Summarize Argument
The medical reporter claims that most people in industrialized nations would benefit from taking an aspirin a day. This is because aspirin helps with heart disease, which is common in these nations.
Identify and Describe Flaw
The flaw here amounts to missing the key difference between what’s common and what’s true of most people. Heart disease may be one of the most common illnesses, but that doesn’t mean that the majority of people suffer from it. Since the conclusion is that aspirin will benefit most people in the nation, merely establishing that the illness it treats is common is not enough to justify it.
A
It takes for granted that if medication can reduce the severity of heart disease, it can also prevent some cases of heart disease.
The argument doesn’t claim that aspirin prevents heart disease, just that it improves health. The flaw lies in the presumption that this applies to most people in these nations.
B
It overlooks the possibility that even if a disease is one of the most common in a nation, most people in that nation are not in significant danger of developing that disease.
This describes how the argument fails to justify the claim that aspirin would benefit the majority of people. Simply establishing that the disease it treats is common isn’t enough.
C
It overlooks the possibility that preventing or reducing the severity of heart disease has little or no effect on any of the other most common diseases in industrialized nations.
This is irrelevant. The doctor’s claim is that aspirin helps with heart disease, thereby improving health. It doesn’t matter whether or not it affects other diseases. The flaw is assuming that aspirin would improve health for the majority of people in these countries.
D
It fails to address the possibility that taking an aspirin a day is not the single most effective measure for preventing heart disease.
This is irrelevant because the doctor never claims that it’s the best at preventing the illness, only that it helps. The flaw is assuming that this would be helpful for most people in these countries.
E
It fails to address the possibility that the studies on the beneficial effects of aspirin were conducted only in industrialized nations.
This is irrelevant. There’s no reason to believe that conducting studies in industrialized nations would make their findings less reliable.
Essayist: Winners of a Nobel prize for science, who are typically professional scientists, have all made significant contributions to science. But amateur scientists have also provided many significant contributions. And unlike professional scientists, who are often motivated by economic necessity or a desire for fame, amateur scientists are motivated by the love of discovery alone.
Summary
The stimulus can be diagrammed as follows:
Notable Valid Inferences
Some scientists who have provided significant contributions are motivated by the love of discovery alone.
Some professional scientists have provided significant contributions to science.
A
Some amateur scientists who did not win a Nobel prize for science nevertheless made significant contributions to science.
This could be false. We don’t know anything about the group of amateur scientists who have not won a Nobel prize for science.
B
Typically, winners of a Nobel prize for science are not motivated at all by the love of discovery.
This could be false. All we know about winners of a Nobel prize is that most of them are professional scientists and all of them have made significant contributions to science. We can’t make inferences about their motivations.
C
The love of discovery is the motive behind many significant contributions to science.
This must be true. As shown below, there is some overlap between the group of scientists who have made significant contributions and those who are motivated by the love of discovery. “Many” translates to “some.”
D
Professional scientists have made a greater overall contribution to science than have amateur scientists.
This could be false. We don’t have the information to compare the extent of overall contributions to science between professional and amateur scientists.
E
A professional scientist is more likely to make a significant contribution to science if he or she is motivated by the love of discovery.
This could be false. We don’t have any information that indicates how likely one is to make significant contributions to science depending on their motivations.
Summarize Argument: Phenomenon-Hypothesis
The author concludes that, when hiring sales reps, we should favor applicants who have engineering degrees but little/no sales experience over applicants with lots of sales experiences but no engineering degrees. This is based on the fact that most of the company’s best sales representatives had an engineering degree but little/no sales experience when joining the company.
Notable Assumptions
The author assumes that the explanation for why most of the best sales representatives have an engineering degree and little/no sales experience is that this background contributes to success. But this overlooks the possibility that there are other explanations. For example, what if most people hired for a position as a sales representative have the background described? Then we’d expect most of the best reps to have that background.
A
Some of the company’s sales representatives completed a degree in engineering while working for the company.
The argument is just about what kind of background we want at the time of hiring. Whether reps who started without an engineering degree later got a degree doesn’t alter the support provided by the fact that most of the best reps started without an engineering degree.
B
Most of the people hired by the company as sales representatives have had a degree in engineering but no sales experience.
This provides an alternate explanation for the statistic about the best reps. Maybe the reason most of the best have that background is that most sales reps have that background. So, we’d expect most of the best to have that background even if it doesn’t contribute to success.
C
Most of the customers that the company’s sales representatives work with have a degree in engineering.
The background of customers is irrelevant. The argument is based on the background of the best sales reps.
D
Most of the people who apply for a sales representative position with the company do not have a degree in engineering.
If anything, this strengthens the argument by eliminating the potential alternate explanation that most applicants for a sales rep position have an engineering degree and little/no sales experience.
E
Some of the people who the company has hired as sales representatives and who were subsequently not very good at the job did not have extensive previous sales experience.
The author already acknowledges that “most” of the best have a particular background. This doesn’t mean the author thinks all of the best have that background.
Summarize Argument: Counter-Position
The anthropologist concludes that taboos against eating certain animals may not have arisen for practical reasons, like the value of animal labor. This challenges some researchers’ view that the taboos must have had a practical basis. His reasoning is that it’s possible the taboos against eating animals arose first, and people only realized afterwards that they could use the animals for labor.
Describe Method of Reasoning
The anthropologist challenges some researchers’ hypothesis by offering an alternative that accounts for the same facts. He doesn’t claim their hypothesis is false, only that it isn’t necessarily true.
A
calls an explanation of a phenomenon into question by pointing out that observations cited as evidence supporting it are also compatible with an alternative explanation of the phenomenon
The phenomenon is taboos against eating animals, and the explanation is the practical value of animals, e.g. for labor. The anthropologist calls it into question by suggesting that the taboos could have arisen first, and then were followed by the practical usage of animals.
B
establishes that an explanation of a phenomenon is false by demonstrating that the evidence that had been cited in support of that explanation was inadequate
The anthropologist doesn’t argue that the explanation is false, only that it could be false.
C
rejects the reasoning used to justify a hypothesis about the origins of a phenomenon, on the grounds that there exists another, more plausible hypothesis about the origins of that phenomenon
The anthropologist doesn’t say that the other hypothesis is more plausible, only that it’s also plausible.
D
argues in support of one explanation of a phenomenon by citing evidence incompatible with a rival explanation
The anthropologist argues that the evidence could support an alternative explanation, not that it’s incompatible with the original explanation. His argument is that two different hypotheses are consistent with the same set of facts.
E
describes a hypothesis about the sequence of events involved in the origins of a phenomenon, and then argues that those events occurred in a different sequence
The anthropologist doesn’t argue that the events did occur in a different sequence, only that they could have occurred in a different sequence. Like (C) and (B), this is overstating the anthropologist’s belief.
Summarize Argument
The author argues that there’s reason to believe that the government’s plan to reduce underage drinking by having adolescents take a pledge has been successful. This is because a survey of teenagers found that a number of non-drinkers took the pledge, whereas most drinkers didn’t.
Identify and Describe Flaw
This is a correlation-causation fallacy. The argument takes a weak correlation (the fact that some non-drinkers have taken the pledge) and attempts to use it as evidence that the pledge causes people to not drink. This is particularly weak because it’s likely tainted by selection bias, since people who already abstain from drinking would probably be more likely to take the pledge. Moreover, we don’t even know how strong the correlation is because “many who do not drink” is too vague to determine the pledge’s success rate.
A
bases a conclusion about the efficacy of a method to reduce underage drinking merely on a normative judgment about the morality of underage drinking
This would describe a premise like “drinking is wrong”, but the argument uses a correlation as support instead. The problem is assuming that this correlation establishes a causal link.
B
fails to consider that an alternative method of reducing underage drinking might be more effective
This is irrelevant because the conclusion is simply that this effort seems to be successful. It doesn’t matter if another method could be more successful.
C
infers from an association between pledging not to drink and refraining from drinking that the pledging was the cause of refraining from drinking
This describes the causation-correlation fallacy found in the argument. The premise only establishes a weak correlation between those who take the pledge and those who abstain from drinking, but assumes that this means the pledge is what’s causing people not to drink.
D
treats a condition that is sufficient to produce an outcome as though it were necessary for the outcome to occur
The argument doesn’t employ conditional reasoning to reach its conclusion. The conclusion identifies a supposed causal relationship, but is flawed because it only cites a weak correlation as support.
E
confuses the claim that many adolescents who do not drink report having taken the pledge with the claim that many who report having taken the pledge do not drink
These two claims are logically equivalent, so this doesn’t speak to the argument’s flaw. The argument’s problem is citing a weak correlation as evidence for a causal relationship.