Necessary AssumptionDiff: Easy
Logic Breakdown
Passage Summary: Musicians have a specific part of their brain that's bigger than normal people's, so the researchers think playing music actually grows that part of the brain.
Conclusion: Engaging in musical training, especially early in life, is what leads to physical changes in the brain's structure.
Reasoning: There is a measurable correlation between being a musician—particularly one who started young—and having a larger corpus callosum compared to nonmusicians.
Analysis: The author assumes that the training causes the brain size difference, rather than the brain size difference causing people to become musicians. This is a classic causality gap where the author ignores the possibility of 'innate' traits. For this argument to hold, we must assume that people aren't simply born with larger corpora callosa which then makes them more likely to pursue music. Look for an answer that rules out this reversed causal relationship or ensures the brain wasn't already different before the training started.
Conclusion: Engaging in musical training, especially early in life, is what leads to physical changes in the brain's structure.
Reasoning: There is a measurable correlation between being a musician—particularly one who started young—and having a larger corpus callosum compared to nonmusicians.
Analysis: The author assumes that the training causes the brain size difference, rather than the brain size difference causing people to become musicians. This is a classic causality gap where the author ignores the possibility of 'innate' traits. For this argument to hold, we must assume that people aren't simply born with larger corpora callosa which then makes them more likely to pursue music. Look for an answer that rules out this reversed causal relationship or ensures the brain wasn't already different before the training started.
Passage Stimulus
Passage Redacted
Unlock Full Passage5.Which one of the following is an assumption on which the argument depends?
Correct Answer
A
A is necessary. If, before training, musicians already tended to have larger corpora callosa than nonmusicians, then the observed difference in adulthood could be due to preexisting anatomy rather than caused by training. Negation test: negate A to say, “Before training, musicians’ corpora callosa do tend to be larger.” That destroys the argument’s causal inference.
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