"Surprising" Phenomenon
How could lightning have produced the first amino acids on Earth, even though Earth’s atmosphere at that time had a lot of oxygen, and amino acids break apart unless the spark that produced them occurs in an atmosphere that has a lot of hydrogen and not much oxygen (a “reducing” atmosphere)?
Objective
The correct answer should explain how there still could have been a “reducing” atmosphere necessary to allow the first amino acids to form and persist, even though Earth’s atmosphere had a lot of oxygen (and so was not a “reducing” atmosphere).
A
Meteorite impacts at the time life began on Earth temporarily created a reducing atmosphere around the impact site.
This raises the possibility that lightning could have produced amino acids around the impact sites of meteors, which temporarily had a reducing atmosphere.
B
A single amino acid could have been sufficient to begin the formation of life on Earth.
This doesn’t address how an amino acid could have formed and avoided breaking apart in an atmosphere that wasn’t reducing. If there was no reducing atmosphere, how would that single amino acid have come about?
C
Earth’s atmosphere has changed significantly since life first began.
The current atmosphere doesn’t matter, since the stimulus tells us Earth’s atmosphere “was” - meaning, at the time of the first amino acids - rich in oxygen. So, if the atmosphere wasn’t reducing, how could the amino acids form and avoid breaking apart?
D
Lightning was less common on Earth at the time life began than it is now.
But if there was lightning, however rare it was, how could that have produced amino acids in a non-reducing atmosphere? This doesn’t provide a theory about how this happened.
E
Asteroids contain amino acids, and some of these amino acids could survive an asteroid’s impact with Earth.
We’re interested in explaining how lightning could have produced the first amino acids. It doesn’t matter whether asteroids could have already had amino acids. Those aren’t amino acids produced by lightning on Earth.
Summarize Argument: Counter-Position
Terrence Gurney is incorrect in believing that he has not received sufficient credit for his literary achievements because his books are popular with a wide audience. It is more likely that Gurney has not received much praise for literary achievement because his writing is flat and leaves no lasting impression on the reader.
Identify Conclusion
The stimulus's conclusion is the author's opinion that Terrence Gurney is mistaken. Specifically, the author concludes that Gurney is wrong in thinking he hasn't received enough credit for his literary achievements simply because his books appeal to a wide audience.
A
Terrence Gurney is mistaken when he suggests that the wide appeal of his books has prevented him from being given due credit for his literary achievements.
This reflects the main conclusion that Terrence Gurney is operating under an incorrect belief. The stimulus supports this by providing an alternative reason for why Gurney has not received literary praise, stating that Gurney’s writing is flat and leaves no lasting impression.
B
Terrence Gurney’s books are not significant literary achievements.
This misstates a claim in the argument’s context. The author notes that Gurney believes he hasn’t received enough credit for his literary achievements. However, (B) incorrectly interprets this as a claim that Gurney’s books are objectively not significant literary achievements.
C
Even though Terrence Gurney’s books tell interesting stories, his writing is flat and leaves no lasting impression on the reader.
This restates a premise. The author cites Gurney’s flat writing and lack of lasting impression to support the conclusion that Gurney is mistaken about why he hasn't received credit for his literary achievements. Since this supports another claim, it can’t be the main conclusion.
D
Terrence Gurney has not been given due credit for his literary achievements because his books appeal to such a wide audience.
This statement is context. It describes Gurney’s belief, which the author disputes. By explaining Gurney’s belief, this context provides the background needed to understand the author’s counterargument that Gurney’s belief is incorrect.
E
Terrence Gurney should have received some praise for his literary achievements despite the fact that his writing is flat and leaves no lasting impression on the reader.
This is not a claim made in the argument. The author simply explains why Gurney has not received praise for his literary achievements. The author does not discuss whether Gurney’s lack of praise is deserved or not.
Summarize Argument: Phenomenon-Hypothesis
The manager concludes that the policy change caused the increase in mail-order sales. He supports this by noting that mail-order sales increased 25%, starting around the time the company began offering free shipping on all orders, instead of just on orders over $50.
Notable Assumptions
The manager assumes that there are no alternative hypotheses to explain the observed correlation— that is, he assumes there’s no other explanation for the recent increase in mail-order sales, like increased online ordering across companies or increased advertising.
A
Mail-order sales have been decreasing for companies that do not offer unlimited free shipping.
This rules out the alternative hypothesis that mail-order sales have also increased across other companies. It also strengthens the causal connection between unlimited free and increased mail-order sales by suggesting that without it, such sales may not increase.
B
The company did not widely advertise its change in policy.
This weakens the argument by suggesting that many customers didn’t know about the company’s unlimited free shipping. If they didn’t know about it, it’s unlikely that it influenced their mail-order purchases.
C
The company’s profits from mail-order sales have increased since the change in policy.
Irrelevant. The manager only addresses an increase in mail-order sales, not an increase in profits from mail-order sales. The fact that profits increased doesn’t help to establish that the policy change caused the increase in sales.
D
The company’s change in policy occurred well after its competitors started offering unlimited free shipping.
Irrelevant. Even if other companies have been offering unlimited free shipping much longer, we still need to determine whether unlimited free shipping caused the increase in mail-order sales at the manager’s company.
E
Most companies offer free shipping only on mail-order purchases over $50.
Irrelevant. Even if most companies don’t offer unlimited free shipping, we still need to determine whether unlimited free shipping caused the increase in mail-order sales at the manager’s company.
The author argues that publishing scholarly journals is likely much more profitable now than in the past. She supports this by pointing out that university libraries are paying much higher subscription rates, while the costs of publishing remain the same.
Notable Assumptions
The author assumes that publishers’ profits have increased just because one subset of their consumers’ are paying more. She ignores the possibility that other streams of revenue have remained unchanged or have decreased.
A
Many university libraries have begun to charge higher and higher fines for overdue books and periodicals as a way of passing on increased journal subscription costs to library users.
We are concerned with the profits of publishing companies, not libraries. We thus need an answer choice that weakens the conclusion that publishing companies’ profits have increased. (A) tells us instead what libraries are doing in response to increased costs.
B
A university library’s acquisition budget usually represents only a small fraction of its total operating budget.
Like (A), this is discussing the budget and costs of university libraries. But we are only concerned with the revenue and profits of publishing companies.
C
Publishing a scholarly journal is an expensive enterprise, and publishers of such journals cannot survive financially if they consistently lose money.
The cost of publishing a scholarly journal is irrelevant. We know that publishing costs have remained constant either way, so this doesn’t weaken the author’s conclusion that publishers’ profits have increased due to increased subscription costs for university libraries.
D
Most subscribers to scholarly journals are individuals, not libraries, and the subscription rates for individuals have generally remained unchanged for the past several years.
This weakens the argument by showing that the author’s key assumption is false. Because most subscribers are individuals whose subscription rates haven’t changed, it’s not the case that publishing a scholarly journal is much more profitable now than it was several years ago.
E
The majority of scholarly journals are published no more than four times a year.
This does not weaken the author’s conclusion that publishers’ profits have increased due to increased subscription costs for university libraries. The frequency of journal publications is irrelevant because we are only talking about the publishers’ profits.
Tamara: That is not true. Many wealthy Japanese during the Tokugawa period had their houses constructed with intentionally squeaky floors so that they would receive warning if a ninja were in the house.
Summarize Argument
Tamara concludes that it is not true that most Japanese people did not fear ninjas during Japan’s Tokugawa period. She bases this on the fact that, during the Tokugawa period, many wealthy Japanese people installed intentionally squeaky floors in their homes so that they would know if a ninja snuck in.
Notable Assumptions
Tamara assumes that wealthy Japanese people during the Tokugawa period are a representative sample of most Japanese people at that time. She assumes that, just because many wealthy people seem to have feared ninjas, that means that most other Japanese people also feared ninjas.
A
Many poor Japanese during the Tokugawa period also had houses constructed with intentionally squeaky floors.
This strengthens Tamara’s argument slightly by showing that more than just wealthy Japanese people appear to have feared ninjas. We instead need an answer choice that weakens her conclusion that most Japanese people feared ninjas in the Tokugawa period.
B
As part of their secret training, ninjas learned to walk on squeaky floors without making a sound.
Even if their squeaky floors weren’t an effective defense against ninjas, wealthy Japanese people still seem to have feared them. The questions remains whether these wealthy Japanese accurately represented all Japanese people during the Tokugawa period.
C
The wealthy made up a small portion of Japan’s population during the Tokugawa period.
This weakens the argument by showing that Tamara's assumption that wealthy Japanese accurately represent all Japanese people is false. (C) points out that Tamara can't draw a conclusion about all Japanese people in the Tokugawa period based only on evidence about wealthy people.
D
The fighting prowess of ninjas was exaggerated to mythic proportions in the years following the Tokugawa period.
Whether or not ninjas were truly great fighters doesn’t change the fact that many wealthy Japanese people seem to have been afraid of them during the Tokugawa period. (D) doesn’t weaken Tamara’s conclusion or point out that her assumption is false.
E
There were very few ninjas at any time other than during the Tokugawa period.
Tamara’s conclusion is only about Japanese people during the Tokugawa period, so the presence or absence of ninjas at any other time period is not relevant.
Summarize Argument: Counter-Position
The argument discusses a famous artist's claim that all great art imitates nature. However, the author points out that most great music does not imitate anything, such as ocean waves or animal sounds. Because of this, the argument concludes that either:
The artist’s claim is incorrect, or most great music is not actually great art since it doesn’t imitate nature.
The artist’s claim is incorrect, or most great music is not actually great art since it doesn’t imitate nature.
Identify Conclusion
The artist’s claim is incorrect, or most great music is not actually great art since it doesn’t imitate nature.
A
Music is inferior to the other arts.
The author does not say whether certain kinds of art are inferior to others. This argument is solely focused on the famous artist’s claim.
B
Either the artist’s claim is incorrect, or most great music is not great art.
This reflects the conflict between the famous artist’s claim and the premise that most great music does not imitate nature. Thus, either the famous artist is wrong, or most music is not great art because it does not imitate nature.
C
Like some great music, some great painting and sculpture may fail to imitate nature.
The argument does not talk about painting or sculpture. It is focused on the relationship between great art and music.
D
Some elements of nature cannot be represented adequately by great art.
This is not discussed in the argument and does not receive any support. The argument centers on what conclusions can be drawn from famous artist’s argument, given that most great music does not imitate anything at all.
E
Sounds that do not imitate nature are not great music.
The author directly contradicts this by acknowledging that most great music does not imitate nature. The famous artist *may* believe this, but it is certainly not the main conclusion of this argument.