LSAT Explanation PT 43, S3, Q9: Most lecturers who are effective teachers

LSAT Question Stem

Which one of the following statements follows logically from the statements above? 

Logical Reasoning Question Type

This is a Must Be True question. 

Correct Answer

The correct answer to this question is A. 

LSAT Question Complete Explanation

Let's first understand the passage and then analyze the question type. The passage states:

1. Most lecturers who are effective teachers are eccentric.

2. Some noneccentric lecturers are very effective teachers.

3. Every effective teacher is a good communicator.

The question type here is Must Be True (MBT), which means we need to find the answer choice that logically follows from the given statements.

Now, let's break down the statements using formal logic notation:

1. Most effective teacher lecturers (ET) are eccentric (ECC): ET -> ECC

2. Some noneccentric lecturers (NECC) are effective teachers (ET): NECC -> ET

3. Every effective teacher (ET) is a good communicator (GC): ET -> GC

Now, let's analyze the answer choices:

a) Some good communicators are eccentric.

We can combine the inherent "some" inference from statement 1 (ECC -> ET) with statement 3 (ET -> GC) to get: ECC -> GC. This means that some good communicators are eccentric. So, this answer choice is correct.

b) All good communicators are effective teachers.

This is a mistaken reversal of statement 3 (ET -> GC). We cannot conclude that all good communicators are effective teachers, so this answer choice is incorrect.

c) Some lecturers who are not effective teachers are not eccentric.

We cannot combine any of the given statements to determine the eccentricity of lecturers who are not effective teachers. Thus, this answer choice is unsupported by the passage.

d) Most lecturers who are good communicators are eccentric.

We cannot substitute "good communicator" for "effective teacher" in statement 1 because they are not logically equivalent. Being a good communicator does not necessarily make one an effective teacher. This answer choice is incorrect.

e) Some noneccentric lecturers are effective teachers but are not good communicators.

According to statement 3, it is impossible for someone to be an effective teacher without being a good communicator. This answer choice contradicts one of the premises, so it cannot be correct.

In conclusion, the correct answer is (a) Some good communicators are eccentric, as it logically follows from the given statements in the passage.