LSAT 154 | Section 4 | Logical Reasoning: Q7

LR Question 7 Explanation

QUESTION TEXT: Late blight is a disease affecting tomato plants that causes…

QUESTION TYPE: Parallel Flaw

CONCLUSION: Late blight disease is caused by a plant’s copper deficiency.

REASONING: Applying a copper solution to the plants is an effective treatment.

ANALYSIS: This argument is basically saying “since copper is the cure, then a deficiency in copper must be the cause.” This is like saying: “Pain medication helps with arthritis. Thus, not taking pain medication causes arthritis.” This example obviously sounds wrong. The correct answer choice will mirror this flaw.

___________

1. This says, “since X works, then even more X is better”. Eliminate.
2. This says, “since it’s caused by lack of X, thus X is the solution”.
3. This is wrong since malnutrition needs to be part of the solution to follow the stimulus’ pattern of reasoning.
4. CORRECT. This parallels the stimulus’ structure of “since X is the cure, then lack of X must be the problem”.
5. This says, “since lack of X causes the problem, then having X will not cause the problem”, which is an illegal negation and doesn’t appear in our stimulus.

Recap: The question begins with “Late blight is a disease affecting tomato plants that causes”. It is a Flawed Parallel Reasoning question. Learn how to master LSAT Flawed Parallel questions on the LSAT Logical Reasoning question types page.