PrepTest 148, Section 1, Question 24
Lucinda will soon be attending National University as(22 more words not shown)
Which one of the following(16 more words not shown)
- AA major shopping(28 more words not shown)
- BCities that are(36 more words not shown)
- CCities that are(30 more words not shown)
- DA major shopping(36 more words not shown)
- EMost cities that(29 more words not shown)
Reading the argument
What about the other dorms? Western Hall could be full of engineering majors without being where most engineering majors live. Maybe this is a university with 20 dorms and engineering majors in every one of them. Learning Lucinda's major would still leave us with 20 possible places for her to live.
Try the same reasoning somewhere else: suppose most people who live in Ghana drink coffee. Ben drinks coffee, so Ben probably lives in Ghana. That doesn't follow. Plenty of people outside Ghana could drink coffee too. Likewise, plenty of engineering majors could live outside Western Hall.
What we’re looking for
For the parallel flaw, we want the argument to say that most members of a group have a trait, then use someone's having that trait to place them in the group. Keep the direction straight. Information about Western Hall residents doesn't automatically tell us where an engineering major probably lives.
Working the answers
- A
This goes in the stated direction. Most cities with malls are economic hubs; our city is getting a mall; therefore, it will probably be a hub. In the original terms, that would be like saying most Western Hall residents are engineering majors, Lucinda will live in Western Hall, so she'll probably be an engineering major. The original instead starts with her major and guesses her residence. A doesn't make that reversal.
- B
This applies a general pattern about economic hubs to a city already identified as an economic hub, then reasons about when its growth will occur. Its issue concerns moving from growth at some point to growth in the future given none in the past. It doesn't take a feature common within one group and use that feature to assign the city to the group. We don't need to settle the strength of its timing prediction to see the different structure.
- C
This treats a present problem as though it will prevent something forever. Even if an economic hub needs excellent transportation, the city might improve its currently inadequate system and later become a hub. That's different from mistaking a common feature of group members for evidence of membership. In Lucinda's argument, nobody predicts that a present condition can never change.
- D
This starts with one city's experience and generalizes to most cities. A mall was built, growth followed, and the argument predicts that pattern elsewhere. The original starts with a statement about most members of a group and tries to locate one person within it. The direction and the comparison are different.
- ECorrect
Economic hubs correspond to Western Hall residents. Having a major mall corresponds to being an engineering major. Our city corresponds to Lucinda. Most hubs have malls, and our city is getting a mall, so the argument concludes it will probably be a hub.
But many cities that aren't hubs might also have malls, just as many engineering majors might live outside Western Hall. In both arguments, the common trait within the group is treated as enough to make the particular case a probable member. That is exactly the mistake we wanted.
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