LSAT Explanation PT 36, S3, Q12: Vague laws set vague limits on

LSAT Question Stem

The conclusion follows logically if which one of the following is assumed? 

Logical Reasoning Question Type

This is a Sufficient Assumption question. 

Correct Answer

The correct answer to this question is A. 

LSAT Question Complete Explanation

The question type for this problem is Sufficient Assumption, which asks us to identify an assumption that would make the conclusion logically follow from the premises.

Let's first analyze the argument in the passage:

Premise: Vague laws set vague limits on people's freedom.

Premise: Vague limits on people's freedom make it impossible for them to know for certain whether their actions are legal.

Conclusion: Under vague laws, people cannot feel secure.

The argument's structure can be represented as:

Premises: Vague laws -> Vague limits -> Cannot know actions are legal

Conclusion: Vague laws -> Cannot feel secure

Our task is to find an assumption that connects "Cannot know actions are legal" to "Cannot feel secure." Let's evaluate each answer choice:

a) People can feel secure only if they know for certain whether their actions are legal.

This answer choice is the contrapositive of the assumption we need (Cannot know actions are legal -> Cannot feel secure), making it the correct answer.

b) If people do not know for certain whether their actions are legal, then they might not feel secure.

This answer choice is incorrect because it introduces uncertainty with the term "might not," while the conclusion states "cannot feel secure."

c) If people know for certain whether their actions are legal, they can feel secure.

This answer choice is the Mistaken Negation of the correct answer. It does not provide the necessary connection between "Cannot know actions are legal" and "Cannot feel secure."

d) People can feel secure if they are governed by laws that are not vague.

This answer choice is a Mistaken Negation of the conclusion and does not provide the necessary connection between the premises and the conclusion.

e) Only people who feel secure can know for certain whether their actions are legal.

This answer choice is also the Mistaken Negation of the correct answer and does not provide the necessary connection between the premises and the conclusion.

In conclusion, the correct answer is (a) because it provides the necessary assumption to connect the premises and the conclusion, making the argument valid.