Self-study
Support Not all tenured faculty are full professors. ██████████ ████████ █████ ███████ ██████ ██ ███ ███████████ ██████████ ███ ███████ ██ ████ ██ ███ ████ ████ ███ ███ ██ ███ ███████ ███████ ██ ███ ███████████ ██████████ ███ ████ ███████████
Method of Reasoning
The argument starts by stating that not all tenured faculty are full professors. It then uses that claim as a premise to state that while all the faculty in the linguistics department have tenure — another premise, embedded behind the "although" — it must be true that not all of these faculty are full professors.
Identify and Describe Flaw
This argument tells us that "not all" tenured faculty are full professors. This could mean that no tenured faculty are full professors, or it could mean that all the tenured faculty in the world, except one, are full professors. In short, this translates to "some" tenured faculty are not full professors: so we know that the set of "tenured faculty" and the set of "not full professors" intersect. We can write: tenure ←s→ /fullprof.
Then, we're told that all members of the linguistics department are tenured faculty. You could think of this as meaning that "faculty in the linguistics department" is a subset contained entirely within the set of "tenured faculty," or just translate this into a conditional. If a faculty member is in the linguistics department, then that faculty member has tenure: ling → tenure.
So far, we have:
Premise: ling → tenure ←s→ /fullprof
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Conclusion: ling ←s→ /fullprof
This conclusion (some faculty in the linguistics department must not be full professors) doesn't follow from the premises. Abstractly, just because all A are B, and some B are C, it doesn't follow that some A are C. This is the flaw pattern we're looking for:
Premise: A → B ←s→ C
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Conclusion: A ←s→ C
21.
The flawed pattern of reasoning █████████ ██ ███ ████████ █████ ██ ████ ███████ ██ ████ █████████ ██ █████ ███ ██ ███ ██████████
a
Although all modern ██████ ██████ ███ ██████████████████ ██████████ ███ ███ ██████ █████████ ███ ███████████████████ ██████████ ██ ████ ██ ███ ████ ████ ███ ███ ██████ █████████ ███ ██████ ██████ ███████
This answer choice isn't what we're looking for. It tells us that all modern office towers are climate-controlled: modern → CC. We're then told that not all office buildings are climate-controlled: thus, some office buildings are not climate-controlled (office buildings ←s→ /CC). We can link this "some" statement to the contrapositive of the "all" statement above: since office buildings ←s→ /CC, and if /CC → /modern, we can validly conclude that office buildings ←s→ /modern.
In short, the conclusion here is valid. This answer choice is tricky because it's hard to disqualify just based on language clues: as in the stimulus, we have an "all" statement with an "although," a conclusion with a "not all" introduced by "it must be the case," etc. We have to assess the underlying logic to disqualify this choice.
b
All municipal hospital █████████ ███ ████████ ███ ███ ███ █████████ ████████ █████████ ███ ██████████ ██ ███████████ ██████████ ███████ █████████ ████ ███ ███████ █ ██████████ ███████████
If all municipal hospital buildings are massive (MHB → massive), and at least some municipal hospital buildings are not forbidding (MHB ←s→ /forbidding), then it follows that at least some massive buildings aren't forbidding: /forbidding ←s→ MHB → massive, which lets us conclude /forbidding ←s→ massive. The reasoning here is valid, so this answer choice isn't what we're looking for.
c
Although some buildings ████████ ██ ██████ ██████████ ███ ███ ████ █████████████ ███ ██████████ █████████ ███ ████████ ██ ██████ ███████████ ██████████ ████ ██████████ █████████ ███ ███ ████ █████████████
This is what we're looking for. The argument starts with a "some" statement. Some buildings designed by famous architects aren't well-proportioned: famous arch ←s→ /well-prop. Then it tells us that all government buildings are designed by famous architects: govt → famous arch. It then tries to conclude that some government buildings must not be well-proportioned: govt ←s→ /well-prop.
The premises tell us: govt → famous arch ←s→ /well-prop. The conclusion says: govt ←s→ /well-prop. This is the same pattern as in our stimulus: A → B ←s→ C. Therefore — a flawed conclusion — A ←s→ C. Despite the change in subject matter, and the fact that the "some" statement is presented directly (and not as a "not all" statement), this logical structure matches our stimulus perfectly.
d
Not all public █████████ ███ ████ █████████ ███ ████ ██████ ████████ ██████ █████████ ████ ██████████ ████████ ███ ███████ ████ ██████████ ███ ██████ ████████ ██████ █████████ ████ ███ ██████████ ████████ ███ ███████ ████
Wrong flaw. This tells us that some public buildings are not well designed (public ←s→ /well-des), and then that some poorly designed public buildings were originally designed for private use: public AND /well-des ←s→ orig. private. (Note that this is being charitable to the argument. "Poorly designed" and "/well-designed" aren't necessarily equivalent). From these two "some" statements, the argument somehow derives an "all" conclusion: public AND /poorly designed → orig. private. This is a flawed argument, but a very different structure from what we're looking for.
e
Although some cathedrals ███ ███ █████ ██ ██████ █████ █████████ ██ ███████████ ██████████ █████████ ███ ██ ██████████ ████ ██████ ████ ███ ███ █████ ██ ██████
This tells us that some cathedrals are not made of stone (cath ←s→ /stone) and all cathedrals are impressive (cath → impressive). Linking this up, we get /stone ←s→ cath → impressive, and so we can infer that some buildings not made of stone can be impressive: /stone ←s→ impressive. Thus, the conclusion is valid. There is no flaw here, so this isn't what we're looking for.