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.

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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.

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This is a Weakening question.

The journalist says 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. And these obstructive behaviors hinder the jury's efforts to reach a correct verdict. Therefore, whenever lawyers engage in such behavior, it is reasonable to doubt whether the verdict is correct.

Does the conclusion follow? We know obstructive behaviors hinder the jury's effort to reach a correct verdict. But hinder isn't the same thing as prevent. That assumes the hindrance is effective. It's possible that the hindrance prevents the jury from reaching a correct verdict but it's also possible that the hindrance is simply an annoyance, something that the jury can shrug off. The point is that to hinder is just that, to hinder. It's not as dispositive as the argument wants us to believe.

Answer Choice (A) says court proceedings overseen by judges who are strict in controlling lawyers' behaviors are known to result sometimes in incorrect verdicts. I am already not interested in (A) because the argument is contemplating a specific situation where judges do not maintain control over their courtrooms. (A) does not engage with this premise and tells us that in a different world where judges do control their courtrooms, juries also reach wrong verdicts.

To make (A) better, we can edit the conclusion to say that only when lawyers engage in such behavior is it reasonable to doubt the veracity of the verdict. This version of the conclusion is saying that when we have a reason to doubt a verdict, it must be because of obstructive behavior. And (A) would weaken by illustrating a counterexample: juries mess up even when lawyers do not engage in obstructive behavior.

You will see a very similar cookie-cutter wrong Answer Choice (B) in Question 24 of this section, which also tells you to forget the situation at hand and talks about a different world. Just as you find patterns that repeat in the stimulus and correct answers, you will find recurring patterns in the wrong answer choices as well.

Answer Choice (B) says lawyers tend to be less concerned than are judges about whether the outcomes of jury trials are just or not. This is a comparative claim and somewhat obvious. We have an adversarial system where lawyers are concerned about winning and judges are concerned about justice. At best, (B) explains why lawyers have to be kept in check because they are not so concerned about justice.

Answer Choice (C) says people who are influenced by inflammatory language are very unlikely to admit they were influenced by such language. Let’s give (C) a charitable reading and say that the people influenced by inflammatory language here are the jurors. But even with this reading, (C) does not weaken the argument. If jurors were influenced, it does not matter if they are humble or reflective enough to admit that they were. If anything, (C) just tells us that this hindrance might actually lead to reasonable doubt about the verdict.

Answer Choice (E) says the selection of jurors is based in part on an assessment of the likelihood that they are free from bias. This is true in reality. For example, in a corporation versus an individual case, you would want jurors who are not already biased against corporations. However, the argument is not about bias. (E) would have been better if it said the selection of jurors is based in part on an assessment of the likelihood that they are free from being influenced by inflammatory language.

But even then, (E) would not be a great answer choice because it is denying the premise that obstructive behaviors do hinder the jury's effort to some extent. And while you do sometimes see explicit contradictions to a premise in the LSAT, this is generally not how the test writers weaken arguments.

Correct Answer Choice (D) says obstructive courtroom behavior by a lawyer is seldom effective in cases where jurors are also presented with legitimate evidence. This is the only answer choice that addresses the gap between the premise and the conclusion.

Remember we said that just because obstructive behaviors hinder the jury's efforts, we cannot assume that this hindrance is effective. And (D) confirms this. It says there's this other factor, legitimate evidence, that renders obstructive behaviors ineffective.

You might object and say (D) requires an assumption that cases where jurors are presented with legitimate evidence are most cases, or at minimum, the cases where lawyers engage in obstructive behaviors. But this is not an unreasonable assumption. We have a functioning judicial system with robust rules of evidence, and in the vast majority of cases, there is legitimate evidence. You might think it is unfair to be expected to know this, but what you are expected to know is how to identify the assumption that (D) requires and compare it to assumptions required by the other answer choices. While (D) may not be the perfect answer choice, it still is the best answer choice.

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This is a PSA question.

Mateo says global warming has caused permafrost to melt under several arctic villages, forcing all of their inhabitants to relocate at great expense. Then he says that pollution from automobiles is a major contributor to global warming (another premise). Now he's given us a causal chain starting with automobiles and leading to pollution, then global warming, then melting permafrost, and finally, expensive relocation. Here comes the conclusion: the automotive industry should be required to help pay for the villagers' relocation. We have descriptive causal premises leading to a prescriptive conclusion.

In PSA questions, we have the premise (P) and the conclusion (C) and are generally looking for a P → C "rule." And the reason the question stem includes the word "principle" is that the P → C could be stated in terms more general than what you see in the answer choices. And there is a large degree of freedom in how general they will be.

For example, the correct answer could generalize a lot and say any "entity" whose "actions" have some negative consequence must pay for the cost of that consequence. You can take this general principle and apply it to this argument, but you can also apply it to a bunch of other arguments. The correct answer could generalize less and say if an "industrial product" has some negative downstream consequences, then the "manufacturer" must pay to cover the costs of those consequences. This one would apply to a smaller set of arguments than the more generalized principle of entities.

Most PSA questions lay out recurring traps. We find one such trap, that of starting the bridge at the conclusion in Answer Choice (E). It says an industry that contributes to global warming should be required to pay for resulting damage to specific communities only if it has a general obligation to help pay for all damage produced by global warming.

An industry being required to pay is the desired conclusion. So that concept cannot be in the sufficient condition. At best, this rule allows the stimulus to fail the necessary condition (say we had a premise that amounted to the auto industry not having a general obligation to help pay for all damage), therefore concluding the failure of the sufficient (auto industry should not be required to pay for damage to specific communities). That's not what we want. This answer choice is logically wrong.

(E) would have been correct if it said an industry that contributes to global warming should be required to help pay for resulting damage to specific communities, full stop.

Correct Answer Choice (D) says any industry manufacturing a product whose use contributes to costly damage for others should be liable for damages generated by that product's use. This is the P → C rule. The information in our premise triggers the sufficient conditions: any industry (automobile) manufacturing a product (cars) whose use contributes to costly damage (melting-permafrost-induced relocation) for others (arctic villagers). Hence, we can draw the necessary condition as the conclusion: the automotive industry should be liable for damages.

Answer Choice (A) says any industry has an obligation to pay for any damage that it should have known would result from its activities. (A) is pretty good if you strike out “it should have known.” But as it stands, that condition doesn't match the premise and so the sufficient condition in (A) does not trigger. While it might be common sense that cars generate pollution, the long causal chain in the stimulus makes it less reasonable to say that the automotive industry should have known about the results of their activities on arctic villages. (A) exhibits the recurring defect of starting the bridge at the wrong location.

Answer Choice (B) says manufacturers should be required to produce goods in a way that minimizes harm to people and the environment. (B) just tells the automotive industry to change the way it produces cars, but does not help the villagers get paid. This rule delivers the wrong results. Also a recurring defect.

Answer Choice (C) says when the use of a product causes damages, governments should not be required to pay for the damage unless those responsible for manufacturing the product are also required to pay. (C) is saying that if the government is required to pay, then it must be that manufacturing is required to pay. Or, contrapositive, if the manufacturer isn't required to pay, then neither is the government.

This is a strange principle to talk about when you are trying to get arctic villagers paid. Maybe (C) thinks Mateo’s next argument is to petition the government to compensate these villagers, and it is saying that if you want the government to pay, you must first establish that manufacturing has to pay. How bizarre.

This rule also exhibits the recurring defects of failing to match the premise and failing to match the conclusion.

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This is a Flaw/Descriptive Weakening question.

Lindsey says several people claim that our company was unfair when it failed to give bonuses to the staff. She suggests that perhaps they recalled that the company had promised that if it increased its profits over last year’s, the staff would all get bonuses. However, the company's profit was much smaller this year than it was last year. And the conclusion is that clearly, then, the company acted fairly.

Did the company act fairly? Well, the company promised that if profits increased, staff would get bonuses. Profits did not increase, so that promise just falls away. Sufficient failed, rule disappears.  So what is clear is that the company did not contradict this promise. But that doesn't mean the company acted fairly. That's a much broader claim.

Let’s also look at why people are claiming that the company acted unfairly. Lindsey suggests that they are claiming this because of the promise above. Okay, if that's the case, then they do not have a good claim since the company did not contradict this promise. But if they are claiming that the company acted unfairly for some other reason, then Lindsey is now the one making a flawed argument. The fact is we actually don't know why they are claiming that the company acted unfairly. If you spotted this, you can go hunting for the right answer choice. If not, you can use the process of elimination.

Correct Answer Choice (B) says the argument infers (conclusion descriptor) that an opinion is false merely because (premise descriptor) one potential reason for that opinion has been undermined. Exactly. Lindsey does successfully undermine a potential reason in her premises, but we do not know if people are claiming the company was unfair for that specific reason. That's why Lindsey's inference that the people's opinion is false (that the company didn't act unfairly) is flawed.

Answer Choice (A) says the argument relies on the opinions of certain unnamed people without establishing that those people were well informed on the matter. Sure, people are unnamed here, but Lindsey is not relying on their opinion to make her argument. If anything, she is contesting their opinion. Establishing that those people were well informed on the matter would be important only if Lindsey were trying to make an appeal to those people's authority, like if those people were subject matter experts.

An argument guilty of (A) would look something like the following. The company promised that if profits increased, staff would get bonuses. However, some people told me that profits did not increase. Note how this is different from Lindsey stating that the company’s profit did not increase as a fact. In the former case, it was merely an opinion of some unnamed people, and so to take that opinion as establishing the fact of the matter, we need to know who they were. Like if the CFO told her this, then it's more likely to be true. But if it was just some random employee, then we might be skeptical.

Answer Choice (C) says the argument dismisses (conclusion descriptor) a claim on the basis of (premise descriptor) certain irrelevant attributes of the people who made the claim. While the argument does dismiss the claim that the company acted unfairly, its premise does not say that these people have certain irrelevant attributes.

Here is an example guilty of (C)'s description. "We should pay no attention to the people claiming that the company acted unfairly. This is obvious when you consider that they wore red hats." This would be dismissing a claim on the basis of irrelevant attributes of the people making the claim. That's a specific version of attacking the source of the argument.

Answer Choice (D) says the argument confuses the size of a quantity with the amount by which that quantity has increased. What does this even mean? Say the size of a quantity is a hundred units. But it was originally thirty units. So it increased by seventy units. So I am confusing the hundred units with the seventy-unit increase? How is that even relevant to Lindsey's argument?

I think (D) attempts to lure you in simply by mentioning "quantity" and "increase" and the stimulus said something about profits being larger or smaller.

(D) might be more relevant if we made some major modifications to the stimulus. The sufficient condition in the promise was straight up failed because the company’s profit this year being smaller than last year's means that the company's profits did not increase. But let's change that. The edited promise reads "If the company had any profits at all this year, the staff would get bonuses." And we'll keep the facts the same: the company's profit was much smaller this year than it was last year.

Still a bit of a stretch, but this makes (D) a bit more relevant. Under this modified stimulus, the sufficient condition is triggered by the facts because even if the company’s profits decreased this year, the company still has positive profits. The comparison to last year's profits isn't relevant. And if Lindsey argues that the sufficient condition wasn't met, then she may be confusing a comparative quantity (this year's smaller profit versus last year's larger profit) with an absolute quantity (that there was any positive profit at all).

Answer Choice (E) says the argument overlooks the possibility that a policy can be fair even when it is not generous. I guess Lindsey overlooked this, but so what? (E) would be relevant if people claimed the company was not generous and Lindsey responded that the company was fair. But no such confusion takes place.

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This is a Parallel Method of Reasoning question.

The stimulus says the railway authority inspector who recently thoroughly checked the tracks testified that they were in good condition. The next claim says, “Thus, since” which means we’re about to get a premise followed by a conclusion. Since the inspector has no bias in the matter (premise), we should thus be suspicious of the newspaper reporter's claims that the tracks are in poor condition (conclusion).

Two people disagree about the condition of the railroad tracks. The argument is that we should believe the inspector, not the reporter. Why? Because the inspector has no bias and said the tracks were in good condition after having thoroughly checked them. The reasoning here is an appeal to authority. Let's now look at the answers and try to match the reasoning above.

Answer Choice (A) says my pottery instructor says that making pottery will not cause repetitive-motion injuries if it is done properly. So far, there seems to be a parallel between the pottery instructor and the inspector. Now we have to find somebody who disagrees and then conclude that we should believe the pottery instructor. But then (A) instead says, “I will probably not get such injuries, for whenever I do pottery, I use the proper techniques that my instructor taught me.” While this argument is fine, it is not analogous to the argument in the stimulus.

Answer Choice (B) says Gardner, a noted paleontologist who has no vested interest in the case, assures us that the alleged dinosaur bones are not old enough to be dinosaurs. Gardner, a relevant expert, is analogous to the inspector. Gardner also has no vested interest in the case, so he has no bias.

(B) goes on to say that we should be skeptical of Penwick's claims to have found dinosaur bones, for Gardner inspected the bones carefully. Gardner’s careful inspection is analogous to the inspector’s thorough check, and Penwick is analogous to the newspaper reporter. And the conclusion is that we should be skeptical of Penwick, which is similar to how we should be suspicious of the reporter. (B) matches the stimulus extremely well. The reasoning here is also one of an appeal to authority.

Answer Choice (C) says the engineer hired by the company that maintains the bridge has examined the bridge and declared it safe. The engineer is a relevant expert who has examined the bridge and declared it safe. While we should be wary of subject matter similarity since LSAT writers like to use that as a trap, so far, (C) is analogous to the stimulus.

But (C) then says that the engineer is the only one to have checked the bridge. This idea is not present in the stimulus. In addition, the disagreement component is missing in (C) too. There is no analogue to the newspaper reporter.

Answer Choice (D) says the reporter who recently interviewed the prime minister said that the prime minister appeared to be in poor health. The paper has opposition leanings, so that is a bias. (D) is already diverging from the stimulus.

If we were to keep the subject matter of (D) but apply the reasoning in the stimulus, we would have to say that the reporter did a careful, thorough check (ideally, we’d change the reporter to a doctor to create the appeal to authority). And since the reporter is from an unbiased newspaper, we should be suspicious of, for example, the prime minister's press secretary, who claims that the prime minister is in good health. The edits above would make (D) better, but (D) does not resemble the stimulus in its current form.

Answer Choice (E) says the snowblower salesperson claims that there will be above-average snowfall this winter, but because the salesperson is biased, we can discount the claim. Since the salesperson is biased, (E) is already ruled out.

If we were to keep the subject matter of (E) but apply the reasoning in the stimulus as we did for (D), we would have to say that the snowblower salesperson recently and thoroughly inspected my snowblower and said that it was in good condition. The salesperson is not biased. Therefore, I should be suspicious of my neighbor's claim that my snowblower is in poor condition. You wouldn’t have the snowblower salesperson offer his opinion on the weather since that’s not within his domain of expertise.

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This is a Flaw/Descriptive Weakening question.

The stimulus says that if the proposed air pollution measures were to be implemented, ozone levels in the city's air would be one fifth lower, i.e., 20% lower, than current levels. Since the ozone in our air is currently responsible for $5 billion in health costs (premise), we would spend about a billion dollars less on these ozone-related health costs should the proposal be adopted (conclusion).

We always have two options when approaching Flaw questions. Either we identify the flaw in advance and go hunting for it in the answer choices, or use process of elimination. If you think this argument makes sense, keep an open mind as you go through the answer choices because the correct answer will point out something that you had not considered.

Answer Choice (A) says the argument fails to consider the possibility that other types of pollution not involving ozone might rise, perhaps even producing an overall increase in health costs. Sure, maybe particulate matter pollution or carbon dioxide pollution will rise. But the argument is completely contained to ozone and does not contemplate non-ozone-related health costs. So to criticize it for failure to do that is not a criticism of the logic of the argument.

(A) might be a fair criticism if we were having a discussion about health costs in general. But when we evaluate arguments in Weakening or Flaw/Descriptive Weakening, we have to limit that evaluation to the actual premise and conclusion presented, all of which are limited to ozone here. If (A) flies, then I can also say that the biggest contributor to health costs is heart diseases, not ozone, so we should talk about heart diseases if we really want to reduce health costs.

Correct Answer Choice (B) says the argument presumes, without providing evidence, that ozone-related health costs in the city vary roughly in proportion to ozone levels. This means if you reduce ozone levels by 20%, health costs would also go down by 20%. At a minimum, you should recognize that that is an accurate description of the assumption made. The argument is in fact presuming this, so (B) passes step one of the two-step test.

Now ask yourself if it is in fact reasonable to assume this. It turns out it is not. Ozone levels could generate health costs once the level of ozone passes a certain threshold. So it could be that ozone pollution is negligible until after a critical mass of the pollution has been accumulated, after which it becomes very damaging. If that were the case, then the 20% reduction might bring ozone levels under the threshold, which would result in health benefits of $5 billion. The opposite could also be true. Ozone levels could still be above the threshold even after the reduction, in which case we might not reduce health costs at all.

I am not saying this is how ozone levels actually work, but the point is that because we do not know how they work, we cannot make the naive assumption that the relationship between ozone levels and health care costs is proportional. There are so many other non-proportional relationships. And finally, in reality, the economic concept of diminishing marginal returns cuts against the assumption of proportionality.

Answer Choice (C) says the argument provides no explicit reason for believing that the proposed air pollution measures will in fact be adopted. Like (B), (C) is descriptively accurate. We do not know if the measures will be adopted or not. However, this is not the flaw. The premise says, “if the proposed air pollution measures were to be implemented,” so it is contemplating a hypothetical world. If we adopt it, what would happen?

Answer Choice (D) says the argument attempts to support the conclusion by making an appeal to emotions. The conclusion is supported by an appeal to math, not emotions. We think we would reduce health costs by 20% because the ozone levels will go down by 20%. An argument that did appeal to emotions would say something like “we should adopt the new ozone control measures because Timmy lost his mother to ozone pollution.”

Answer Choice (E) says the argument discusses air pollution to draw attention away from more significant sources of health-related costs. An argument actually guilty of this vulnerability would establish that a more significant source of health cost was, for example, heart disease. And the author would say, have you guys considered air pollution? There is ozone, nitrogen, volatile organic compounds, etc. That is trying to draw attention away from heart disease, which does not happen here.

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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.

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