Here we have a flaw question, which we know from the question stem: “Which of the following describes an error of reasoning in the merchants’ argument?” Right away we know our correct answer has to do two things: be descriptively accurate, and describe the flaw of the stimulus. We also know what the wrong answers will do - describe reasoning flaws we’ve seen before, but don’t like up with our stimulus. Once we have a clear understanding of the questrion’s objective, we can proceed into structural analysis of the stimulus.
Our argument begins with a proposed law restricting outdoor advertising abilities in Penglai to small signs of a standard shape identifying a place of business. Next, we are introduced to the opposition. We learn some island merchants are protesting the proposed law because the overall amount of business being brought in would be reduced. The protestors’ base their reasoning on a government study where businesses with outdoor advertising tended to have a bigger market share than those who did not use outdoor advertising.
Ultimately, our speaker is concluding causation from correlation. Simply on the basis that business with outdoor advertising happened to have more business the speaker concludes the increased business is because of the use of outdoor advertising. Remember that our conclusion is something that has to be true on the basis of our premises. Just because these businesses have two qualities at the same time does not mean we can assume a causal relationship. It could be the case that a third outside factor impacts both business volume and outdoor advertising trends in the exact same way.
Knowing that our speaker incorrectly presumes causation from a correlation, we can proceed into answer choice elimination.
Answer Choice (A) This is not descriptively accurate. Our argument does not claim there are simply no reasons to enact the law. Instead, our argument claims that there is a bad impact that would follow from the enactment of the law.
Correct Answer Choice (B) This is exactly what we are looking for. This descriptively accurate answer choice is the only option that points out the existence of a third factor explaining the results in the government’s study. Answer choice B explains that businesses were more successful using outdoor advertising not because it raises the level of overall business available, but simply because it allows businesses to poach customers from their competitors. This points out the strength of the argument’s conclusion. Our speaker did not conclude that businesses with outdoor advertising were generating more business - instead, they were stealing business from their competitors.
Answer Choice (C) This answer is descriptively accurate, but not the ultimate issue in our stimulus. Whether or not the study is objective (100% factual without subjectivity) does not change the fact that our author incorrectly interpreted the meaning of the study.
Answer Choice (D) Here, we have another answer choice that is technically correct in description but does not identify the true issue with our argument. By telling us that the argument fails to establish that market share was exactly proportional to advertising, this answer choice does not attack the causal mistake seen in the argument.
Answer Choice (E) This brings us to our last descriptively correct answer choice that fails to describe the true issue of our stimulus. The consideration of this law being “constitutional” does not connect to any sort of the reasoning presented in the stimulus. Knowing our correct answer choice will highlight the flaw with the author’s interpretation of the study, we can eliminate this answer.
We know this is a strengthening question because of the question stem: Which one of the following, if true, most strongly supports the conclusion regarding a signaling function?
The first sentence gives us two facts about zebras and their stripes; all zebras have stripes, and the most widespread subspecies of zebra has the best defined stripes. A sub-conclusion is drawn from these facts that the stripes must have some kind of importance for zebras. Whenever you see a sentence that takes the form of “Since X, Y.” you should expect that you are being given a final premise followed by a conclusion. That’s exactly what we get, and from the final premise that the zebra stripes aren’t good for camouflage, the author concludes they must act a some kind of signal for other zebras. This is the signaling function conclusion we were told about in the question stem.
An important detail to note is that it is a signal for specifically other zebras. A good way to filter out wrong answers will be whether the explanation they offer involves three elements; (1) stripes, (2) signaling, and (3) an effect on other zebras. Let’s look at the answer choices:
Answer Choice (A) This answer gives us a correlation between defined stripes, and size and vigor. Always remember to anchor yourself in the conclusion on strengthening questions; we want to support a connection between stripes and a signaling function. This answer is irrelevant to that conclusion. A is incorrect
Answer Choice (B) If having stripes can make zebras harder to spot under certain conditions, that suggests that they do function as camouflage. This contradicts what we’ve been told in the stimulus, and by introducing an alternate hypothesis to our signaling function directly weakens what we want to support. B is incorrect.
Answer Choice (C) While this answer does pick up on the signaling function part of the conclusion, it has nothing to do with zebra’s and their stripes. We’ve been given no information that suggests zebra’s can temporarily change their color. C is incorrect.
Correct Answer Choice (D) Our conclusion is that the stripes must serve as some kind of signal for other zebras. This answer gives us an explanation of how the stripes could serve this function; Zebras react faster to shapes with stripes, so Zebras having stripes allows them to react to each other’s movement more quickly. This is the only answer with all three elements we mentioned. D is correct.
Answer Choice (E) Like C this answer might appeal in the moment because it mentions signaling, but it is important to stay anchored in our conclusion. We want support for the stripes acting as a signal, and therefore other potential signals Zebras might have are not helpful. E is incorrect.
Here we have a strengthening question, as the stem asks: Which one of the following, if true, would most support the naturalists’ prediction?
The stimulus begins with an opinion of some scientists; they believe mice must depend on human civilization for their continued existence. They support this conclusion with the claim that the relationship between mice and humans has diminished their ability to survive in nature. The author quickly makes their position clear and states that the scientists opinion ignores significant facts. While this is the author’s conclusion, it’s important to remember that our job is to specifically support the naturalists’ prediction.
To support his dismissal of the scientists opinion, the author cites several facts. First, Mice have managed to be the most widely distributed mammal after humans, despite threats from predators and humans. Second, they reproduce rapidly. Third, and more important to their survival than rapid reproduction, Mice can adapt to lots of different environments. To further bolster his case, the author quotes a prediction made by naturalists that mice would continue to survive even if the environment became too extreme to support humans.
This question is a good example of why it is important to read a question stem carefully. In this stimulus we are given three positions from three different groups: (1) the scientists’ argument that mice depend on humans, (2) the author’s argument that they don’t, and (3) the naturalists prediction that mice can survive extreme environments. The position we want to strengthen only takes up one sentence of this long stimulus! If we didn’t read the question stem carefully, we might misjudge answer choices based on how they affect the author or the scientists’ conclusion. Always read the question stem carefully.
The correct answer is the one which most strengthens the prediction that if the environment became too extreme for human life, then mice would be able to adapt and survive. Let’s take a look at the answer choices:
Answer Choice (A) We want to strengthen the prediction that mice will survive even if the environment is too extreme for human life. This, if anything, weakens that prediction by introducing a limiting factor on mouse survival. A is incorrect.
Answer Choice (B) The stimulus has already told us that mice reproduce rapidly, so this answer doesn’t add anything new as support. Even, worse it only tells us something about mice under optimum conditions. The prediction we want to strengthen concerns what would happen to mice in an extreme environment. It is safe to assume that an extreme environment is not optimum conditions. B is incorrect.
Answer Choice (C) This answer relies on conflating the ability of mice to adapt and survive if the environment becomes too extreme for humans with the ability to survive an environment without humans. This answer might seem appealing if you failed to read the question stem carefully and believe our job is to strengthen the author’s position. However, this information is irrelevant to the naturalist’s extreme environment prediction because nothing we are told indicates that pre-colonial America was an extreme environment. C is incorrect.
Correct Answer Choice (D) This answer gives us a case where mice did exactly what the naturalists predict they can do; they encountered an environment too extreme for human life, and were able to survive. Think of it as an experiment testing their hypothesis. An experiment whose results correspond to a general prediction will always, all else being equal, strengthen that prediction. D is correct.
Answer Choice (E) This information supports the scientists point about the dependence of mice on human civilization, but that isn’t what we’ve been asked to strengthen. For our naturalists prediction it adds no support. E is incorrect.
Here we have a flaw question, which we know from the question stem: “The reasoning in the argument is flawed because the argument…” Right away we know our correct answer has to do two things: be descriptively accurate, and describe the flaw of the stimulus. We also know what the wrong answers will do - describe reasoning flaws we’ve seen before, but don’t like up with our stimulus. Once we have a clear understanding of the questrion’s objective, we can proceed into structural analysis of the stimulus.
The stimulus begins with a fact; the new proposed cut to arts funding will make things difficult for arts organizations. Despite this, the author concludes the funding cut will not put these groups entirely out of existence. The stimulus ends with the main reasoning for the author’s conclusion, that we know these groups will continue to exist simply because they survived a budget cut in the past.
Our conclusion definitely does not follow from our premises here. Just because the group survived a budget cut in the past, that has no bearing on whether the groups will survive after this next cut. If anything, the groups seem even less likely to survive if they face one budget cut after surviving another budget cut in the previous year alone.
Knowing that our speaker incorrectly presumes because the arts survived one past cut they must survive this newly proposed budget reduction, we can proceed into answer choice elimination.
Answer Choice (A) This answer choice is not descriptively accurate. Without seeing somewhere in the stimulus where the speaker claims that the economy is without a doubt going to improve, we can eliminate this answer choice from consideration.
Answer Choice (B) Answer choice B is descriptively accurate, but not the ultimate issue with our argument. The justification of the existence of the arts group is not in question. Instead, our speaker focuses on whether or not they will be able to exist moving forward past this new proposed funding cut.
Answer Choice (C) This is not what we are looking for. Answer choice C goes beyond what our stimulus concludes by saying the speaker equated surviving with thriving. But nowhere does our speaker tell us the arts are thriving. For all we know, they exist at a 10th of the capacity as they did before the funding cuts. Our stimulus is concerned with the group existing at all - not whether that existence is a good one.
Answer Choice (D) The amount of our budget cuts is not the issue with our stimulus. Although this answer choice is descriptively accurate in that our speaker does not take this into account, our correct answer has to also hit on the exact reason why the speaker is flawed. The problem with our stimulus centers on a past/future assumption rather than the exact amount of those proposed cuts.
Correct Answer Choice (E) This is exactly what we are looking for. This descriptively correct answer choice points out the right issue in our stimulus by telling us that our speaker does not consider the already weakened position of the arts’ group. If the group survived one budget cut, they could very well be put entirely out of business by another round. The cumulative effect of those multiple budget cuts lines up well with our identification of the flaw in the stimulus.
This is a necessary assumption question; we know this because the question stem says: “… following assumption on which the consumer activist’s argument depends?”
Necessary assumption questions fall under the umbrella of the strengthening subset of questions. The analysis of the stimulus is the same. However, our approach changes with our answer choices. Where we were trying to find an answer choice that justified our argument in strengthen, pseudo-sufficient/sufficient assumption questions, the purpose of a necessary assumption correct answer choice is very different. We’re trying to find what is necessary for our argument. In other words, in order for our conclusion to be true/for our argument to work, the correct answer choice must be true.
On the old LSAT, the test would give us one stimulus for 2 questions. Unfortunately, that is no longer the case – the LSAT will definitely give us 25-26 different stimuli for us to get this. Question 17 was a NA question that required us to read both blurbs. For this question, we can ignore the “industry representative” blurb.
The activist’s claim is a single sentence. There is a lot of information packed in here, so let’s break this up by commas starting by reading up until the third comma. We know that airlines were allowed to (and did) abandon all of the routes except their most profitable routes. By whom were they allowed to do this? We don’t know yet.
If we read on, we’re told that the “government’s decision to cease regulation…” What decision are they referring to? Well, it must be their decision to let airlines choose their routes. We’re told that this decision has worked to disadvantage everyone who can’t get to major airports, presumably because this is where all of the “profitable” routes go through.
The first half of the sentence provides support for the second half. The premise is that because the government allowed airlines to abandon whatever routes, the government’s decision hurt certain people. This seems fine at a surface level, but there is a very subtle gap here. There is a correlative-causal element. The argument correlates the timing of the government’s decision to the timing of airlines abandoning routes, and then assigning blame to the governments for the airlines’ actions in the conclusion. Because of the government’s decision, people are disadvantaged. Remember, in the core curriculum correlation does not imply causation (lesson linked here). The airlines could have just decided to do whatever they wanted, regardless of what the government said.
There could be many necessary assumptions for this argument. In order for the causal conclusion to be true, one necessary assumption is affirming that the causal connection exists.
Answer Choice (A) While the argument does talk about advantages in the conclusion, whether or not there was an advantage of easy access before the decision is not necessary for the conclusion or the argument. A change in the ease of access to large metropolitan airports is not necessary for the argument either. This is out.
Answer Choice (B) A change should be reversed? Our conclusion does not hinge on a prescriptive statement. This is not necessary for our conclusion to be true.
Answer Choice (C) Must this answer choice be true in order for our conclusion to be true? No! “Almost always” could be changed to “rarely” and our argument would still stand. This isn’t necessary.
Correct Answer Choice (D) This addresses the correlation-causal element we discussed above and affirmed a partial causal relationship. If we negate this relationship (instead of “at least in part” we get “no part”) this would destroy the argument.
Answer Choice (E) This is not necessary for the conclusion to be true. Regional airlines could have excellent customer service without the reach/routes of major airlines.
This is a necessary assumption question because the stem tells us that the argument “depends on the assumption.”
Necessary assumption questions fall under the subset of strengthen questions. All of the things we learned for strengthen, SA, and PSA question are still very important here! We’re going to be analyzing the stimulus the same way: identify the premise and conclusion, evaluate the argument, and determine what is missing. Our approach to the questions is very different. For NA question, in order for our conclusion to be true, our correct answer must be true. Without the correct answer, our argument will fall apart. This is what we’re looking for in our answer choice. Remember, we can always test our answer choices by using the negation test: if we negate the answer choice and it destroys our argument, it is the correct answer!
The first sentence is pretty straight-forward: the permits are issued in terms of pounds of each chemicals that can be dumped into the waterway per day. So, each chemical has a specified weight that can be dumped in the water each day. We’re also told how these numbers are calculated: by looking at the effects dilution in the water based on the amount of water flowing through the waterway. So there’s two variables here: the dilution and how much water passes through the waterway. This makes sense: if you have more/less water flowing through the waterway, dilution will change. Great! The next sentence is the conclusion: based on all of this information, the waterway is protected.
On the LSAT, there is a correct amount of skepticism you need to have. The argument is okay but, while it’s difficult to pinpoint, there is a gap here. A number of things could happen in order for this conclusion to not be true. For example, what if no one follows these guidelines? What if calculation of water flowing through the waterway isn’t accurate because the flow of water changes through the day? Any number of things need to be true if our conclusion, the waterway is protected, is true.
Correct Answer Choice (A) This is necessary for the argument! If, even in safe quantities, chemicals interact to form harmful ones, that would destroy our argument.
Answer Choice (B) Is rapid dispersion necessary? Maybe the flow is very slow, but the amount of chemicals allowed in the waterway is very low. This is not good.
Answer Choice (C) This is also not necessary. Let’s take the negation of this sentence: some chemicals are prohibited from being discharged into the waterway. So, what? Perhaps arsenic isn’t not allowed to be dumped - is that compatible with the argument? Yes! Prohibiting certain chemicals to be dumped in the waterway does not destroy the argument.
Answer Choice (D) This is also not necessary. The permits indicate the max amount that can be dumped into the water, which means dumping anything at the maximum amount or below is fine. Negating this sentence (they dump the full amount indicated by the permit) does not destroy the argument.
Answer Choice (E) This weakens our argument a little bit - it mentions what we’re not taking into consideration in an effort to say that the waterway may not be as protected as the argument says. This is out.
This is a necessary assumption question because the stem tells us that the argument is “depends” of the which of the offered “assumption.”
Necessary assumption questions fall under the subset of strengthen questions. All of the things we learned for strengthen, SA, and PSA question are still very important here! We’re going to be analyzing the stimulus the same way: identify the premise and conclusion, evaluate the argument, determine what, if anything, is missing. Our approach to the questions is very different. For NA question, in order for our conclusion to be true, our correct answer must be true. Without the correct answer, our argument will fall apart. This is what we’re looking for in our answer choice. Remember, we can always test our answer choices by using the negation test: if we negate the answer choice and it destroys our argument, its the correct answer!
This first sentence gives us the definition for addiction and, interestingly, the author uses “has been defined as” which kind of gives us the sense that this may be other people’s definition. This definition is that addiction means the dependence on and abuse of a certain substance. If we read onto the next sentence, even if the “however” is at the end, we can infer that the author does not agree with the running definition of addiction; he says that abuse and dependence do occur together.
The next two sentences are examples of this. He says cancer patients are dependent on morphine, but do not abuse it because they use it for their pain. And then he gives a general example of the reverse: a person can abuse morphine but does not need to dependent on it for anything.
Then we see our conclusion, which we predicted above: this definition of addiction is not correct.
This argument is fine. The salient feature of difficult NA question is that the correct answer choice can be VERY subtle. The negation test will be helpful for these answer choices.
Answer Choice (A) This is not necessary to our argument. Cancer patients could have abused morphine is the past; the argument allows for this! The example in the argument is a hypothetical that can occur. And if we negate the answer choice (cancer patients sometimes abuse morphine), this is completely compatible with the argument because the example with the cancer patient is a hypothetical.
Answer Choice (B) This is not necessary for the argument. This answer choice is trying to draw a distinction between the hypothetical language of the argument and what will happen. However, it is not necessary for all cancer patients to often become dependent on morphine. Similar to what we said in AC (A), cancer patients rarely (instead of often) becoming dependent to morphine and the rest never becoming dependent is compatible with the argument.
Correct Answer Choice (C) When we read the argument, we just assumed that we were obviously talking about cancer patients who were addicted to morphine. But, we did not explicitly say that. If we negate this answer choice, it destroys our argument because the example we give to lend support to our argument becomes useless if the cancer patients are not addicted. In other words, if the individuals discussed in our examples are just dependent on or abusing a substance and not addicted, our argument falls apart. Very subtle!
Answer Choice (D) Similar to (A) and (B), this is not necessary for the argument. It could be the case that some cancer patients are just abusing the drug without being dependent on it. The negation of this doesn’t destroy our argument.
Answer Choice (E) This would weaken our argument; we’re trying to prove that abuse and dependence can happen separately while being addicted.
This is a necessary assumption question and the stem asks: the argument is based on which one of the following assumptions?
The first sentence asks as a concession to the opposing side: as subsidies go down, it’s obviously very hard to maintain the quality of service. In the next sentence, we see an important “pivoting” word: however. This sentence is saying that even though we have less money, the amount of passengers riding has gone up. The next sentence is the conclusion and the “this fact” at the beginning of the sentence refers to the sentence right before it about the number of riders increasing. The conclusion is that their quality of service has been satisfactory. So, even though they have less money, riders are still riding. From this much, doesn’t our conclusion seem like a bit of a stretch? For example, let’s pretend that the NYC subway system is getting less and less money every year. Do you think New Yorkers will ride the train because the quality of service is fine or because they may not have any other choice? The former could be true, but the latter is more likely to be true. Now, we’re not trying to weaken the argument, but this level of analysis is still very important.
Answer Choice (A) This answer choice is pointing out the wishes of taxpayers. The argument does not depend on what taxpayers wish. If we negate this, it doesn’t do anything to the argument.
Correct Answer Choice (B) This is conditional language - do you see the “some” and the “if”? This is a “some” conditional, so we can flip the NC and SC as we please, but let’s flip these two. If some people are dissatisfied with the service, they will not ride the train. Remember what our argument is: people are riding the subway regardless of the reduction in subsidy, therefore they must be satisfied. Does our argument depend on this? Absolutely. Let’s negate it to check: if some people were dissatisfied with the service, they would still take the train. That destroys our argument.
Answer Choice (C) This is an attractive answer choice, but is improvement necessary to the argument? No! The riders could be totally okay with the way the train is now, and that’s why they’re satisfied with the service.
Answer Choice (D) This answer choice is incorrect for similar reasons to the answer choice above. Is a decrease in quality of service necessary for satisfaction with the service? No! What if they’re still satisfied even if the quality of service went down just a little bit? That would not affect the argument at all.
Answer Choice (E) This answer choice is noting that even though the subsidy itself was decreased, the revenue will offset the reduction. Is this necessary for our argument that the passengers are satisfied? No! Would this be nice to have, sure; however, even if this didn’t happen, our argument would be intact.
This is a flaw/descriptive weakening question, and we know this because of the question stem: “…reasoning is most vulnerable to which one of the following criticisms?”
Let’s take a look at the first sentence. Despite his usually poor appetite, Monroe enjoys three meals at Tip-Top but becomes sick after each meal. Immediately, this sounds like a correlation: the phenomenon of becoming sick occurring with the phenomenon of eating a Tip-Top.
The second sentence is pretty straightforward: it’s a list of each meal he ate at the restaurant. Interestingly, they’re all very large meals, especially for someone who generally has a “poor appetite,” and they all have a side of hot peppers. Both of these look like premises. They’re both statements of facts.
What does our conclusion say? Since all three meals had peppers (premise), Monroe concludes that he became ill solely due to Tip-Top’s hot peppers. Solely? Not only is he assuming causation, but it’s very restrictive. Sure, hot peppers may have contributed to feeling ill, but what about eating this kind of unhealthy food? What about eating this amount of food? What if he’s lactose and fried-food intolerant? The causal relationship he establishes is shaky because “solely” is an unwarranted restriction in the implied causation.
Answer Choice (A) It’s hard to establish whether or not it’s descriptively accurate because “too few” is pretty subjective. We sometimes know after one meal why we got sick. Additionally, he still got sick after each of these three meals, so there must be some reason he’s getting sick. But let’s just say it is accurate. Is this the flaw? No! This isn’t a sample size issue; it’s the restriction in the causal relationships that’s an issue. It could be that hot peppers partially contributed to him feeling ill, in which case 3 meals isn’t “too few.”
Answer Choice (B) This is not correct because it’s descriptively inaccurate. We know explicitly from the stimulus that he became ill after consuming each the meal (read first sentence).
Answer Choice (C) This is not descriptively accurate because, although he may want to continue dining at Tip-Top, there is no evidence of this biasing his conclusion. Also, if he wanted to continue eating at Tip-Top, it would make more sense for him to blame his illness on something outside Tip-Top’s control/menu.
Answer Choice (D) This is descriptively accurate, but it’s not the flaw. Just because hot peppers didn’t make everyone else sick, that doesn’t mean it cannot make Monroe sick. Other people’s reaction to the hot peppers is not relevant to the conclusion Monroe draws, and even if this was established, it would not strengthen Monroe’s position.
Correct Answer Choice (E) It demonstrates that his causal relationship is unwarranted by introducing an alternative cause, which we know is one of three ways to disprove a causal relationship.