LR Question 19 Explanation
QUESTION TEXT: Doctor: Medical researchers recently examined a large…
QUESTION TYPE: Flawed Reasoning
CONCLUSION: Slipped or bulging disks can’t lead to back pain.
REASONING: Some people with no back pain have slipped or bulging disks.
ANALYSIS: The LSAT often treats causes as absolute. Either something always leads to an effect, or it never does.
That’s not how things work in real life, and this question acknowledges that. Maybe slipped disks cause back pain 30% of the time.
So they haven’t caused pain to those in the study, but they might cause pain to other people. Something can occasionally be a cause even if it isn’t always a cause.
___________
- This says something might be a sufficient condition even if it’s not necessary. But slipped disks aren’t sufficient or necessary, so this answer is irrelevant.
- CORRECT. Something can be a cause even if it isn’t a sufficient cause. Slipped and bulged disks may cause pain in some other cases.
- This is different.
Example of flaw: The lights work when there is no hurricane, so clearly they’ll work when there is a hurricane. - The doctor didn’t say that half of the population has slipped or bulged disks. Something can’t be a flaw unless it happens.
- This is different. This says that slipped disks may be correlated with pain even if they’re not the cause of pain.
Recap: The question begins with “Doctor: Medical researchers recently examined”. It is a Flawed Reasoning question. To practice more Flawed Reasoning questions, have a look at the LSAT Questions by Type page.
More Resources for Flaw Questions
- Flaw drills: Use these to practice making examples of abstract flaws.
- Intro Course lesson: This intro course lesson covers Flaw questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers flaw questions.
Could you provide an example of B? How could slipping/bulging disks still be a causal factor even though they are not sufficient in themselves?
Think about rain and traffic accidents: rain alone isn’t always sufficient to cause an accident (most people drive safely in the rain). But rain can still be a causal factor, since it makes accidents more likely when combined with other things, e.g. speeding or poor tires.
In the same way, bulging or slipped disks might not be sufficient on their own to produce back pain (some people with them don’t feel pain – if they were sufficient, everyone with them would feel pain). But they could still be partly responsible when combined with other factors, like muscle strain or posture. So the doctor’s reasoning is flawed because it treats “not sufficient” as “not causal at all.”
Hope that helps clarify! Let me know if you have further questions.
I interpreted C as, the lights work when there is no hurricane, so they might not work when there is a hurricane. Is my interpretation incorrect?
Edit: That interpretation isn’t quite correct–the answer choices each list examples of things people fail to consider when making arguments. So, the “Example of Flaw” in (C) is an example of the kind of reasoning that overlooks the possibility that an effect that occurs in the absence of a particular phenomenon might not occur when that phenomenon is present.
“The lights work when there is no hurricane, so clearly they’ll work when there is a hurricane.” This is flawed because it fails to consider that maybe the lights might not work when there is a hurricane.
If the example was written in the same way it is in your comment, then it wouldn’t be an example of the kind of flawed reasoning that overlooks the possibility described by (C).