Critical Reasoning

Scientist: My research indicates that children who engage in impulsive behavior similar to adult thrill-seeking
behavior are twice as likely as other children to have a gene variant that increases sensitivity to dopamine. From
this, I conclude that there is a causal relationship between this gene variant and an inclination toward thrillseeking
behavior. Which one of the following, if true, most calls into question the scientist's
argument?
A. Many impulsive adults are not unusually sensitive to dopamine.
B. It is not possible to reliably distinguish impulsive behavior from other behavior.
C. Children are often described by adults as engaging in thrill-seeking behavior simply because they act impulsively.
D. Many people exhibit behavioral tendencies as adults that they did not exhibit as children.
E. The gene variant studied by the scientist is correlated with other types of behavior in addition to thrill-seeking
behavior.


[spoiler]It is not possible to reliably distinguish impulsive behavior from other behavior.
If this were true, it would weaken the argument. If it's not possible to reliably distinguish impulsive behavior, the
research is far less likely to be accurate. If the research is not accurate, it doesn't provide compelling support for the
conclusion. (B) is correct.[/spoiler]

But B is questioning the validity of the premise. it says premise itself is wrong. we are supposed to accept facts as true always..
so how can b be right?
and I still dont understand why A is wrong

A is wrong because it speaks about MANY adults and not ALL.

Answer B does question the validity of the premise and it is possible that the argument weakening question will be based on such an approach. In this question the correct answer shows that supposedly factual information (= a premise) is merely an assumption and might be untrue.

Thanks Kasia
But having ALL in A would make it destroy the conclusion . weaken questions are supposed to only make the conclusion less likely and since A says many adults are impulsive but still are insensitive to dopamine, it indicates, many adults dont have that gene. For the conclusion to be valid, all adults should have that gene.
So A does weaken.

And aren't we supposed to accepts facts/premises as true always and never question them?

But B is questioning the validity of the premise. it says premise itself is wrong. we are supposed to accept facts as true always..
so how can b be right?
and I still dont understand why A is wrong

Usually, in the weaken/strengthen questions, we attack the assumptions. But the correct answers might attack the premise also, especially when a weak premise is presented.

Look at the question stem: Which one of the following, if true, most calls into question the scientist's argument? So, we need to take the options as true and see how it affects the argument.

Option B says It is not possible to reliably distinguish impulsive behavior from other behavior. So, it is essentially saying that Scientist might have mistaken some behavior for impulsive behavior. If this were true, it would certainly weaken the argument.

Scientist: X causes Y.
Option B: It is not possible to distinguish between Y and Z.
>> So, it might well be the case that X causes Z, and scientist has mistaken Z for Y.

Eg: Scientist: "I have seen a pink colored Cobra in Antarctica. So,I hypothize that there is some connection between Antarctic conditions and skin color of Cobra".
The argument will be severely weakened if it is true that Scientist is colorblind.

Hi vk,
But from what I have learnt from various sources, we should never question the premise. this makes me perplexed

it doesn say premise is wrong
it weakens the underlying meaning of the sentence and hence the conclusion..

sachindia wrote:Scientist: My research indicates that children who engage in impulsive behavior similar to adult thrill-seeking
behavior are twice as likely as other children to have a gene variant that increases sensitivity to dopamine. From
this, I conclude that there is a causal relationship between this gene variant and an inclination toward thrillseeking
behavior. Which one of the following, if true, most calls into question the scientist's
argument?
A. Many impulsive adults are not unusually sensitive to dopamine.
B. It is not possible to reliably distinguish impulsive behavior from other behavior.
C. Children are often described by adults as engaging in thrill-seeking behavior simply because they act impulsively.
D. Many people exhibit behavioral tendencies as adults that they did not exhibit as children.
E. The gene variant studied by the scientist is correlated with other types of behavior in addition to thrill-seeking
behavior.

The scientist ASSUMES that there is a link between the gene variant and impulsive behavior because HIS RESEARCH INDICATES that there is a link.
What his research indicates is not a fact.
The OA here BREAKS THE LINK between the gene variant and impulsive behavior.
It is not possible to reliably distinguish impulsive behavior from other behavior.
Thus, the link between the gene variant and impulsive behavior is weakened.

As for answer choice A, beware the word MANY.
The scientist does not claim that ALL children who engage in impulsive behavior have the gene variant; his research indicates only that these children are TWICE AS LIKELY to have the gene variant.
Thus, even if there are MANY exceptions, the argument is unaffected.

Hi Mitch,

The scientist ASSUMES that there is a link between the gene variant and impulsive behavior because HIS RESEARCH INDICATES that there is a link.
What his research indicates is not a fact.
The OA here BREAKS THE LINK between the gene variant and impulsive behavior.
It is not possible to reliably distinguish impulsive behavior from other behavior.
Thus, the link between the gene variant and impulsive behavior is weakened.

I don't understand how the OA breaks the conclusion. OA says its not possible to differentiate between the behaviours, specifically impulsive from others whereas the causal link is between gene variant and impulsive behaviour.

As for answer choice A, beware the word MANY.
The scientist does not claim that ALL children who engage in impulsive behavior have the gene variant; his research indicates only that these children are TWICE AS LIKELY to have the gene variant.
Thus, even if there are MANY exceptions, the argument is unaffected.

This is great. Many thanks..!!

sachindia wrote:Hi Mitch,

I don't understand how the OA breaks the conclusion. OA says its not possible to differentiate between the behaviours, specifically impulsive from others whereas the causal link is between gene variant and impulsive behaviour.

The scientist links the gene variant to the behavior that he OBSERVED in the children.
He has deemed this behavior IMPULSIVE.
But the OA indicates that impulsive behavior cannot be reliably distinguished from OTHER TYPES OF BEHAVIOR.
Thus, the scientist cannot prove that the observed behavior was in fact IMPULSIVE, weakening the link between the gene variant and impulsive behavior.