PrepTest 144, Section 1, Question 24
Passage A Karl Popper's main contribution to the(496 more words not shown)
Passage A(258 more words not shown)
Passage B(246 more words not shown)
The author of passage A(29 more words not shown)
- Athe discovery of(1 more words not shown)
- Bthe initial failure(8 more words not shown)
- Cthe ultimate failure(8 more words not shown)
- Dthe failure to(2 more words not shown)
- Ethe success of(9 more words not shown)
Reading the passage
A ends by saying that negative evidence is rarely conclusive. We want a case where a failed prediction initially looks bad for a theory, but does not settle that the theory is false.
What we’re looking for
Uranus gives us exactly that pattern. The initial Newton-based prediction fails, yet finding Neptune fixes the missing-planet assumption and brings the calculation into agreement with observation. The problem was not necessarily Newton's laws.
Working the answers
- A
Discovering Uranus provides an object whose orbit can be studied. That discovery alone is not a failed prediction, so it does not illustrate the limit on negative evidence.
- BCorrect
The initial failure could have been blamed on Newton's laws, but the later discovery of Neptune explains it through an incorrect auxiliary assumption. The failed prediction therefore did not conclusively disprove the theory. That is the uncertainty A's final sentence describes.
- C
The ultimate Mercury failure contributes to rejecting Newton's theory. That is different from the Uranus case, where the initial failure is resolved while retaining Newton's laws. We need the latter to show why negative evidence need not settle the theory's fate.
- D
Failure to find Vulcan does not supply the clear resolution that makes the Uranus example useful. It contributes to doubt about the proposed explanation of Mercury's orbit; B does not show a later discovery that resolves this failure while preserving Newton's theory.
- E
Einstein's successful Mercury prediction is positive evidence supporting Einstein's theory. It is not the example of negative evidence failing to disprove the theory under examination.
More Application questions
Learn the LSAT our way
Our platform drills Application questions at your level and adjusts as you improve.