PrepTest 149
[lcid:3694] Prep Test 149 LSAT — Logical Reasoning — S3
Logical reasoning
Question prompt
Decreased reliance on fossil
Remaining source text redacted.
Why the credited answer is right
Credited answer: D
The notes below walk through why it fits the stem and how to eliminate the rest.
Question Type
Flawed Parallel Reasoning Questions
Answer choices
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AIf we end poverty Remaining source text redacted.
Why choice A is not credited
Incorrect. End poverty → End hunger
End unemployment → End poverty . . . and we're out. These two premises do chain together, unlike the premises of the stimulus. -
BDaily exercise guarantees good Remaining source text redacted.
Why choice B is not credited
Incorrect. Without diagramming these out, you should be able to tell that the first two statements—the premises—will chain together, and thus we can eliminate this answer. If you weren't able to track that without diagrammign it out, that's fine! Keep practicing conditional logic until you can do that and you'll be a lot faster on both the LR and LG sections. -
CGoing to college is Remaining source text redacted.
Why choice C is not credited
Incorrect. Professional job → College
College → Graduate high school . . . and we're out, as these statements chain together. -
DKeeping good teachers is Remaining source text redacted.
Why choice D matches the stem
Correct. Argument or Facts:
Argument
Valid or Flawed:
Flawed
Question Type:
Flawed Parallel Reasoning
Stimulus Summary:
Halt global warming → Decreased reliance on fossil fuels
Economic incentives for alternative energy → Decreased reliance on fossil fuels
Therefore Ð Halt global warming → Economic incentives for alternative energy
Answer Anticipation:
This argument features a lot of conditional logic, so we should anticipate a conditional logic flaw. After diagramming the statements out, we can see that the conclusion is drawn by chaining the two conditional premises together. However, those premises can't be chained together, as they share a necessary condition.
Looking at the argument, we could determine that the specific flaw is that the author treats the second conditional as if it were reversed, but we don't need to come to that specific conclusion since we can find an answer that matches the general pattern here, thus guaranteeing that it'll have the same flaw:
A → B
C → B
Therefore Ð A → C
Answer Explanation:
Improve education → Keep good teachers
Teacher salaries improved → Keep good teachers
Therefore Ð Improve education → Teacher salaries improved
This is the same argument structure relying on the same illegal reversal of a premise, so this is the correct answer.
Key Takeaway:
When a Flawed/Parallel Reasoning question has strong conditional elements, being able to eliminate answers without diagramming them out because you can spot where overlapping terms are in the statements is a very useful skill to have. It's not necessary for doing well on the exam.
But . . .
Being able to eliminate 1 or 2 answers here without diagramming them out because you can tell the conditionals will chain together where the stimulus was flawed because the premises didn't chain would save a good chunk of time. Practice conditional logic! -
EPreventing abuse of prescription Remaining source text redacted.
Why choice E is not credited
Incorrect. Prevent prescription drug abuse → Expand drug education
Expand drug education . . . and we're out, as these premises chain together.
What this tests
Discussion
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