LR Question 5 Explanation
QUESTION TEXT: A store was vandalized repeatedly over a six-month period…
QUESTION TYPE: Weaken
CONCLUSION: The friend concluded that there was bright lighting installed around the store.
REASONING: A store was frequently vandalized over six months. The owner mentioned to a friend that bright lighting around a store may reduce vandalism. Three months passed, and there was no more vandalism.
ANALYSIS: The friend is making a pretty tenuous assumption. They need to assume a few things:
- The owner did install the lights.
- The lights 100% reduced vandalism, despite normally only somewhat reducing it.
- No other cause also reduced vandalism.
Four answers violate one of these assumptions. The other answer merely is consistent with them. So, note that the correct answer doesn’t have to prove the friend right! It only has to not weaken his case.
___________
- Police patrols are an alternate cause; #3 in the list above. This weaken the friend’s argument.
- This makes the friend’s argument virtually impossible. There’s no way that lights were installed (#1 in the list above).
- CORRECT. This answer is ambivalent. It makes it sound like the owner installed lights and that those lights also protect neighbouring stores.
But it’s also possible that the store owner did something else, like hiring a team of night watchmen. Who knows? This answer doesn’t prove the friend right. However, unlike the other answers, it doesn’t prove him wrong, so that makes it the correct answer.
….It really would be nice though to actually ask the owner “hey, did you install lights”. - Like B, this answer makes the friend’s assumptions virtually impossible. If the lights weren’t installed (#1 in the list above), then obviously new lights couldn’t be the reason that the vandalism stopped.
- #3 in the list above. A guard dog is an alternate reason that vandalism may decline. So this provides an alternate explanation to lights.
Recap: The question begins with “A store was vandalized repeatedly over a six-month period”. It is a Weaken question. Learn how to master LSAT Weaken questions on the LSAT Logical Reasoning question types page.
More Resources for Weaken Questions
- Intro Course lesson: This intro course lesson covers Weaken questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers weaken questions.
To add to my previous comment:
In other words, I think even if we negated it and said, “There are other causes that also reduced vandalism,” the friend’s conclusion would still be valid?
In fact, the negation “there are *OTHER* causes that *ALSO* reduced” even seems to suggest that lightning is one of the causes?
Responding to both your comments here. Imagine you step outside and see the sidewalk is wet and you conclude “It must have rained”. This conclusion isn’t just saying rain could have contributed – it’s effectively implying that rain was the explanation. If a sprinkler had been running or a water main had broken, then assuming rain was the reason would be questionable.
Similarly, the friend sees that vandalism stopped and concludes “Bright lights must have been installed”. But this conclusion isn’t just saying that lights could have played a role, it’s asserting that lights were the explanation. That implicitly assumes no other cause could fully account for the drop in vandalism. If an alternative cause existed, then the friend’s reasoning falls apart.
So while the friend doesn’t explicitly state assumption #3 in Graeme’s list, their conclusion depends on it. If the friend believed something else could explain the change, they wouldn’t have assumed that lights MUST have been installed. Hopefully that makes sense!
I don’t understand part of the analysis written for this question. Why would the friend have to assume that NO OTHER cause also reduced vandalism?
I understand that if we discover other causes, it would weaken the friend’s conclusion. But still, the friend doesn’t have to assume that no other cause reduced vandalism, does he? Because the friend only concluded that: “bright lighting had been installed.” The friend’s conclusion seems consistent with the fact that there are other coexisting causes?