LSAT 135 | Section 2 | Logical Reasoning: Q9

LR Question 9 Explanation

QUESTION TEXT: Reducing stress lessens a person’s sensitivity to pain …

QUESTION TYPE: Necessary Assumption

CONCLUSION: Reducing stress makes people less sensitive to pain.

REASONING: Patients who listened to music before and after surgery needed less anesthesia during surgery and fewer painkillers afterward than patients who listened to conversation.

ANALYSIS: This is what they observed:

• Group 1 listened to music.
• Group 2 listened to conversation.
• The music group needed less anesthesia and fewer painkillers.

From that, they conclude: reducing stress makes you less sensitive to pain.

But wait? Where did stress come from? They didn’t actually measure stress. They only measured what people listened to and how much anesthesia/pain medication they needed.

So how do the researchers get from “music” to “reduced stress”?

They have to assume that listening to music reduces stress.

Without that assumption, the results could have some completely different explanation. Maybe music directly affects pain perception, or maybe it changes brain chemistry in some other way. If music doesn’t reduce stress, then the study provides no evidence that stress is what caused the lower pain sensitivity.

___________

1. This strengthens the experimental design, but it’s not required. Even if some patients switched tapes, the argument could still work as long as the groups differed overall.
   Negation: At least one of the patients switched the tape they listened to before and after the surgery.
2. The relative stress of the two time periods isn’t important. The conclusion is about whether reducing stress reduces pain, not whether one stage is more stressful than another.
   Negation: Anticipating surgery is less stressful than recovery.
3. CORRECT. This is the gap. The researchers conclude that stress reduction caused the lower need for anesthesia and painkillers, but the only difference between the groups was music versus conversation. So they must assume music actually reduced stress.
   Negation: Listening to music does not reduce stress.
   (If the negation were true, then the study no longer tells us anything about whether reducing stress affects pain. The conclusion falls apart.)
4. The argument doesn’t depend on this. The researchers are comparing medication use, not studying whether medication changes how music affects people.
   Negation: The psychological effects of music are changed by medicine.
5. This reverses the causal direction. The conclusion is that stress reduction leads to less pain, not that pain medication reduces stress. Whether anesthesia lowers stress is irrelevant to the reasoning.
   Negation: It is not the case that both anesthesia and painkillers tend to reduce stress.