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Parallel Reasoning, SN. The correct answer choice is (C)
The above-average difficulty level of this question is primarily due to the confusing approach taken
in creating the five answer choices, rather than the stimulus itself. The stimulus contains an argument
with a relatively simple structure, as described below. The answer choices, however, test your ability
to compare and contrast the abstract relationships that underlie each argument. It does not help
that all five of them deal with the same topic, which—though irrelevant to the structure of each
argument—makes your task even more challenging.
It may be helpful to diagram the argument contained in the stimulus as if it contained conditional
reasoning. However, keep in mind that the relationships in each premise are less than absolute, due
to the use of such phrases as “typically” and “tend to.” Nevertheless, since our primary objective is to
understand the logical structure of the argument as clearly as possible, such a conditional approach
would be justified, albeit with a caveat.
The first sentence indicates that cities with healthy economies typically have plenty of job openings:
- HE = Healthy economies
JOB = Job openings
HE tend JOB
have healthy economies:
- Hi-Tech = Cities with high-technology businesses
Hi-Tech t end HE
- High-Tech tend HE tend JOB
a city with high-technology businesses. In other words, those in search of the necessary condition
should seek an area where the sufficient condition occurs. Note that this is not a Mistaken Reversal;
the author does not suggest that the necessary makes the sufficient condition occur, but rather that
looking for the sufficient condition is a viable approach if you want find the necessary condition.
Our job is to parallel the reasoning contained in the stimulus. To do that, we must parallel the
conclusion as well as the premises, making sure to “match” the language of both. First, we need to
find an answer choice in which the conclusion that uses the language of a recommendation (words
such as “should,” “must,” “ought to,” etc.) and suggests that seeking a sufficient condition is an
advisable avenue if one seeks the occurrence of the necessary condition. On the premise side, the
correct answer choice will contain the two premises that can be combined, and whose wording
makes make the conditional relationship between them less than absolute.
Because the argument is not flawed, the question stem does not indicate the presence of a logical
Answer choice (A): This answer choice can be diagrammed as follows:
- Premise (1): Older antiques Usually most valuable antiques
Premise (2): Antique dealers Authenticate age
Conclusion: Buy most valuable antiques Antique dealers
choice. Indeed, just because antique dealers authenticate the age of the antiques they sell, that does
not necessarily mean that they sell older antiques. Since the conclusion does not follow from the
premises, this answer choice is incorrect.
Answer choice (B): This answer choice, when re-worded, has the following argument structure:
- Premise (1): The most valuable antiques are those whose age has been authenticated.
Premise (2): Dealers who authenticate the age of the antiques they sell have plenty of
antiques for sale.
Conclusion: Buyers of valuable antiques should purchase them from antique dealers.
“plenty” of antiques for sale does not automatically make them the most valuable. Do not get
distracted by the repetition of the word “plenty,” which also appears in the stimulus—this similarity
is irrelevant to the logical structure of the argument. Lastly, just because an antique collector is
searching for valuable antiques, that does not mean she is in search for the most valuable antiques.
Since either of these inconsistencies would be sufficient to eliminate this answer choice from
consideration, no conditional diagramming is necessary to prove it wrong.
Answer choice (C): This is the correct answer choice. The argument has the following structure:
- Premise (1): Age authenticated tend Valuable antiques
Premise (2): Antique dealers generally Age authenticated
Conclusion: Valuable antiques Antique dealers
- Antique dealers generally Age authenticated tend Valuable antiques
their antiques from antique dealers. Since antique dealers do sell valuable antiques, the author’s
conclusion is reasonable.
Some students object that the wording in this answer choice is not identical to that in the stimulus.
But, “generally” and “tend” have the same logical force, and thus there is no problem with the
wording; synonymous words and phrases are acceptable because you attempting to parallel the
structure, not the exact wording.
Answer choice (D): This answer choice fails to Double the Conclusion and can easily be ruled out.
The conclusion in this answer choice does not contain a recommendation (“should”), but rather a
statement of fact (“most antique collectors who want antiques that are valuable tend to purchase their
antiques from antique dealers”), which is sufficiently different to make this answer incorrect.
Answer choice (E): Hopefully, you were able to eliminate this answer choice rather quickly. The first
premise indicates that many antiques increase in value once they have had their ages authenticated
by antique dealers; however, this information is irrelevant to the remainder of the argument and
cannot be combined with the second premise. Because the second premise provides independent
grounds for the conclusion of the argument, the pattern of reasoning contained in this answer choice
deviates significantly from that in the stimulus.