PrepTest 111, Section 1, Question 24
In every case of political unrest in a(41 more words not shown)
The flawed reasoning in the(12 more words not shown)
- AEvery Chicago driver(28 more words not shown)
- BEvery telephone number(23 more words not shown)
- CEvery citizen of(23 more words not shown)
- DEvery loss of(20 more words not shown)
- EEvery moment in(17 more words not shown)
Reading the argument
Someone organized each incident. Why would that have to be the same person every time?
Imagine one protest organized by a group on the political right and another organized by an unrelated group on the left. Both incidents would have organizers. That wouldn't put one mastermind behind both. The police's finding is compatible with different people being responsible for different cases.
What we’re looking for
The conclusion combines those separate findings into a claim about one person who organized everything. That's the step I want the parallel answer to repeat: each case has someone or something associated with it, so one particular person or thing must be associated with every case. Keep an eye on the conclusion. “Everyone has one” is not the same as “everyone has the same one.”
Working the answers
- A
This makes a claim about an average: one driver's number must equal the average of all the numbers. An average needn't be one of the actual numbers, so the reasoning is questionable. But it doesn't conclude that all the drivers have one shared number. The original's mistake is shared identity, not the existence of an average value among individual cases.
- B
This makes a counting mistake. Many telephone numbers could share one area code, so assigning an area code to every number doesn't require at least as many area codes as numbers. B effectively rules out sharing; the original instead assumes one shared organizer behind everything.
- CCorrect
Each citizen corresponds to a case of unrest, and that citizen's social insurance number corresponds to the organizer of that case. Knowing each citizen has a number doesn't establish that one number belongs to all citizens. The numbers could differ, just as the organizers could differ.
The conclusion repeats the exact mistaken move: from a separate association in every case to one common thing across all cases. We don't need to know how social insurance numbers actually work to see why the premise doesn't establish that sameness.
- D
This moves from an insignificant individual loss to the claim that repeated losses cannot have a large result. Many small losses could add up. It doesn't infer one shared object or person from a series of individual associations, so its mistake differs from the mastermind argument.
- E
This reasons about an unending sequence of moments. It doesn't move from each moment having a successor to all moments having the same successor. Whatever questions we might ask about the premise or the endpoint of that sequence, E lacks the shared-identity claim that makes the original argument fail.
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