LSAT Explanation PT 37, S4, Q13: When several of a dermatologist's patients

LSAT Question Stem

Each of the following, if true, provides additional support for the dermatologist's diagnosis EXCEPT: 

Logical Reasoning Question Type

This is a Strengthen question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

First, let's analyze the argument in the passage. The dermatologist observes that several patients have a rash on one side of their faces and suspects that the cause is some kind of external contact. The dermatologist then finds out that the rash occurred on the side of the face where the telephone was held and concludes that the rash was caused by prolonged contact with telephones. In this argument, the premise is the observation of the rash on one side of the patients' faces and its correlation with the side where the telephone was held. The conclusion is that the rash was caused by prolonged contact with telephones.

To make this more relatable, let's use a simple example: Imagine you notice that people who frequently wear a specific brand of sunglasses develop red marks on their noses. You then conclude that the sunglasses are causing the red marks due to prolonged contact with the nose.

Now, let's create an "Evaluate" question for this argument: "Is there any other factor that could have caused the rash on the patients' faces besides prolonged contact with telephones?"

The question type for this problem is Strengthen, and we are asked to find an answer choice that does not provide additional support for the dermatologist's diagnosis.

a) This answer choice supports the conclusion by suggesting that some people might be allergic to the materials used in phones, which could cause the rash.

b) This answer choice strengthens the argument by eliminating the possibility that other devices could have caused the one-sided rash, further supporting the conclusion that telephones are the cause.

c) This answer choice strengthens the argument by showing that most patients had frequent contact with phones, increasing the likelihood that the rash was caused by prolonged contact with telephones.

d) This is the correct answer choice. The fact that most people use a phone does not help to establish a direct link between phone usage and the rash observed, so it does not support the dermatologist's diagnosis.

e) This answer choice strengthens the argument by suggesting that an increase in phone usage could explain the new appearance of rashes, further supporting the conclusion that the rash was caused by prolonged contact with telephones.