Self-study
Sam: In a recent survey, over 95 percent of people who purchased a Starlight automobile last year said they were highly satisfied with their purchase. █████ ██████ ███ ████ █████████ █ ███ ███ ██ ███ ████ ████ ███ ███ ██████ █████████ ██ ████ ███ ███ █ █████████████ ███████ █████████ ███████████ ███ ██████████ ████ ████ ████ ████████
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Summarize Argument
Sam mentions a survey showing that 95 percent of people who purchased a Starlight automobile in the last year said they were highly satisfied with it. Based on the premise that if the cars had manufacturing defects, these people would not have been highly satisfied with the cars, Sam concludes that Starlight automobiles must be "remarkably free" of manufacturing defects. Tina just responds by saying that some manufacturing defects in cars don't become evident until after several years of use, implying that Starlight automobiles aren't necessarily free of manufacturing defects — the manufacturing defects might just not have become clear to the owners, who have had the cars for less than a year.
Describe Method of Reasoning
Sam's argument has a few flaws. Notice, for example, that to say Starlight automobiles are "remarkably free" of manufacturing defects makes an implicit comparison to other automobiles, and assumes that other brands will have more defects.
Tiya's argument, meanwhile, is focused on Sam's assumption that the survey evidence is sufficient for drawing a conclusion about manufacturing defects. By pointing out that some manufacturing defects don't show up until years later, Tiya calls into question whether Sam's evidence is sufficient to come to his conclusion, since his evidence is a survey entirely focused on Starlight automobile owners within a year from their purchase. Thus, Tiya suggests that the timeframe of the survey is too short to use the survey evidence to come to a conclusion about manufacturing defects.
This, in turn, undermines Sam's conditional premise that if the cars had manufacturing defects, the survey respondents would not have been highly satisfied with the cars. The new information reduces this claim, at best, to "if these cars had manufacturing defects that showed up in the first year, these people would not have been highly satisfied with these cars". Since Sam's argument relies so heavily on the contrapositive of the original premise — since these people were satisfied with the cars, the cars must be free of manufacturing defects — the additional information Tiya provides thus strongly undermines all the support, meaning both the evidence and the conditional premise, for Sam's conclusion.
7.
Which one of the following ████ ██████████ █████████ ███ ██████ ████████ ██ ███████ ██ █████ █████████
a
It argues that █████ ██████████ ██ ████████ ██████ ███ ███ ███ ███████ ███ ██████
Tiya never says Sam's conclusion is correct. Her argument actually doesn't force a verdict on Sam's conclusion either way — we can't tell if Tiya thinks Starlight automobiles are unusually free from manufacturing defects or not — but only presents additional information whose effect is to weaken the support for Sam's conclusion.
What this answer choice gets right is that if Tiya did agree with Sam about Starlight automobiles being free of defects — and we don't know if she does — she would certainly think Sam believed this for the wrong reasons, since her whole argument here is meant to show the problems with the support Sam provides.
b
It provides evidence ██████████ ████ ███ ██████ ███████ ███ ██████ ██ ██ ███ ████████ ██ ███ ██████████ ████████████ ███ █████████ ██ █████ █████████
While Tiya's argument does suggest a limitation of Sam's survey evidence — the survey looks only at people who purchased a Starlight automobile in the last year, while manufacturing defects can take longer than a year to become apparent — Tiya never says the survey doesn't accurately reflect whether the purchasers are actually satisfied with the cars or not.
c
It offers a █████████████ ████ ██████████ ███ ███████ ███ ██████ ███ ███ ███████████
This is correct. By pointing out that some manufacturing defects are apparent only after several years, Tiya points out a significant flaw in Sam's evidence and reasoning, since he reaches his conclusion about Starlight automobiles lacking manufacturing defects based only on evidence from people who have owned Starlight automobiles for less than a year.
d
It points out ████ █████ ████████ ███████████ ███ █████ ██ ███ ██████████ ███ ██ ██████████
Tiya does not claim Sam's argument is circular, which is what this answer choice means.
e
It presents new ███████████ ████ ███████ ████ █████ ██████████ ██ ██████
This is tempting, because the information Tiya provides weakens Sam's argument. But while this information weakens the support Sam provides for his conclusion, it doesn't actually imply anything about the truth or falsehood of the conclusion itself. It could still be the case that Starlight automobiles are actually unusually free of manufacturing defects, and no defects will show up even a few years down the line. We don't know what Tiya actually thinks about this conclusion, but we do know that she thinks Sam has reached his conclusion based on evidence that is too limited.