LSAT 82, Logical Reasoning I, Q16, LSATHacks

QUESTION TEXT: Most pet owners who take allergy medication are allergic…

QUESTION TYPE: Flawed Parallel Reasoning

CONCLUSION: If Chuck gets a pet allergy he will probably take allergy medication.

Diagram: Pet allergy (most)–> take allergy medication

Note: On the LSAT, words such as “likely” and “probably” mean the same thing as “most”, so this argument’s conclusion is a “most” statement.

REASONING: Chuck owns a pet dog. Most pet owners who take allergy medication are allergic to pets.

Diagram: Take allergy medication (most)–> allergic to pets

ANALYSIS: This argument incorrectly reverses a “most” statement. We know this is true: take allergy med (most)–> allergic to pets

The argument incorrectly reverses that to this: allergic to pets (most)–> take allergy medication

You can never reverse a “most” statement. It’s possible many people have mild pet allergies which aren’t serious enough for them to take medication.

So, to parallel this, look for an answer with two “most” statements, then draw them, and pick the answer where the “most” statement is reversed. Only three answers have two most statements: A, B and E. C and D say “unlikely” which aren’t really most statements for the purposes of paralleling the argument.

Note that there’s one other element: the left side of the “most” statement is talking about “pet owners”. So the stimulus tells us that Chuck is a pet owner in order to try to show he meets the criteria. This doesn’t help us on this question: every answer talks about “Anastasia” in the same way. But, on a different question, this form of making a “most” statement for a single person could be a factor in making a parallel argument.

Note that the LSAT has many synonyms for most: likely, probably, usually, etc.

___________

1. The stimulus had a bad argument, but this answer has a good argument. It gives one “most” statement: Taken to Acme (most)–> electrical problems.
   Then the author applies Anastasia’s car to the left side of the most statement: since most customers who take their car to Acme have electrical problems, Anastasia’s car likely does too!

   The stimulus, by contrast, incorrectly applied Chuck’s case to the right side of the most statement.

2. CORRECT. The statement here is “Taken to acme (most)–> electrical problems”. The argument then incorrectly reverses it to say “electrical problems (most)–> take to acme”. This is the exact same reversal the original argument made, so this is correct.
3. This is a bad argument, but it isn’t because of a reversal. Instead, the flaw the argument makes is analogous to this one: most people taken the the hospital have colds. So, if you cut off your arm, you probably won’t go to the hospital.
   The error? Assuming the likelihood of you taking an action is based on the most common reasons for that action. (sorry, it’s sort of an abstract error. Because cutting off your arm is not common, you’re unlikely to seek treatment, according to this error)
4. This is actually identical in logical meaning to C. The word “not” actually isn’t logically significant. Both answers have the form “A (most)–> B, therefore not A, probably not B”. In C, A = no electrical problems, in D, A = electrical problems. But otherwise the two answers are identical. (Assuming, in D, that Anastasia could have some other reason to bring her car in. Automotive shops may do many things, including routine checkups)
5. Answers A and B are the most compelling answers, and in both of those, Anastasia has taken her car to the auto shop. The only question is why she did so.
   But this answer is strange, it doesn’t do that. Instead, it says that there are reasonable odds Anastasia will go to Acme every time the car has electrical problems.
   That’s crazy! This answer isn’t saying Anastasia will go there most times. Instead, it’s saying she’s likely to go every time.

   So she’ll go there….if there’s a fire in the automotive shop? If the automotive shop has flooded? If it has been overrun by wolves? This answer is saying Anastasia will go there no matter the cost.

   We also know nothing about this automotive shop! It might be in Australia and Anastasia might live in Europe. Why would Anastasia always take her car to a random auto shop on another continent? This answer doesn’t say she’s been there before. This answer’s flaw is rather different than the flaw in the stimulus.

Recap: The question begins with “Most pet owners who take allergy medication are allergic”. It is a Flawed Parallel Reasoning question. Learn more about LSAT Flawed Parallel questions in our guide to LSAT Logical Reasoning question types.

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