PrepTest 137, Section 4, Question 14
Astronomer: Does a recent meteorite from Mars contain(78 more words not shown)
Which one of the following(12 more words not shown)
- AThe argument presumes,(15 more words not shown)
- BThe argument provides(20 more words not shown)
- CThe argument takes(20 more words not shown)
- DThe argument appeals(9 more words not shown)
- EThe argument presumes,(12 more words not shown)
Reading the argument
Why should we believe these two biologists rather than Tagar?
Tagar gives us a reason to doubt that the tiny structures are fossilized bacteria: they are much smaller than even the smallest bacteria on Earth. That comparison raises a question. Could Martian bacteria be different, or could something have made them shrink?
Swiderski and Terrada offer the shrinking explanation. They say shortages of water or other nutrients would reduce Martian bacteria to the tiny volume at issue. If that claim is right, the small size wouldn't rule out fossilized bacteria in the way Tagar thinks.
What we’re looking for
But what supports their claim? The astronomer rejects Tagar because Tagar doesn't accept those biologists' view, without explaining why their view deserves preference. We're allowed to consider their explanation without treating it as established. For the flaw question, that unsupported choice between competing experts is what I want to see.
Working the answers
- A
Nothing requires the experts to have held their views forever. They could have reached their current conclusions yesterday after years of study. The argument's problem concerns why one current view should be preferred, not how long anyone has held it.
- BCorrect
Tagar is a biologist, and so are Swiderski and Terrada. The astronomer accepts the latter pair's account while rejecting Tagar's, but supplies no evidence or reason for preferring their expertise on this issue. Pointing out that Tagar disagrees with them doesn't establish that Tagar is wrong.
- C
There are two biologists on one side and one on the other, but the astronomer never makes that numerical advantage the reason for accepting their view. If the argument said 'two experts outvote one, so they must be right,' C would fit. As written, the preference is unexplained rather than explicitly based on a head count.
- D
The competing views conflict, but the astronomer isn't relying on both as support. Tagar's position is presented in order to reject it; Swiderski and Terrada's position supplies the attempted rebuttal. Citing a view to dispute it isn't the same as accepting it as evidence.
- E
The astronomer does not treat all expert opinions as equally justified. The argument favors Swiderski and Terrada over Tagar. The problem is the lack of justification for that preference, not an assumption that every expert's opinion deserves equal acceptance.
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