LSAT Question Stem

Each of the following, if true, weakens the argument EXCEPT: 

Logical Reasoning Question Type

This is a Weaken question. 

Correct Answer

The correct answer to this question is A. 

LSAT Question Complete Explanation

The argument in the passage is structured as follows:

Premise: Clinical depression correlates with decreased left lobe activity, whereas lack of depression correlates with increased left lobe activity.

Conclusion: Frontal lobe activity affects one's general disposition.

This argument assumes a causal relationship between frontal lobe activity and general disposition based on a correlation. However, correlation does not necessarily imply causation. To better understand this, consider a simple example: Imagine that there is a correlation between ice cream sales and the number of people wearing sunglasses. This does not mean that ice cream sales cause people to wear sunglasses or vice versa. It is more likely that both are influenced by a third factor, such as sunny weather.

An "Evaluate" question for this argument could be: "Is there any other factor that might influence both frontal lobe activity and general disposition?"

Now, let's analyze the answer choices for the Weaken question:

a) Many drugs prescribed to combat clinical depression act by causing increased left lobe activity.

This answer choice does not weaken the argument, as it provides evidence that supports the correlation between frontal lobe activity and general disposition. It suggests that increasing left lobe activity can help alleviate depression, which is consistent with the argument's conclusion. This is the correct answer.

b) Excessive sleep, a typical consequence of clinical depression, is known to suppress left lobe activity.

This answer choice weakens the argument by suggesting that excessive sleep, rather than frontal lobe activity, could be responsible for the correlation between depression and decreased left lobe activity. This introduces an alternative explanation for the observed correlation.

c) Frontal lobe activity is not subject to variation the way general disposition is.

This answer choice weakens the argument by suggesting that frontal lobe activity cannot directly cause variations in mood since it does not vary in the same way. If frontal lobe activity remains constant while mood changes, it is unlikely that frontal lobe activity is the cause of mood variations.

d) Earlier studies indicated that frontal lobe activity and emotive states are both caused by activity in the brain's limbic system.

This answer choice weakens the argument by introducing a third factor, the brain's limbic system, which could be responsible for both frontal lobe activity and emotive states. This suggests that the observed correlation between frontal lobe activity and general disposition may not be due to a direct causal relationship.

e) Social interaction of the kind not engaged in by most clinically depressed people is known to stimulate left lobe activity.

This answer choice weakens the argument by suggesting that the causal relationship might be reversed: social interaction (related to general disposition) could influence left lobe activity, rather than the other way around.

In conclusion, the correct answer to this Weaken question is A, as it does not undermine the argument's conclusion or the relationship between the premises and the conclusion.