Summary
All Harrison University Students live in either Pulham or Westerville.
A small fraction of the classes at Harrison are night classes.
38% of Harrison students take at least one night class.
29% of students living in Westerville take at least one night class.
Notable Valid Inferences
If a student doesn’t live in Westerville, the student lives in Pulham.
Over 38% of students living in Pulham take at least one night class.
A
More than 38 percent of the students at Harrison who live in Pulham take a night class.
Must be true. Since all students live in either Pulham or Westerville, the overall 38% night-class enrollment is an average of both groups. Westerville students have a lower rate (29%), meaning Pulham students must have a higher rate to balance the overall percentage at 38%.
B
More than 50 percent of the students who take night classes at Harrison are from Pulham.
Could be false. We don’t know how many students live in each dorm. It could be the case that Westerville has more students than Pulham––in this case, over 50% of the night class students would be from Westerville, even though only 29% of Westerville students take night classes.
C
More students at Harrison live in Westerville than live in Pulham.
Could be false. We don’t know anything about the relative sizes of the two residence complexes.
D
Harrison students living in Pulham are less likely than those living in Westerville to take more than one night class.
Could be false. We don’t know anything about people who take more than one night class. The stimulus only discusses students who take at least one night class.
E
Night classes at Harrison have larger enrollments, on average, than day classes do.
Could be false. We don’t know anything about the enrollment size of day classes.
Summarize Argument
The author concludes that a highly literate society will be a democratic one. This is based on the following facts:
Democracy requires free choices.
Free choices require well-reasononed opinions.
Well-reasoning opinions require reading skills.
Identify and Describe Flaw
The author confuses necessary conditions for sufficient conditions. Reading skills are necessary for well-reasoned opinions. But that doesn’t imply reading skills are enough for well-reasoned opinions. In addition, well-reasoned opinions are necessary for free choices, but that doesn’t imply they are sufficient for such choices. And free choices are necessary for democracy, but that doesn’t imply they are sufficient for democracy.
A
mistakes necessary conditions for sufficient conditions
The author confuses all of the necessary conditions described for sufficient conditions. This is why the author thinks a highly literate society (one with lots of reading skills) will be a democratic one.
B
fails to take into account that there are many means of forming well-reasoned opinions
Whether there are many ways to form well-reasoned opinion has no impact on the argument. We know reading skills are necessary for well-formed opinions. The author mistakenly believes having reading skills is sufficient for such opinions.
C
confuses the means of doing something with the reasons for doing it
The “reasons” for doing something — meaning, the motivations for doing something — are irrelevant. The flaw concerns a confusion of necessary and sufficient conditions. Why people take certain actions has no impact on the reasoning.
D
generalizes too hastily from one type of case to another
There’s no generalization. The author’s conclusion concerns the Information Age, and the premises also concern the Information Age.
E
takes for granted that a condition under which something occurs is a condition under which all its prerequisites occur
(E) doesn’t describe flawed logic. If X is a condition under which Y occurs, then X is also a condition under which prerequisites for Y occur (because prerequisites are necessary). In other words, if X implies Y, then it also implies everything necessary for Y.