LSAT Explanation PT 19, S4, Q1: Three-year-old Sara and her playmate Michael

LSAT Question Stem

The reasoning in the argument is flawed because the argument 

Logical Reasoning Question Type

This is a Flaw question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

Let's break down the argument in the passage:

1. Sara and Michael are both ill and have the same symptoms (Premise).

2. They play together every afternoon (Premise).

3. Sara probably has the same illness as Michael (Conclusion 1).

4. Michael definitely does not have a streptococcal infection (Premise).

5. The illness that Sara has is definitely not a streptococcal infection (Conclusion 2).

The argument starts by concluding that Sara probably has the same illness as Michael, based on their symptoms and their interaction. Then, it uses this conclusion to make a stronger claim about Sara's illness, stating that she definitely does not have a streptococcal infection because Michael doesn't have one. The problem here is that the argument moves from a probability to a certainty, which is a logical flaw.

An "Evaluate" question for this argument could be: "Is it certain that Sara and Michael have the same illness?"

Now, let's analyze the answer choices:

a) The argument does not presuppose that Sara does not have streptococcal infection; it uses the premises to reach that conclusion through flawed reasoning.

b) This answer choice is not relevant because the argument is not about cause and effect. The focus is on determining Sara's illness, not its cause.

c) The argument doesn't mention the severity of streptococcal infections. It's only concerned with whether or not Sara has the illness.

d) This is the correct answer choice. The argument treats the probability that Sara has the same illness as Michael as if it establishes the certainty of the conclusion that Sara does not have streptococcal infection. This is a logical flaw.

e) This answer choice is not relevant because the argument is not making a general claim based on particular examples. It's making a specific claim about Sara's illness based on her symptoms and interaction with Michael.