LSAT Explanation PT 36, S3, Q13: While it was once believed that

LSAT Question Stem

The argument is vulnerable to criticism because it ignores the possibility that 

Logical Reasoning Question Type

This is a Flaw question. 

Correct Answer

The correct answer to this question is A. 

LSAT Question Complete Explanation

Let's first analyze the argument in the passage. The passage states that while it was once believed that psychotherapy was appropriate for both neuroses and psychoses, it is now known that psychoses are best treated with biochemical (medicinal) means. The author concludes that this is conclusive evidence that psychoses, unlike neuroses, are caused by purely organic conditions, such as abnormal brain chemistry or brain malformations.

The structure of the argument is as follows:

Premise: Psychoses are best treated by biochemical means.

Conclusion: Psychoses are caused by purely organic conditions.

An "Evaluate" question for this argument could be: "Can environmental factors contribute to or cause the organic conditions that result in psychoses?"

Now, let's discuss the question type and answer choices. This is a Flaw question, which asks us to identify the vulnerability in the argument.

a) The organic conditions that result in psychoses can be caused or exacerbated by environmental factors: This answer choice points out the possibility that environmental factors may still play a role in causing or worsening the organic conditions that lead to psychoses. This weakens the conclusion that psychoses are caused by purely organic conditions, making it the correct answer.

b) The symptoms of mental disturbance caused by purely organic factors can be alleviated with medicine: This answer choice does not address the argument's vulnerability, as it only restates that medicine can help treat mental disturbances caused by organic factors. It does not challenge the conclusion that psychoses are caused by purely organic conditions.

c) Organic illnesses that are nonpsychological in nature may be treatable without using biochemical methods: This answer choice is out of scope, as the argument is focused on psychological illnesses (neuroses and psychoses) and their causes. It does not address the vulnerability in the argument.

d) The nature of any medical condition can be inferred from the nature of the treatment that cures that condition: This answer choice does not point out a flaw in the argument. Instead, it suggests a general principle that could potentially strengthen the argument. However, it does not address the possibility of environmental factors playing a role in causing psychoses.

e) Organic factors having little to do with brain chemistry may be at least partially responsible for neuroses: This answer choice is irrelevant to the argument's conclusion about psychoses. It discusses neuroses, which are not the focus of the conclusion. It does not address the vulnerability in the argument.

In summary, the correct answer is (a), as it points out the possibility that environmental factors may still play a role in causing or worsening the organic conditions that lead to psychoses, which weakens the conclusion that psychoses are caused by purely organic conditions.