PrepTest 137, Section 2, Question 23
Three million dollars was recently stolen from the(43 more words not shown)
The flawed nature of the(17 more words not shown)
- Asome painters are(11 more words not shown)
- Bsome cabins are(11 more words not shown)
- Csome tables are(11 more words not shown)
- Dall supermarkets sell(11 more words not shown)
- Eall animals are(11 more words not shown)
Reading the argument
The mayor's staff and the suspects could be different former employees.
Imagine the City Treasurer's Office has 100 former employees. The suspects are people 1 through 5. Some people on the mayor's staff also used to work there, but they are people 90 through 100. Every suspect is a former employee, and the mayor's staff includes former employees. Yet none of those staff members is a suspect.
That's why sharing the larger category doesn't establish the overlap the conclusion claims. ‘All suspects are former employees’ doesn't mean every former employee is a suspect. Finding former employees on the mayor's staff therefore doesn't put suspects on that staff.
What we’re looking for
We need a parallel mistake. Keep the quantities and roles straight: all members of one group belong to a larger category; some members of a second group belong to that category; therefore, supposedly, some of the second group belong to the first. The two smaller groups could remain separate, just as our numbered employees did.
Working the answers
- A
Painters correspond to the mayor's staff, sculptors to suspects, and famous people to former employees. But A says some sculptors are famous; it does not say all are. Our argument says all suspects are former employees. A also makes an unsupported overlap claim, but its two ‘some’ premises don't match the original's ‘all’ premise plus ‘some’ premise.
- BCorrect
Cabins correspond to the mayor's staff, skyscrapers to suspects, and buildings to former employees. All skyscrapers are buildings, matching all suspects being former employees. Some buildings are cabins, which also means some cabins are buildings, matching some staff members being former employees.
Now comes the same unsupported overlap: some cabins must be skyscrapers. They needn't be. Cabins and skyscrapers can both belong to the building category without sharing any members. Reordering ‘some buildings are cabins’ doesn't change that overlap fact; if something is both, it can be described from either side.
- C
Tables and chairs both belong entirely to the furniture category. Our original puts all suspects in the larger category, but only says that some members of the mayor's staff belong there. C uses two ‘all’ premises rather than one ‘all’ and one ‘some.’ It makes a related overlap mistake, but doesn't preserve the exact pattern.
- D
This moves from supermarkets selling the broad category of food to every supermarket selling one particular food, asparagus. Our conclusion concerns some members of one group being members of another, not every seller carrying a particular item. Both the relationship and the quantity of the conclusion change.
- E
Animals correspond to one group, dogs to another, and pets to their shared category. But both premises give information about some members, and the conclusion suddenly concerns all animals. The original has one universal premise and concludes only that some staff members are suspects. E changes both parts of that structure.
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