LSAT 67, Logical Reasoning II, Q25, LSATHacks

LR Question 25 Explanation, by LSATHacks

QUESTION TEXT: Advertisement: The dental profession knows that brushing…

QUESTION TYPE: Flawed Parallel Reasoning

CONCLUSION: Dentists agree that brushing with Blizzard is the most effective way to fight cavities.

REASONING: Five out of five dentists agreed that the tartar control in Blizzard is the best tartar control available in a toothpaste.

ANALYSIS: Five dentists is much too small a sample to make a conclusion about the entire dental profession.

There are also flaws with the evidence. Maybe tartar control is useful, but not the most important thing in fighting cavities. It could be that other elements of toothbrushes are more important. Or maybe flossing is also more important.

___________

1. This does go from ten voters to all voters. But this argument goes from Gomez being popular to Gomez having the best policies. Those are unrelated: popularity doesn’t make policy. Tartar control is at least related to cavities.
2. This makes a conclusion about some voters. You can eliminate it instantly – the stimulus made a conclusion about the entire dental profession. Though the rest of this answer is nearly identical to the right answer.
3. Same as B. This says voters ‘generally’ believe. But we want a conclusion about all voters. Also, this argument sampled many voters, while the stimulus only sampled five dentists.
4. CORRECT. This repeats both major errors. It goes from a small sample to all of ‘the nation’s voters’. Secondly, it only considers one factor: Gomez’s policies. Good policies are helpful, but there are other factors that might not make Gomez best for the nation. Maybe he’s corrupt, or can’t work well with other politicians.
5. In the stimulus, we were told that the tartar formula is better than all others. Here, the voters just say that Gomez would ‘help’ the nation. That’s not the same as being more helpful than any other candidate.

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