Self-study
Support Linda says that, as a scientist, she knows that no scientist appreciates poetry. ████ █████ ████ ██████████ ███ ████████ ██ █████ ████ ██ ███ ██████ ███ ██████████ ██████ ███ ██████████
Method of Reasoning
The argument starts with a claim by Linda, who appeals to her experience as a scientist to state that no scientist appreciates poetry. The argument then builds on Linda's claim, adding another premise: most scientists are logical. From these two premises, the argument concludes that at least some people who appreciate poetry are illogical.
Identify and Describe Flaw
Besides the flaw of assuming without warrant that Linda's assertion is actually true, just because she is a scientist, the argument is flawed because it incorrectly combines the two premises. Linda's claim that no scientist appreciates poetry translates to "all scientists do not appreciate poetry." The next statement, "most scientists are logical," also implies "some logical people are scientists." Combining these two statements, we can conclude that some logical people do not appreciate poetry: logical ←s→ /appreciate. But the conclusion of this argument incorrectly tries to take a "contrapositive" of this "some" statement, to claim that some people who appreciate poetry are illogical: appreciate ←s→ /logical.
Expressing this graphically, we have:
(Linda says) scientist → /appreciate
scientist -m→ logical
______
appreciate ←s→ /logical. (Somehow, the negation moves from "appreciate" to "logical").
More abstractly, we're looking for an answer choice following this pattern:
(someone's assertion) A → /B
A -m→ C
______
B ←s→ /C
23.
Which one of the following ██ ████ ████████ ██ ███ █████████ ██ ███ ██████ █████████ ██████
a
Ralph says that, ██ ██ ██████ ██ ████████ ██ █████ ████ ██ █████████ ████ █████ ████ █████ ████ ██████████ ███ ██████ ██ ██████████ ██ █████ ████ ██ ███ ███████ ██████ ██ █████████ ██ ███ ███ █████
There isn't a flaw in the conditional logic here. If all marsupials do not lay eggs, and at least some marsupials are native to Australia, then it follows that some animals native to Australia do not lay eggs:
mars → /eggs (A → /B)
mars ←s→ Australia (A -m→ C)
______
Australia ←s→ /eggs. (C ←s→ /B)
This is a valid conclusion taking the form C ←s→ /B. We're looking for an invalid conclusion that says B ←s→ /C.
b
Franz says that, ██ █ ██████ ██ ████ █████████ ██ █████ ████ ██ ██████ █████ ████████ ██ ███ █████ ██ ████████ ████ █████ ████ ███████ ███ ███████ ██ █████ ████ ██ ███ ██████ ███ ████ ████████ ██ ███ █████ ██ ███████ ███ █████████
This parallels our stimulus:
(Franz says) father → /want children eat candy (A → /B)
father -m→ adult (A -m→ C)
______
want children eat candy ←s→ /adults (B ←s→ /C)
The legitimate conclusion would be "some adults do not want their children to eat candy at bedtime" (adult ←s→ /want children eat candy). This answer choice instead concludes a "contrapositive" of that statement: some people who want children to eat candy at bedtime are children (/adults). This is the same pattern as in the stimulus.
c
Yuri says that, ██ █ ████ ████████████ ██ █████ ████ ██ ████ ████ ██ █████ ██████████ ██ █████ ██ ███████ ██ ███ ████ ████ ████ ██ ████ ████ █████ ████ ██████████ ████ ██ ████ ██ █████ ███████████ ██████████ ████ ██ ████████ ██ ██ █████ ███ ████ ██████ ████ ████ ██ ████
This is a different flaw than what we're looking for. It runs:
(Yuri says) metal → /equal to best oak (A → /B)
California -m→ metal (C -m→ A)
______
California → /equal to best French oak (C → /D)
Notice the flaws here. From Yuri's premises, we could reach the conclusion that most California wine is not equal to the best wine aged in oak (California -m→ /equal to best oak). But instead Yuri reaches a conclusion about all California wine, somehow comparing it to the best French wine aged in oak. We know nothing about how good French wine is, compared to the best wine aged in oak in general. This is flawed, but a different pattern than we're looking for.
d
Xi says that, ██ ██ ███████████ █████████████ ███ █████ ████ ██ █████ ████ ████████ ██████ ██ █████ ██ ███ ████ ███████████████ █████ ████ █████ ████ ███████ ████ ██ █████ █████ ██ █████ ████ ███████ ████ ████████ ██████ ████ █████ ████ ███ ████ ███████████████ █████
No flaw in the conditional logic. If all color film produces images less sharp than the best black-and-white film, and most instant film is in color, then it follows that at least some (in fact, most) instant film must produce images less sharp than the best black-and-white film.
(Xi says) color → /as sharp than bw (A → /B)
instant -m→ color (C -m→ A)
______
instant -m→ /as sharp than bw (C -m→ /B)
This is a valid argument.
e
Betty says that, ██ █ █████████ ██████████ ███ █████ ████ ██ █████████ ██████████ ████ ██ ███ ██████ ████ █████ ████ █████████ ██████████ ███ ██████ ███████ ██ █████ ████ ██████ ███ ████ ██ ███ █████ ███ ██████ ███████
Wrong flaw. Notice how the argument runs:
(Betty says) corp → /like pay taxes (A → /B)
corp -m→ honest (A -m→ C)
______
like to pay taxes ←s→ honest (B ←s→ C)
From Betty's premises, we could legitimately conclude that some honest people do not like to pay taxes (C ←s→ /B: honest ←s→ /like to pay taxes). A flawed conclusion following the same lines as the stimulus would be that some people who like to pay taxes are not honest (B ←s→ /C: like pay taxes ←s→ /honest). But this answer choice somehow reaches a conclusion about people who both like to pay taxes and are honest, which is not supported, but a different flaw from what we're looking for.