Journalist: When judges do not maintain strict control over their courtrooms, lawyers often try to influence jury verdicts by using inflammatory language and by badgering witnesses. These obstructive behaviors hinder the jury’s effort to reach a correct verdict. Whenever lawyers engage in such behavior, therefore, it is reasonable to doubt whether the verdict is correct.

Summarize Argument
A Journalist argues that it is reasonable to doubt whether a verdict is correct when judges do not maintain strict control over their courtrooms. Without such control, lawyers often use inflammatory language and badger witnesses, hindering the jury’s effort to reach a correct verdict.

Notable Assumptions
The Journalist assumes that lawyers often effectively influence jury verdicts through obstructive behaviors.
The Journalist also assumes that the impact of obstructive behaviors outweighs that of other evidence/testimony

A
Court proceedings overseen by judges who are very strict in controlling lawyers’ behavior are known to result sometimes in incorrect verdicts.
While this casts doubt on the reliability of trials with strict judges, it does not weaken the link between obstructive behaviors warranting being skeptical of the verdict.
B
Lawyers tend to be less concerned than are judges about whether the outcomes of jury trials are just or not.
It does not matter whether lawyers or judges are concerned with the outcomes of jury trials. The argument is focused on the impact of obstructive behaviors on the verdict
C
People who are influenced by inflammatory language are very unlikely to admit at some later time that they were influenced by such language.
It does not matter whether people *admit* that they were influenced by inflammatory language. The argument is focused on the *impact* of such language
D
Obstructive courtroom behavior by a lawyer is seldom effective in cases where jurors are also presented with legitimate evidence.
This undermines a key assumption: that the impact of obstructive behavior will outweigh legitimate evidence. If it is rarely effective in cases with legitimate evidence, the conclusion is severely weakened.
E
The selection of jurors is based in part on an assessment of the likelihood that they are free of bias.
The jury selection process is irrelevant to the argument’s reasoning. The argument is focused on the link between obstructive behavior and the verdict’s validity

5 comments

One should only buy a frying pan that has a manufacturer’s warranty, even if it requires paying more, and even if one would never bother seeking reimbursement should the pan not work well or last long. Manufacturers will not offer a warranty on a product if doing so means that they will need to reimburse many customers because the product did not work well or last long.

Summarize Argument
The author concludes that you should only buy a frying pan that has a manufacturer’s warranty, even if you wouldn’t seek reimbursement in the event the pan doesn’t work well or last long. This is because the fact that a manufacturer offers a warranty indicates that they won’t need to reimburse many customers due to the product failing to work well or failing to last long.

Notable Assumptions
The author assumes that the reason manufacturers who offer a warranty won’t need to reimburse customers is the quality of the frying pan. This overlooks the possibility that the reason manufacturers won’t need to reimburse customers is simply that customers tend not to seek reimbursement when the frying pan breaks or doesn’t work well.

A
Most people who buy a frying pan with a manufacturer’s warranty would seek reimbursement should the pan fail to work well or last long.
The provides evidence against the possibility that manufacturers offer a warranty merely because people tend not to seek reimbursement. This gets rid of the alternate explanation for why manufacturers offer a warranty, and it makes the premise more supportive of the conclusion.
B
All of the frying pans currently on the market that are covered by a manufacturer’s warranty work at least as well at the time of purchase as any of the frying pans not covered by a warranty.
This tells us that the warranty pans work at least as well as the non-warranty pans at time of purchase. But this doesn’t suggest we should “only” buy pans that are under warranty. Why not buy the non-warranty pans, too?
C
The more a frying pan costs, the more likely it is to be covered by a manufacturer’s warranty.
This identifies which pans are most likely to be under warranty. But it doesn’t suggest we should “only” buy pans under warranty, and doesn’t help connect the premise to the conclusion.
D
The most expensive frying pans are the ones most likely to work well for many years.
This doesn’t tell us anything about the pans under warranty or why we should “only” buy those pans.
E
Most frying pan manufacturers’ warranties provide for full customer satisfaction.
The author’s conclusion is that we should buy the pans under warranty even if we won’t seek reimbursement. So the offer of full satisfaction doesn’t matter; if we don’t seek reimbursement the level of satisfaction doesn’t affect what we would get.

Further Explanation

This is a Strengthening question.

Be careful not to mistake the question stem for a Most Strongly Supported question. In a Strengthening question, you are choosing an answer choice that adds to the support of the argument, while in an MSS question, you are taking the stimulus to be true and finding the answer choice that receives the most support.

Hopefully we got over that hurdle, but there are many more hurdles in the argument itself. You first have to understand how the “even if” is functioning in the stimulus as well as be able to take the contrapositive of the premise. However, this is not just an exercise in formal logic like an SA or a PSA question where you just map out the conditionals. In fact, this is actually more of a phenomenon-hypothesis question where the correct answer choice blocks an alternative hypothesis.

Let’s look at the stimulus. It says you should only buy a frying pan that has a manufacturer's warranty. That sounds like a command. And as if expecting an objection, the author says even if it requires paying a little bit more, I should still go for the warranty. But what if I am not the kind of person that would ever find the warranty form, fill it out, and mail it in? And as if the author had also anticipated this second objection, we are told that even if you would never bother seeking reimbursement should the pan not work, you still need to buy the pan with the warranty.

Do you see what the “even if” is doing? Imagine if the author had said that one should buy a frying pan that has a manufacturer's warranty, full stop. That full stop still completely anticipates any potential objections. So in a sense, the “even if” is not doing much. It is just reinforcing that you do not get out of this rule with these possible objections. If you are buying a frying pan, you'd better buy one with a manufacturer's warranty (buy pan → warranty).

And the premise to this conclusion is that manufacturers will not offer a warranty on a product if doing so means that they will need to reimburse many customers because the product did not work well or last long (reimburse many → no warranty). Let’s take the contrapositive of this. If a manufacturer does offer the warranty, then it is not the case that they need to reimburse many customers. (warranty → not reimburse many). And this is why you should only buy things with manufacturer's warranties. So the unstated assumption in this argument is that a manufacturer's warranty is an indicator of high quality, which means that not having to reimburse many customers is an indicator of high quality.

That is the unstated assumption, but let’s evaluate this assumption. Is it actually the case that not having to reimburse many customers is an indicator of high quality? This is where your phenomenon-hypothesis framework comes in. Let’s say All-Clad, an American manufacturer of frying pans, sells many frying pans but very rarely reimburses customers because of bad products. How do you explain this phenomenon?

One hypothesis might be that they make good products. It works well and lasts long, so not many customers seek reimbursement. And this is what the author presumes. But can you think of an alternative hypothesis? Maybe seeking reimbursement is a difficult process. You have to fill in a thousand different forms and call five different departments. Or maybe the particular market segment for frying pans is just too lazy, like me, to seek reimbursement. Both hypotheses would weaken the argument because now the fact that not very many people call in the warranties is no reflection on product quality.

Correct Answer Choice (A) says that most people who buy a frying pan with a manufacturer's warranty would seek reimbursement should the pan fail to work or last long. This wrecks the hypothesis above. (A) strengthens the argument by knocking out a couple of these competing hypotheses so that the product being high quality is more likely to be the hypothesis that explains the low reimbursements. (A) has identified precisely where the argument is vulnerable and patched it up. It has reaffirmed an assumption the argument already made.

Answer Choice (B) says that all of the frying pans currently on the market covered by warranty work at least as well at the time of purchase as any of the pans not covered by warranty. On first blush, you might think (B) strongly supports the conclusion because it seems to provide another reason to buy the warranty pans. But this is a pretty common trap the LSAT writers use in Strengthening questions, which is to come up with independent reasons to support the conclusion. Unlike (A), (B) does not address any of the premises or unstated assumptions and just independently supports the conclusion.

But if you examine (B) closely, you will see it does not even independently provide you with a reason to buy the pans with warranties. In order for (B) to independently support the conclusion, we need to assume that it is really bad if the non-warranty pans worked better than the warranty pans at the moment of purchase. If we make that assumption, then (B) helps by precluding that possibility. But we don't need to make that assumption. Would it actually be really bad if the non-warranty pans worked better than warranty pans at the moment of purchase? Frying pans are not disposable like plastic forks. Durability matters. So what I care about is whether the non-warranty pan can keep up its quality, because I know if the quality starts degrading on my warranty pan, I can return it. So maybe I care a little bit that non-warranty pans are better than the warranty pans at the time of purchase, but it is not nearly as important as it might initially have seemed.

(B) is analogous to trap answer choices in Weakening questions that look like they are contradicting the conclusion, but upon closer inspection, they do not. This is a Strengthening question so (B)'s trap is to give you something that looks like it is supporting the conclusion, but upon closer inspection, it does not.

Answer Choice (E) is similar to (B). (E) says most frying pans’ manufacturer’s warranties provide for full customer satisfaction. So (E) gives us yet another reason to buy a pan with a warranty. (E) might be a little bit better than (B) because it supports the conclusion more strongly, but (E) still shares the same flaw as (B), which is that it completely ignores the argument. (E) is not entirely irrelevant, just as (B) was not entirely irrelevant in that how good the pan is at the time of purchase surely matters some. But neither (E) nor (B) meaningfully engages with the argument.

Answer Choice (D) says the most expensive frying pans are the ones most likely to work well for many years. But this information is not helpful because we do not know if the most expensive frying pans have a warranty or not. The author only says that one should go for the warranty even if it requires paying more, and never says warranty pans actually do cost more or less.

Answer Choice (C) says the more a frying pan costs, the more likely it is to be covered by a manufacturer's warranty. I suppose (C) is better than (D) because it is at least correlating cost to warranty. But it still does not do much since the author already said to forget the costs. The author thinks a manufacturer's warranty is an indication of the product's quality, so harping on about costs is not going to affect the argument.


44 comments

Psychologist: Most people’s blood pressure rises when they talk. But extroverted people experience milder surges when they speak than do introverted people, for whom speaking is more stressful. This suggests that the increases result from the psychological stress of communicating rather than from the physical exertion of speech production.

Summarize Argument: Phenomenon-Hypothesis

The psychologist hypothesizes that increased blood pressure when talking is caused by the psychological stress of communicating, not the physical effort of speaking. She supports this by noting that, while most people’s blood pressure rises when speaking, extroverts experience smaller increases than introverts, for whom speaking is more stressful.

Notable Assumptions

The psychologist assumes that blood pressure increases from psychological stress, not physical effort, but doesn't provide any reason to rule out physical effort as being at least a part of the cause.

A
Medications designed to lower blood pressure do not keep the people who take them from experiencing blood-pressure fluctuations when speaking.

Irrelevant— we don’t know whether introverts or extroverts are taking more blood pressure medication. Regardless, the fact that the medication doesn’t reduce blood pressure increases caused by speaking does nothing to strengthen the argument.

B
In general, the lower one’s typical blood pressure, the more one’s blood pressure will increase under stress.

Irrelevant— we don’t know whether introverts or extroverts have a lower typical blood pressure. Either way, (B) is simply affirming that blood pressure increases under stress. It isn’t helping us to figure out why blood pressure increases while speaking.

C
Introverted people who do not have chronically high blood pressure often sense the rises in blood pressure that occur when they speak in conversation.

Irrelevant—whether some introverts notice their blood pressure rise while speaking doesn’t change the fact that it is rising. We need an answer that explains why it’s rising. Also, as far as we know, extroverts might notice the increase too.

D
Deaf people experience increased blood pressure when they sign, but no change when they move their hands for other reasons.

This suggests that physical exertion isn’t causing the blood pressure increase. Since deaf people’s blood pressure rises when they communicate through sign language, but not when they move their hands, it suggests the increase is due to communication, not physical movement.

E
Extroverted people are more likely to have chronically high blood pressure than are introverted people and are more likely to take medication to lower their blood pressure.

This weakens the argument by offering an alternative explanation for the difference in blood pressure between extroverts and introverts. If extroverts tend to have high blood pressure and take medication, the difference could be due to the medication, not stress.

This is a Strengthening question.

The psychologist's argument uses scientific reasoning, so we have a phenomenon and a hypothesis. The stimulus describes some observations, which can easily sound like an experiment. If interpreted as an experiment, it's a pretty badly designed experiment. So thinking about what controls we need to improve this "experiment," in other words, contrasting this with what an ideal experiment would look like, will help you solve this question.

The stimulus says most people's blood pressure rises when they talk, but extroverted people experience milder surges when they speak than do introverted people, for whom speaking is more stressful. So we have kind of a classic setup in the premise with two different groups of people and two different results. And the conclusion, or the hypothesis, is that this suggests that blood pressure increases result from the psychological stress of communicating rather than from the physical exertion of speech production.

This is strange. What if physical exertion is something that does affect blood pressure? It sounds reasonable to say that this might be a competing explanation that we would want to examine. If the psychologist had said that it is stress that causes blood pressure to increase and not, for example, the color of the hat someone is wearing, then sure. It makes sense that we would not examine the color of people’s hats since this is unlikely to affect blood pressure.

But the conclusion is ruling out physical exertion while the premise did not give us reasons to do so. In fact, physical exertion is not mentioned at all. And that is why this is a badly designed "experiment." It is not really even an experiment, but rather just an observation, as it does not control for physical exertion or anything else, for that matter. Imagine how weak this argument would be if introverts happened to physically exert more when they spoke than extroverts. Now not only does stress vary with blood pressure, physical exertion also varies with blood pressure. How can you say it is the stress, and not the physical exertion, that is causing the surge in blood pressure?

If you really wanted to figure out if it is psychological stress that causes increases in blood pressure, you would collect a bunch of people and randomly split them into two groups. You would not care if they were introverts or extroverts because these distinctions only mattered since they were thought to be good proxies for the speakers’ stress levels. The conclusion wasn't that introversion caused an increase in blood pressure. It was that stress caused the increase. And because the groups are totally random, people who do a lot of physical exertion and people who do not would be spread out across the two groups as well. Now you have controlled for physical exertion.

And then you intervene in one of the groups. It does not matter which one because they are equalized at the moment. You intervene by stressing out one of the groups as they speak (maybe by inducing conversation on controversial topics), and whatever differential blood pressure you observe, you can be pretty sure it was due to your psychological intervention. That is how you design an ideal experiment.

So you have two options if you want to strengthen this crappy argument. One option is to control for physical exertion: say that the amount of physical exertion is the same for both introverts and extroverts. Another is to say that physical exertion simply does not matter for blood pressure, just as the color of somebody’s hat does not matter.

Correct Answer Choice (D) strongly suggests that physical exertion doesn't matter. On first blush, (D) might seem irrelevant because it does not mention introverts, extroverts, or blood pressure. This is why I generally try not to anticipate answers in Strengthening or Weakening questions, especially in scientific reasoning. LSAT writers can always think of things I cannot think of, and I might be digging myself into a hole by trying to anticipate the answer.

(D) says deaf people experience increased blood pressure when they sign, i.e., communicate, but no change when they move their hands for any other reasons. So (D) is suggesting that it is not the physical exertion that is causing blood pressure to increase. If it were, you would expect to see an increase in both situations.

Do you see how physical exertion, while not equalized, has now at least been somewhat accounted for? (D) does not control for differences in physical exertion between the two groups (for example, it could still be the case that introverts move their hands more than do extroverts) but it does strongly suggest that even if there were differences in physical exertion, it would not be relevant, like the color of your hat.

So what is causing this blood pressure increase? In one situation, they are communicating, and in the other, they are not. So (D) is in fact also hinting that the stress attendant with communication might be causing blood pressure to increase. So (D) is great. Even with (D), you can still poke holes in the argument, but this is okay. In Strengthening questions, you just need to make the argument a little bit better.

Answer Choice (C) says introverted people who do not have chronically high blood pressure often sense the rises in blood pressure that occur when they speak in conversation. So there is a subset of introverts who do not have chronic high blood pressure, and this subset can sense their blood pressures go up. Maybe they feel flushed, dizzy, etc. This doesn't help the argument. Imagine if this group was not so sensitive and could not sense this increase. This would not change the fact that the blood pressure for this group still went up.

In addition, how does this group of introverts relate to introverts in general? And what about introverts who do have chronically high blood pressure? Are they as sensitive? What about extroverts who do or do not have chronic high blood pressure? (C) is silent on all of these questions and completely useless.

Answer Choice (E) is a little better than (C) in that at minimum, it is a comparison. (C) just told us something about a random subset of introverts, but (E) says extroverts are more likely to have chronically high blood pressure than are introverts. On top of that, extroverts are also more likely to take medication to lower their blood pressure.

So (E) is actually kind of relevant, and if anything, it is revealing another hole in the reasoning. It is telling us that extroverts are potentially carrying in this baggage that could undermine the conclusion. If extroverts are taking medication to lower their blood pressure, the observed difference in blood pressure between the two groups could just have been the result of this medication. (E) is offering a competing explanation for why the extroverts’ blood pressure did not go up as much. And I rarely say this, but if this were a Weakening question, I think (E) would actually be a great answer choice.

Answer Choice (A) is kind of interesting in its relationship to (E). (A) says medications designed to lower blood pressure do not keep people who take them from experiencing blood pressure fluctuations when speaking. We saw how (E) weakened the argument by presenting a potential alternative hypothesis. (A) is addressing this very weakness by saying that the extroverts’ medications do not prevent blood pressure surges. Maybe they are designed to just lower ambient levels of blood pressure and do not work when your blood pressure surges.

I do not think (A) is very relevant without its relation to (E), because when we consider (A) alone, we do not even know which group is taking this medication. So where (A) might be relevant is precisely when it saps energy away from (E). But notice how we are now just back to where we were in the beginning. The argument is not any stronger.

Answer Choice (B) says that in general, the lower one's typical blood pressure, the more one's blood pressure will increase under stress. Fair enough, but it seems like (B) is ignoring the argument and just reiterating the conclusion that stress makes your blood pressure go up. This is a classic wrong answer choice in Strengthening questions. It just leaves our argument as good or bad as it ever was.

First, we do not know who has the lower baseline blood pressure since the stimulus just said extroverts experience a milder surge than introverts. And even if we say that the higher surges for introverts were due to a lower baseline and milder surges for extroverts were due to a higher baseline, we are still left with the original hole in the argument. We do not know if it is the stress or the physical exertion that causes surges in blood pressure.


18 comments

This is a Necessary Assumption question.

The stimulus says that a new screening test detects certain polyps at such an early stage that it is generally unclear whether the polyps are malignant. But the risk that a polyp might be malignant leads doctors, in most cases, to have such polyps surgically removed, which is a dangerous process. Yet some of those polyps turn out not to be malignant. All of this is the premise and we have the conclusion in the following sentence. Thus, the new screening test can prompt dangerous operations that are not actually medically necessary.

This is a classic example of a bridging Necessary Assumption question. The first part of the conclusion is fine. Because the new screening test is what leads doctors to have polyps surgically removed, “prompting” is weak enough of a claim to be supported by the premise. But look at the part of the conclusion that says these operations are “not medically necessary.” What do we know about what is or is not medically necessary? This is the bit that needs to be bridged. The starting point of the bridge is the fact that some polyps turn out not to be malignant, and the end of the bridge is that these had better not be medically necessary.

Correct Answer Choice (B) acts as this bridge. It says surgical removal of nonmalignant polyps detected by the new screening test is not always medically necessary. This has to be true. Imagine if (B) were false and surgical removal of nonmalignant polyps was always necessary. Then this argument completely fails. In other words, it must be true that removing nonmalignant polyps sometimes is not necessary. That is the bare minimum in order for the premise to have any chance of supporting the conclusion.

Answer Choice (A) says a surgical operation that is dangerous is ethically justified only for treating a medical condition that is more dangerous. You should lose interest as soon as you see “ethically justified” because the argument here is not one of ethics. It is about whether the operations are necessary or not. Even if we assume that the medical condition is not more dangerous than the operation itself, the operation would then not be ethically justified since we failed the necessary condition. But so what? Whether this is ethical is not what the conclusion is arguing for.

Answer Choice (C) says if the new screening test encourages medically unnecessary operations, then probably it either should not be used or its use should be modified. I lost interest in the first half of (C), because again, the researcher tries to argue that the test is not medically necessary. We are trying to build a bridge from her premises to that conclusion, but (C) is assuming that the conclusion is already proven and building a bridge from the conclusion to some new territory.

Answer Choice (D) says a polyp detected by the new screening test should be surgically removed if it is malignant. Of course, remove it if it is malignant. This argument is about polyps that we do not yet know to be malignant. (D) is just giving us obvious instructions.

Answer Choice (E) says the screening test is medically useful only when it detects a polyp that requires treatment. Remember how we did not care whether an operation was ethically justified in (A)? Similarly, in (E), we do not care whether a screening test is medically useful. In addition, the stimulus does not tell us which polyps require treatment. So (E) is laying out a necessary condition that itself requires a bridge (e.g., polyps at risk of malignancy require treatment) in order to even connect to the stimulus. And even if you fail this necessary condition, at best, you find out that the screening test was not medically useful.


1 comment

This is a Necessary Assumption question.

The stimulus says recently discovered clay tablets from southern Egypt date to between 3,300 and 3,200 B.C. Though most of the tablets translated thus far are tax records, one of them appears to contain literary writing. All of this is premise supporting the conclusion.

And the conclusion is that these tablets challenge the widely held belief among historians that the Sumerian civilization in Mesopotamia was the first to create literature. So we used to think that the Sumerians were the first, and somehow these tablets challenge that, meaning the Egyptians predate the Sumerians. If you already spotted this assumption, you can just go hunting for the correct answer. But we’ll use process of elimination here.

Answer Choice (A) says most of the recently discovered tablets that have not yet been translated contain literary writing. So in the entire set of recently discovered tablets, there is a subset that has not yet been translated. And in that subset, most contain literary writing.

We do not need this to be true. We already have one of the tablets that contain literary writing and that is enough. Sure, having more would strengthen this argument, but we are just trying to find the necessary assumption. Running the negation test also helps. Say not most but rather just a few of the tablets contain literary writing. The argument does not fall apart.

Answer Choice (B) says every civilization that has kept tax records has also kept other written records. This is also not necessary. We are only talking about two civilizations, the Egyptian and the Sumerian. Why do we care if some other civilization like the Aztecs kept other written records? What does that have to do with this argument? Egypt still predates, or does not predate, the Sumerians in creating literature.

Correct Answer Choice (C) says historians generally believe that Sumerians did not create literature earlier than 3,300 B.C. This has to be true. Imagine if historians generally believed that the Sumerians did create literature earlier than 3,300 B.C., say 4,000 B.C. That is 6,000 years ago. And now we have this Egyptian tablet from 3,300 B.C., only 5,300 years old at best. How is this supposed to challenge the belief that Sumerians were the first to create literature? The Sumerians still predate the Egyptians by 700 years. That is why (C) is absolutely necessary.

Note that this question could have been way harder. Imagine if one of the other answer choices said historians generally believe that Sumerians first created literature between 2,800 B.C. and 2,700 B.C. This would be a super attractive answer choice. However, while this would certainly help the argument by definitively showing that Egyptian literature is older by about 600 years, it is not necessary. And you can see this is not necessary by changing the dates a bit, say 2,500 and 2,400 B.C. That would also help the argument. So it is not necessary that historians have to believe in the 2,800 to 2,700 B.C. date range.

Answer Choice (D) says some historians are skeptical about the authenticity of recently discovered tablets. This is not necessary. If anything, the skepticism only hurts the credibility of the argument. Necessary Assumption is part of the superset that we call Strengthening.

Answer Choice (E) says the Sumerian civilization arose sometime between 3,300 B.C. and 3,200 B.C. This is also not necessary. What if it instead arose between 2,800 and 2,700 B.C.? Falsifying, or negating, (E) does not ruin the argument. If anything, this version of falsification actually helps the argument. Egypt would clearly predate the Sumerians in this scenario because the Egyptian clay tablet would be dated to be 500 years older than the Sumerian civilization itself.


7 comments

Climatologist: The waters off the Pacific coast of North America have warmed about 4 degrees over the past 15 years. Some scientists claim that this trend is a symptom of a more general, global warming caused by human-generated air pollution. However, this conclusion is far from justified—it is known that there are many natural cycles of ocean temperature changes that last 60 years or more.

Summarize Argument: Counter-Position
Some scientists think that warming off the Pacific Coast of North America is due to global warming from human-generated air pollution. The author concludes that this belief is not supported. This is because there are many natural (non-human-generated) cycles of ocean temperature changes. The author is suggesting that because the warming might be explained by these natural cycles, we cannot conclude that it is due to global warming from human-generated air pollution.

Identify Conclusion
The conclusion is the author’s assessment of the lack of support for the view that the warming off the Pacific coast is due to global warming from human-generated air pollution: “[T]his conclusion is far from justified.”

A
Some scientists have found evidence that the waters off the Pacific coast of North America have grown significantly warmer over the past 15 years.
This is context. Some scientists propose a hypothesis for this warming. The author says that hypothesis is not justified.
B
The warming of the waters off the Pacific coast of North America is not a symptom of a more general, global warming caused by human-generated air pollution.
This goes too far. The author just says the belief that it is caused by global warming from human-generated air pollution is not justified. That doesn’t mean the author thinks it’s not the cause.
C
The conclusion that the warming of the waters off the Pacific coast of North America is a symptom of a more general, global warming caused by human-generated air pollution is far from justified.
This is a paraphrase of the conclusion.
D
The warming of the waters off the Pacific coast of North America may be the result of a natural cycle of ocean temperature changes.
This is part of the author’s support. Because the warming of the waters might be due to natural cycles, the author concludes that the belief the warming is caused by human-generated air pollution is not justified.
E
If the warming of the waters off the Pacific coast of North America is due to a natural cycle of ocean temperature changes, then it is not a symptom of a more general, global warming caused by human-generated air pollution.
This is an assumption underlying the author’s argument. Because the warming of the waters might be due to natural cycles, the author concludes that the belief the warming is caused by human-generated air pollution is not justified.

1 comment

Robin: Archaeologists can study the artifacts left by ancient cultures to determine whether they were nomadic or sedentary. If the artifacts were made to last rather than to be quickly discarded, the culture was likely sedentary.

Kendall: But what artifacts a people make is determined largely by the materials available to them.

Speaker 1 Summary
Robin argues that archaeologists can determine if ancient cultures were nomadic or stayed in one place based on their artifacts. How is this possible? Well, long-lasting artifacts indicate a sedentary culture, whereas artifacts made to be quickly thrown away indicate nomads.

Speaker 2 Summary
Kendall comes to the unstated conclusion that artifacts’ longevity is not a good indicator of whether an ancient culture was nomadic or sedentary. This conclusion is supported by Kendall’s claim that peoples decided what artifacts to make based on the available materials, not their lifestyles.

Objective
We’re looking for a disagreement between Robin and Kendall. The two speakers disagree about whether a culture’s lifestyle can be reliably indicated by the durability of their artifacts.

A
the distinction that Robin makes between two kinds of cultures is illicit
Neither speaker makes this claim. Kendall disagrees with Robin about how useful artifacts are in making this distinction, but never takes issue with the underlying distinction between nomadic and sedentary cultures.
B
it is reasonable to assume that a culture whose artifacts were not durable was nomadic
Robin agrees and Kendall disagrees: this is their disagreement. Robin claims that durable artifacts are from sedentary cultures and non-durable artifacts from nomadic cultures. Kendall’s argument undermines the connection between artifact durability and cultural classification.
C
any evidence other than the intended durability of a culture’s artifacts can establish conclusively which of the two kinds of cultures a particular culture was
Neither speaker offers an opinion about this. Both Robin and Kendall focus entirely on what can be determined based on the durability of artifacts. Neither mentions other types of evidence.
D
the distinction that Robin makes between the different kinds of cultures is as important as many archaeologists have thought
Neither Robin nor Kendall talk about the importance of distinguishing between nomadic and sedentary cultures. Their discussion is about the use of artifacts when classifying cultures this way, not the merit of the classification.
E
studying a culture’s artifacts can reveal a great deal about the culture
Neither speaker offers a clear opinion about this. Robin thinks that artifacts can reveal a culture’s lifestyle, and Kendall thinks that artifacts are linked to available materials. However, we don’t know what counts as a “great deal” of information.

9 comments

Railroads rely increasingly on automation. Since fewer railroad workers are needed, operating costs have been reduced. This means that we can expect the volume of freight shipped by rail to grow. The chief competitor of railway shipping is shipping by truck, and no reduction in operating costs is predicted for the trucking industry.

Summarize Argument
The author concludes that we can expect the volume of freight shipped by rail to increase. This is because railroads have had reduced operating costs, whereas the main competitor to railway shipping (trucking) is not predicted to have reduced operating costs.

Identify Conclusion
The conclusion is the author’s prediction for what will happen to the volume of rail freight shipping: “[W]e can expect the volume of freight shipped by rail to grow.”

A
The volume of freight shipped by rail can be expected to increase.
This is a restatement of the conclusion.
B
Increasing reliance on automation means that fewer railroad workers are needed.
This is part of the support. Because fewer railroad workers are needed, the railroad industry has reduced operating costs. The author uses this support a prediction about an increase in the volume of rail freight.
C
No reduction in operating costs is predicted for the trucking industry.
This is a premise. The author uses the lack of reduced operating costs in a competitor industry to support a prediction about the increase in rail freight.
D
Operating costs for railroads have been reduced as a result of increased reliance on automation.
This is part of the support. Because of the reduced operating costs, the author predicts an increase in rail freight.
E
The chief competitor of railway shipping is shipping by truck.
This is a premise. The author points out that rail’s chief competitor isn’t predicted to have reduced operating costs to support the prediction that rail freight volume will increase.

1 comment

In the past, infants who were not breast-fed were fed cow’s milk. Then doctors began advising that cow’s milk fed to infants should be boiled, as the boiling would sterilize the milk and prevent gastrointestinal infections potentially fatal to infants. Once this advice was widely implemented, there was an alarming increase among infants in the incidence of scurvy, caused by vitamin C deficiency. Breast-fed infants, however, did not contract scurvy.

Summary
In the past, infants who were not fed breast milk were fed cow’s milk. However, once doctors began to recommend boiling the milk to sterilize it, there was a major increase in infants with scurvy, which is caused by vitamin C deficiency. However, breastfed infants did not show any increase in scurvy cases.

Strongly Supported Conclusions
Boiled cow’s milk reduces the amount of vitamin C present in milk.

A
Boiled cow’s milk makes less vitamin C available to infants than does the same amount of mother’s milk.
There was no difference in scurvy rates between infants fed cow’s milk and breastmilk until doctors recommended boiling cow’s milk. Thus, it is likely that boiling the milk reduced the amount of vitamin C.
B
Infants who consume cow’s milk that has not been boiled frequently contract potentially fatal gastrointestinal infections.
Nothing in the stimulus gives the rate at which infants contract infections. While the stimulus mentions the potential for infections, nothing says they are frequent.
C
Mother’s milk can cause gastrointestinal infections in infants.
There is no evidence linking breastfed milk and infections in infants anywhere in the stimulus.
D
When doctors advised that cow’s milk fed to infants should be boiled, they did not know that scurvy was caused by vitamin C deficiency.
The stimulus does not provide any information about what doctors believed about scurvy or vitamin C.
E
When doctors advised that cow’s milk fed to infants should be boiled, most mothers did not breast-feed their infants.
The stimulus does not give any information about what “most” mothers were doing at the time. This is too much of an assumption to make.

9 comments

The only effective check on grass and brush fires is rain. If the level of rainfall is below normal for an extended period of time, then there are many more such fires. Yet grass and brush fires cause less financial damage overall during long periods of severe drought than during periods of relatively normal rainfall.

"Surprising" Phenomenon
Why do grass/brush fires cause less financial damage overall during long periods of lack of rain than during periods of normal rainfall, even though there are a lot more fires when rainfall is below average for long periods?

Objective
The correct answer should differentiate periods of no rain from periods of average rain in a way that could lead to less overall financial damage from grass/brush fires during periods of no rain.

A
Fire departments tend to receive less funding during periods of severe drought than during periods of normal rainfall.
This deepens the discrepancy. If fire departments get less money during severe droughts, we would expect even more fires or even more intense fires during droughts, which should lead to more financial damage.
B
Areas subject to grass and brush fires tend to be less densely populated than areas where there are few such fires.
This compares areas subject to fires to areas with few such fires. But we’re not trying to explain a discrepancy between areas. Even in areas where there are typically few fires, we’d still expect more financial damage from fires during droughts.
C
Unusually large, hard-to-control grass and brush fires typically occur only when there is a large amount of vegetation for them to consume.
It’s reasonable to think there’s less vegetation during droughts. So, (C) suggests there would be fewer large, hard-to-control grass fires during a drought than during average rainfall. This could be why there’s less financial damage from grass fires during long droughts.
D
Grass and brush fires that are not caused by human negligence or arson tend to be started by lightning.
We already know that there are more grass/brush fires during periods of long drought than during periods of average rainfall. The cause of these fires, whether human negligence or lightning, doesn’t suggest we’d see less financial damage from fires during a drought.
E
When vegetation is destroyed in a grass or brush fire, it tends to be replaced naturally by vegetation that is equally if not more flammable.
This fact would apply equally to both the long drought period and the average rainfall period. So we’d still expect fires during the long drought periods to cause more damage overall, since there are more fires during these periods.

36 comments