LSAT 144 | Section 1 | Reading Comprehension: Q24

RC Question 24 Explanation

QUESTION TEXT: The author of passage A would be most likely to…

DISCUSSION: The last sentence of passage A says “negative evidence rarely is [conclusive]”. So we need a statement that shows that initial negative evidence wasn’t determinative.

Newton’s laws failed to predict Uranus’ orbit. But eventually the theory was kept, because the discovery of Neptune showed that it was an auxiliary assumption, and not the theory, that was wrong.

Also, this is a basic point, but if you look at the answers before you’ve reread the last sentence of passage A, you’ve committed a grievous error. The answers are designed to scramble your brain – on this type of question you should figure out the answer before you look at the answer choices.

___________

1. We have no idea if any theory predicted Uranus’ existence before it was discovered.
2. CORRECT. This failure was negative evidence, but ultimately it didn’t lead to the rejection of Newton’s theory. So this supports the idea that negative evidence isn’t conclusive.
    
   You might have avoided picking this because Newton’s theory was eventually rejected. But that doesn’t matter. At the time, Newton’s theory seemed good, and scientists were correct that the initial failure to predict Uranus’ orbit was not actually evidence against Newton’s theory.
3. In the case of Mercury, the negative evidence did lead to the rejection of Newton’s theory.
4. This is the same as C. The failure to find Vulcan showed that Newton’s theory itself might be wrong, and was negative evidence against it.
5. This is an example of an observation confirming a theory. It’s positive evidence, not negative evidence.