LSAT 105 | Section 1 | Logical Reasoning: Q23

LR Question 23 Explanation

QUESTION TEXT: Deep tillage is even more deleterious to the world’s …

QUESTION TYPE: Necessary Assumption

CONCLUSION: Farmers who till deeply should incorporate no-till methods instead.

REASONING: Deep tillage is 10x more likely to erode topsoil than no-till methods.

ANALYSIS: The argument suggests that farmers have no alternative but to switch to no-till methods in order to avoid deep tillage.

But what if there are methods that allow you to till a little without tilling deeply? Then the conclusion wouldn’t follow.

So we need an assumption that shows that no-till methods are the only option.

___________

1. We’re talking about what they should do, not what they want to do.
   Negation: Topsoil erosion makes farmers want to till more deeply.
2. Even if all deep tillage caused the same amount of erosion, the argument would still stand. So we don’t need this assumption.
   Negation: The depth of tilling does not affect the susceptibility to topsoil erosion.
3. CORRECT. If there were another viable option, then farmers would not need to switch to no-till – they could switch to this alternative method instead.
   Negation: Tilling by a method other than deep tillage is a viable option.
4. Cost doesn’t matter to the argument.
   Negation: The most expensive farming methods do not employ techniques other than deep tillage.
5. The argument doesn’t depend on no-till providing better aeration, just that it’s an alternative to deep tillage.
   Negation: On average, top-soil that is no-tilled is not more aerated than topsoil that is tilled deeply.