LSAT 144 | Section 1 | Reading Comprehension: Q21

RC Question 21 Explanation

QUESTION TEXT: Which one of the following is mentioned in…

DISCUSSION: Passage A talks about how negative evidence can disprove a theory. Passage B actually gives an example of a theory being disproved.

Those are the main points of each passage, so I assumed they might be the answer. And they were. It’s useful to predict the answer in advance, even if you may only be 70% sure it will be right. If it is right, you go much faster. If it isn’t, you’ve lost very little, as prephrasing forces you to think everything over regardless.

___________

1. Neither passage mentions this. In fact passage B doesn’t even mention experiments.
2. Neither passage mentions revising a theory. Discarding an auxiliary assumption is not “revising a theory”. Auxiliary assumptions are separate from theories, see lines 22-28 for discussion. The author says it’s not clear “which one” is false, implying that negative evidence could disprove auxiliary assumptions while leaving a theory unaffected.
    
   Example of revising a theory: Previously, we thought all butterflies are orange or blue. But now we think they can be orange or blue or green. However, the old theory is still broadly correct, as 99% of butterflies are orange or blue.
3. CORRECT. See line 20 and line 62.
4. Passage A doesn’t mention planets.
5. Passage B doesn’t mention experiments. Passage A mentions testable theories in lines 15-16, but it doesn’t specify if the tests must be by experiment.