Self-study
Support Research indicates that 90 percent of extreme insomniacs consume large amounts of coffee. █████ ███ ██████ █ ███ ██ ███████ ██ ██ █████ ██████ ████ ██ ██ ██ ███████ ██████████
Summarize Argument
The author concludes that it’s likely Tom is an extreme insomniac. This is based on the fact that 90 percent of extreme insomniacs drink lots of coffee, and Tom drinks lots of coffee.
Identify and Describe Flaw
The author misinterprets the claim “Most A are B” as “Most B are A.” Although 90 percent of extreme insomniacs drink lots of coffee, that doesn’t tell us anything about what proportion of lots-of-coffee drinkers are extreme insomniacs. It could be that the vast majority of lots-of-coffee drinkers aren’t extreme insomniacs, even if most extreme insomniacs drink lots of coffee.
23.
Which one of the following ████ ██████████ █████████ █ ████ ██ ███ ██████████ ██████████
a
It fails to ███████████ ███ ███████████ ████ ███ ██ █████ ███ ██ ███████ ██ ██████ ███ █████ █████ ███████ ██ ██████ ███ ███ ███ ███████ ███████████
The premises don’t establish that only 10 percent of people who drink lots of coffee are not extreme insomniacs. Also, the conclusion doesn’t say that Tom definitely is an extreme insomniac. So, the author acknowledges that he might not be an extreme insomniac.
b
It fails to ████████ ███ ████████ ████████████ ██ ███████ ████████ ██ █████ ██████ ██ ████████ ███████ ███████
The author’s argument does not make any assumptions about cause. The issue is whether membership in the set of people who drink lots of coffee implies a likelihood of membership in the set of people who are extreme insomniacs.
c
It relies on ████████ ████ ████ ███ ████████ ███ █████████ ██ ███████ ████████ █████ ██████ ███ █████ █████ ███████ ██ ███████
The author relies on the fact that 90% of extreme insomniacs drink lots of coffee. This does not reveal the frequency (i.e. proportion) of extreme insomnia among people who drink lots of coffee. It could be that only a small % of lots-of-coffee drinkers have extreme insomnia.
d
It draws an █████████ █████ ███ ████████ ██████████ ████ ████████ ████ █████████ ████ ███ ███████████████ ██ █ █████ ██ ████████████
The author does not commit the whole-to-part fallacy. The issue is misinterpretation of the claim “90% of extreme insomniacs consume lots of coffee.” This statistic is not a claim about a class — it’s a claim about 90% of the individuals within the class.
e
It presumes without ███████ ████ ████████ ██████ ██████ ██████ █████████
The author doesn’t make any assumptions about cause. The issue is whether membership in the set of people who drink lots of coffee implies a likelihood of membership in the set of people who are extreme insomniacs.