PrepTest 141, Section 2, Question 5
Science writer: Lemaître argued that the universe began(58 more words not shown)
Which one of the following(10 more words not shown)
- AThe conclusion is(14 more words not shown)
- BThe conclusion is(19 more words not shown)
- CThe science writer(12 more words not shown)
- DThe science writer(22 more words not shown)
- EThe science writer(16 more words not shown)
Reading the argument
A theory makes a prediction, and the prediction comes true. That sounds promising, but does it prove the theory? Not necessarily. Something else might predict the same observation.
Then the writer goes too far in the other direction. Another theory does make the same prediction, so Lemaître's theory must be inadequate. Why would the second theory's success count as a failure for the first?
Could the two accounts even fit together? Imagine an expanding universe that later contracts and then expands again, like an accordion opening and closing. That is only a possible story to illustrate the question; the passage doesn't tell us what the oscillating theory says beyond its prediction. We haven't been given enough to declare the two theories incompatible.
What we’re looking for
The flaw question asks us to explain why the rejection doesn't follow. Having another possible explanation means we haven't uniquely proved Lemaître right. It doesn't mean we've shown him wrong.
Working the answers
- A
The writer describes Lemaître's view and then criticizes it. The conclusion isn't supported by “An expert says this theory is inadequate, so it is.” Questioning someone's theory is different from relying on that person's authority to establish your conclusion. Missing credentials don't describe the reasoning's problem.
- B
What word changes meaning? Think of “accident” meaning a dog making a mess indoors in one sentence and a car crash in another. An argument could go wrong by sliding between those meanings. Nothing similar happens here: the problem is what the writer infers from two theories making the same prediction.
- C
A theory about the universe's origin can involve causes, but that isn't enough to make this the flaw. The writer doesn't establish a causal connection between two observed events and then rely on that connection without support. The rejection rests on the existence of a second theory with the same successful prediction.
- DCorrect
A successful prediction by one theory isn't, by itself, evidence against another theory that predicts the same thing. Both fit this observation. Even if the theories ultimately conflict, we'd need additional evidence to choose between them. The shared prediction leaves the contest unresolved; it doesn't establish that Lemaître's theory is inadequate.
- E
The writer mentions two explanations without claiming they are the only possible ones. A third, fourth, or fifth theory could exist, and the same faulty rejection of Lemaître would still be present. The flaw concerns what the existence of an alternative is supposed to establish, not a claim that every other explanation has been ruled out.
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