LSAT 146 | Section 3 | Logical Reasoning: Q25

LR Question 25 Explanation

QUESTION TEXT: At Morris University this semester, most of the…

QUESTION TYPE: Flawed Parallel Reasoning

CONCLUSION: There must be more sociology major than psychology majors who are taking Introduction to Social Psychology.

REASONING: Most sociology majors are taking the class. Most psychology majors are not.

ANALYSIS: This argument leaves off relative numbers. It’s possible there are 10 sociology majors at the school, and 5000 psychology majors. In that case, “not most” psychology majors could still be far larger than “most sociology majors”.

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1. Like answer D, this switches between “owns” and “displays”. The original just stuck to one category, “students”. This answer does make a numerical error, but it also makes a category error, and that’s why it’s wrong.
2. This is a different error. The argument assumes the two choices are in opposition. But it’s possible 90% of residents are for road spending, and 89% want park spending.
    
   Some choices are exclusive. You can be in NYC or Chicago. But it’s possible to spend money on both priorities, so there’s no reason to assume either choice has less than 50% support.
    
   The original argument didn’t make a false exclusion mistake.
3. This is a different flaw. It’s assuming that what’s true in a small area is true in a larger area.
    
   Example of answer with same terms: There are more sociology majors in this class. So there must be more sociology majors at the university.
4. CORRECT. This also makes the error of ignoring relative numbers. There could be 100 vegetables at Valley Foods Co-op, and 10,000 vegetables at the Jumbo supermarket. In that case, “not most” of the vegetables at Jumbo Supermarket could be more than “most” of the vegetables at Valley foods.
    
   Example: Most at valley = 80. “Not most” at Jumbo = 2000. 2000 is more than 80.
5. This answer jumps between terms: “photos”, and “houses/condos on sale.”
    
   In the original, there was no such jump. The comparison was between students and students.