Critical Reasoning

Scientist: Cross-sections of stalactites - calcite formations deposited on cave ceilings by seeping water - can reveal annual variations in rainfall in particular areas over hundreds and thousands of years. We often found that when-according to these cross-sections-drought occurred in a particular area, it coincided with the collapse of an ancient society in that area. I hypothesize that drought reduced agricultural productivity in these areas, thereby leaving these societies without the resources needed to handle internal stresses and external threats.

Which of the following, if true, would most weaken the support for the scientist's hypothesis?

A. Many droughts indicated in the cross-sections of stalactites do not correspond with the collapse of a society in that area.

B. Information from the cross-sections of stalactites alone cannot reveal the level of agricultural output in an area at a particular time.

C. Most of the societies that collapsed during droughts did so when internal power struggles coincided with military raids from neighboring societies.

D. Most of the societies that collapsed during droughts maintained large stockpiles of food and water at the time of their collapse.

E. Information from stalactites also suggests that the collapse of some societies coincided with periods of abnormally high rainfall.

D

Hi Experts,

Can you please suggest why B is incorrect?

It is better to summarize what the scientist's hypothesis is so that weaken only that.

The scientist's hypothesis is given in the last line of the argument -

Drought --> reduces Agricultural Productivity --> No resources to handle stresses and threats --> Collapse

A - has no relationship to the hypothesis mentioned above. The hypothesis only talks about how droughts lead to societal collapse. Stalactites have nothing to do with this.
Also, notice that the argument states - "we often found ...". (this implies then that such a pattern sometimes did not occur). So, this answer option does not give any new information. Eliminate.
B - The hypothesis is about how drought leads to collapse of societies. Information from stalactites has nothing to do with this.
C - Kind of strengthens the argument. States that internal struggles and external raids during droughts indeed lead to collapse.
D - Correct answer. This breaks the causal chain shown above. We can no longer say that droughts lead to "no resources to handle internal stresses or external threats" since such societies maintained large stockpiles of food and water.
E - We are concerned only with droughts, how droughts lead to societal collapse. Other conditions, which might lead to societal collapse, are not relevant to the scientist's hypothesis.

Hi Crackverbal,

I have a question. Can I say that B is incorrect because per author, the below statement is a fact/always true.

We often found that when-according to these cross-sections-drought occurred in a particular area, it coincided with the collapse of an ancient society in that area.

Now, if such is the case then I have one more doubt:

In a weaken passage, the stimulus is under suspicion and the option statements are taken as true. My question is can I eliminate an option belonging to the weaken type where new info is allowed by saying that this is against the facts given in the passage in that case?

Also wanted to confirm when you say the stimulus is under suspicion what do you mean - you are not going to believe author's line of reasoning and authors conclusion on face value? or even the facts are doubtful?

B is incorrect because it has nothing to do with the scientist's hypothesis -
You must only be concerned with this portion - "I hypothesize that ..."
Whether cross-sections of stalactites alone are sufficient or more information is needed is not relevant to the scientist's hypothesis