Since the logical negation of B neither attacks the argument nor weakens it, we can safely conclude that B is NOT the correct answer.
This methodology might sound tedious at first, but with practice, it is a foolproof way to handle problems based on assumptions.
On the other hand, let us check whether this methodology helps in narrowing down A as the correct answer. The first step would be to logically negate the answer choice A. The logical negation of: Rain is the only reason as to why a person gets completely drenched with water, is: Rain is just one of the reasons as to why a person gets drenched in water. This logical negation of answer choice A is completely in opposition to the conclusion: It must be raining. The logical negation might have been in agreement with a conclusion that said: It COULD be raining. Since the logical negation of answer choice A attacks the argument and weakens it, we can conclude that A is the correct answer.
Article courtesy: Naveenan Ramachandran, director, Taurus Education (naveenan@4gmat.com)
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