LR Question 12 Explanation
QUESTION TEXT: People who say that Dooney County is flat are…
QUESTION TYPE: Necessary Assumption
CONCLUSION: Dooney county is not flat.
REASONING: On flat land, farmers won’t build terraces with the intention of preventing soil erosion. Yet Dooney county farms have many terraces.
ANALYSIS: Are there other reasons that people build terraces, apart from preventing soil erosion? Maybe terraces look nice.
The author only proved that people won’t build terraces in order to prevent soil erosion. They might build terraces for other reasons.
___________
- This doesn’t matter, since one of the premises says that people don’t build terraces to prevent erosion (no matter the cause).
- CORRECT. The argument only proved that no flatlanders build terraces in order to prevent erosion. If none of the terraces were built to prevent erosion, then the argument has a problem.
- We don’t care whether terraces work. We only care why they were built.
- We don’t care whether soil erosion is a problem. Whether or not terraces would work to prevent erosion, we know that no flatlanders do build them in order to prevent erosion.
- Non-farm terraces don’t matter. The argument’s evidence only relates to terraces on farmland.
More Resources for Necessary Assumption Questions
- Negations Article: Learn about negations on the LSAT.
- Conditional Reasoning Article: Learn about conditional statements.
- Negations Drill: Practice your negation skills.
- LR Diagrams Guide: Learn how to draw LR diagrams.
- Intro to Conditional Reasoning: Learn conditional reasoning basics.
- Intro Course lesson: This intro course lesson covers Necessary Assumption questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers necessary assumption questions.
This is so confusing…. I am really stuck on this :(
From the stimulus, we only know that farmers whose land is flat don’t build terraces to prevent erosion. But the stimulus didn’t rule out the idea that terraces might be built for other reasons. Maybe the farmers like sitting outside, and that’s why there’s terraces on farms in Dooney County.
So to prove that Dooney County is not flat (the conclusion), we need to know that these terraces were built to prevent soil erosion. That’s what B tells us.
To check a Necessary Assumption answer, we can apply the negation test. To negate an answer, you just take the opposite. The reason the negation test works is if you take the opposite of an answer choice, and that opposite destroys the argument, then your answer is a Necessary Assumption (because if the opposite were true, the argument wouldn’t work, so the answer is necessary for the argument to work).
The negation of B is: There are terraces on farms in Dooney County which were NOT build to prevent soil erosion.
If this is true, then the argument doesn’t work. If there are terraces that were built for other reasons than soil erosion, then maybe Dooney County is flat, and the conclusion doesn’t work.
Hope that helps! Let me know if you have further questions.