Erich: Certainly not.
Leslie: Just as I expected! It is clear from your answer that your hands are more important to you than possessing the world. But your entire body is necessarily more important to you than your hands. Yet you are ruining your health and harming your body in your quest for a treasure that is much less valuable than the whole world. I rest my case.
Summarize Argument
Leslie tells Erich that his quest for treasure is irrational. She lays out her argument by demonstrating that Erich agrees that his hand is more valuable to him than possessing the world. She knows Erich’s body is more important to him than his hands, and that the treasure is less valuable than the whole world. However, Erich is harming his body by searching for treasure, which seems contrary to the assertion he agreed with. This makes his search irrational.
Identify Conclusion
The conclusion is what Leslie is trying to prove with her ‘case’: “your quest for the treasure is irrational.”
A
Erich would not sacrifice one of his hands in order to possess the world.
This is a statement that Leslie uses to prove that Erich’s quest is irrational.
B
Erich should not risk his physical well-being regardless of the possible gains that such risks might bring.
Leslie is not arguing “regardless of the gains.” She demonstrates that the gains would be less valuable to Erich than what he is losing.
C
Erich is irrationally risking something that is precious to him for something that is of no value.
Leslie does not claim that the treasure has “no value.” She instead shows he is losing something more valuable for something less valuable.
D
Erich can be convinced that his quest for the treasure is irrational.
Leslie is trying to convince Erich, but she is not claiming that he can be convinced. She employs her evidence to convince him, not to show that he is persuadable.
E
Erich is engaging in irrational behavior by pursuing his quest for the treasure.
This accurately rephrases Leslie’s conclusion. She structures her argument to show that Erich’s quest is irrational.
Summarize Argument
The author concludes that people who take vitamin C supplements tend to be healthier than average. This is because a study showed that people who regularly consume high doses of vitamin C supplements have a much lower than average risk of heart disease.
Notable Assumptions
The author assumes that taking vitamin C supplements doesn’t cause any harm to overall health that could outweigh the benefits of lower risk of heart disease. (Maybe vitamin C supplements lead to a higher risk of kidney disease? If so, we can’t conclude that people who take vitamin C supplements are healthier than average.)
A
Vitamin C taken in the form of supplements has a different effect on the body than does vitamin C taken in food.
The conclusion is about vitamin C supplements, and the study is also about vitamin C supplements. Whether vitamin C in food has different effects from vitamin C in supplements doesn’t affect the argument.
B
The reduction in risk of heart disease due to the consumption of vitamin C is no greater than the reduction due to certain other dietary changes.
The author never suggested eating vitamin C was the best way to reduce heart disease. There can be other dietary changes that reduce heart disease as much or more than vitamin C; this is consistent with the argument.
C
Taking both vitamin C supplements and vitamin E supplements lowers one’s risk of heart disease far more than does taking either one alone.
We know there’s a correlation between eating high doses of vitamin C supplements and having a lower risk of heart disease. The fact a combination of vitamins might reduce heart disease more doesn’t change the fact that there’s evidence vitamin C reduces heart disease risk.
D
High doses of vitamin C supplements tend to reduce slightly one’s resistance to certain common infectious diseases.
This points out a harmful effect of vitamin C supplements. This raises the possibility that this harmful effect might outweigh decreased risk of heart disease when it comes evaluating vitamin C supplements’ impact on overall health.
E
Taking vitamin C supplements has been found to lower one’s risk of developing cancer.
This is an additional benefit of vitamin C supplements. To weaken the argument, we want to point out a harm from vitamin C supplements.
Boris: It’s because, beginning in 1995, many people learned the merengue and several related ballroom dances. Because these dances are so popular, other ballroom dances are now catching on.
Summarize Argument
George asks why a large number of people are now taking ballroom dancing lessons, even though in the 1980s and 1990s, almost nobody took ballroom dancing lessons.
Boris’s answer is that in 1995, lots of people learned some ballroom dances, and this lead to other ballroom dances becoming popular.
Identify and Describe Flaw
George isn’t just asking “Why are lots of people taking ballroom dancing lessons?” He’s asking why so many people are taking ballroom dancing in light of the fact that it was unpopular in the past. In other words, George sees a discrepancy that needs to be explained.
Boris’s answer doesn’t help resolve the discrepancy. Pointing out that ballroom dancing started to become popular in 1995 doesn’t explain WHY it became more popular after a period of being unpopular.
A
show that the people who learned the merengue are the same people who are now interested in other ballroom dances
Boris didn’t need to show that the exact same people are now interested in other dances. Perhaps one person is inspired to dance because of a different person’s dancing. What Boris needed to explain was why ballroom dancing became popular, even though it was unpopular before.
B
explain why ballroom dancing was so unpopular before 1995
Boris didn’t need to explain why ballroom dancing was unpopular before 1995. He needed to explain how it became popular after 1995. There’s a difference between explaining why something used to unpopular and explaining why something became popular.
C
relate the merengue to the forms of dancing that were more prevalent before 1995
Boris didn’t need to relate the merengue to other kinds of dancing. The merengue is simply one kind of ballroom dance. What matters is why the merengue and other ballroom dances became popular in 1995.
D
account for the beginning of the revival of interest in ballroom dancing
Boris failed to explain why ballroom dancing started to become popular in 1995. George wasn’t just asking, “Why are lots of people interested in ballroom dance?” He asked what explains the unexpected new interest, given the lack of interest in the 80s and early 90s.
E
demonstrate that all types of ballroom dancing are currently popular
Boris didn’t need to show that all ballroom dancing types are popular. He just needed to explain why ballroom dancing in general became popular, despite its unpopularity in the 80s and early 90s.
Summary
Some scientists think that Neanderthals are a different species from Cro-Magnons (the ancestors of modern humans) because of relatively minor morphological differences.
Both groups of hominids used exactly the same kinds of tools even in different environments.
The two groups would have used the same tools only if they faced the same daily challenges and met them in the same way.
The behavioral similarity shown in the tool use suggests that the two groups were members of the same species and that the morphological differences were from living in different environments.
Notable Valid Inferences
Cro-Magnons and Neanderthals faced the same daily challenges and met them in the same way.
A
Morphological differences between the members of two populations do not guarantee that the two populations do not belong to the same species.
This could be true. The stimulus leaves open the possibility that two populations have morphological differences and are members of the same species.
B
The daily challenges with which an environment confronts its inhabitants are unique to that environment.
This must be false. We know that the two species lived in different environments, and we also can logically infer that they faced the same daily challenges and met them the same way (because species use the same tools only if they face the same daily challenges).
C
There are greater morphological differences between Cro-Magnons and modern humans than there are between Cro-Magnons and Neanderthals.
This could be true. The stimulus does not give any information that allows us to compare the extent of morphological differences between different species.
D
Use of similar tools is required if members of two distinct groups of tool-making hominids are to be considered members of the same species.
This could be true. Use of similar tools is given as a sufficient condition for facing the same daily challenges; there is no information that prevents use of similar tools from being a necessary condition for being the same species.
E
Through much of their coexistence, Cro-Magnons and Neanderthals were geographically isolated from one another.
This could be true. We know that the two species were living in different environments; it could be the case that they were geographically isolated.
Summary
The author concludes that he can skip the step of sprinkling live mussells with cornmeal.
Why?
Because mussels available at seafood markets are farm raised and don’t contain sand. Cornmeal is used to clean out sand in mussels.
Why?
Because mussels available at seafood markets are farm raised and don’t contain sand. Cornmeal is used to clean out sand in mussels.
Notable Assumptions
The author assumes that the mussels he’s about to prepare were obtained at a seafood market.
The author also assumes that there is no other reason cornmeal is used to clean live mussels out besides to get them to eject sand.
The author also assumes that there is no other reason cornmeal is used to clean live mussels out besides to get them to eject sand.
A
Cornmeal is not used to clean out farm-raised mussels before they reach seafood markets.
Not necessary, because even if cornmeal is used to clean out farm-raised mussels, the author is only arguing that he doesn’t need to use cornmeal. It may be that many people still use cornmeal when they don’t need to; that doesn’t undermine the argument.
B
Mussels contain no contaminants other than sand.
Not necessary, because other contaminants can be cleaned out by other steps. The author merely believes that he can skip the cornmeal step. But there may be other steps necessary to get rid of other contaminants.
C
Sprinkling the mussels with cornmeal does not affect their taste.
Not necessary, because we have no reason to think taste plays any role in the author’s reasoning. Let’s say cornmeal does affect taste — thta doesn’t suggest a reason the author can’t skip the cornmeal step.
D
The chef’s mussel recipe was written before farm-raised mussels became available.
Not necessary, because even if the recipe was written after farm-raised mussels became available, the recipe might have been assuming people didn’t have ready access to farm-raised mussels. In any case, the author’s argument is that he can skip a step in the recipe, so it’s not clear why he’d have to assume anything about when the recipe was written.
E
The mussels the chef is using for the mussel recipe came from a seafood market.
Necessary, because if it were not true — if the mussels the author is using are NOT from a seafood market — then the author can’t assume that the mussels do not contain sand. In other words, if (E) were not true, the author might not be able to skip the cornmeal step.