LSAT 135 | Section 2 | Logical Reasoning: Q7

LR Question 7 Explanation

QUESTION TEXT: Gotera: Infants lack the motor ability required to …

QUESTION TYPE: Necessary Assumption

CONCLUSION: Speech acquisition is entirely a motor control process, not a mental process.

REASONING: Infants cannot voluntarily produce particular sounds, and children take several years to gain voluntary control over most speech sounds.

ANALYSIS: The evidence is all about producing speech sounds.

Babies babble randomly because they lack motor control. Children gradually gain control over their mouths and tongues. Eventually they can intentionally produce speech sounds.

But then Gotera concludes: speech acquisition is ENTIRELY a motor control process.

That’s a pretty big jump. The key word is entirely.

The argument assumes there isn’t anything else to speech acquisition besides learning to physically produce sounds.

What if speech acquisition also involves learning vocabulary, grammar, sentence structure, meaning?

Then motor control would only be part of speech acquisition, not the whole thing.

So the argument needs to assume that speech acquisition is nothing more than learning to produce speech sounds.

___________

1. CORRECT. This is the missing assumption. Suppose speech acquisition is not just about producing sounds, that it also involves abstract language learning. Then the evidence about motor control would no longer justify the conclusion that speech acquisition is entirely a motor process. The argument falls apart.
   Negation: Speech acquisition involves other factors besides just producing sounds.
2. Way too specific. The argument only needs the general idea that infants lack voluntary control over speech sounds. Whether they intentionally move their tongues during babbling doesn’t matter.
3. The timing of the babbling stage is irrelevant. Nothing depends on exactly when it ends.
4. Even if babbling weren’t the first stage, the argument could still make exactly the same inference.
5. This actually points in the opposite direction. If motor control itself requires substantial mental development, that would make the conclusion (that speech acquisition is not a mental process) less convincing. It’s certainly not an assumption the argument needs.