Test: Logical Flaw - GMAT MCQ

This stimulus introduces a letter to the editor complaining of the reasoning in a recent article on
speed limits. In that article, it was noted that areas with lower speed limits had lower vehicle fatality
rates. But the letter writer concludes that it will not be that way for long, based on the fact that
vehicle-related fatalities are increasing in areas with lower speed limits.

The question stem asks why the reasoning in the letter writer’s argument is flawed. Whenever we
see simple numbers comparisons, we should be wary of the author’s tendency to draw unwarranted
conclusions. The problem here is that a simple increase in the number of vehicle related fatalities
does not provide sufficient evidence to logically draw any conclusions about whether these fatalities
are attributable to the lower speed limits. If we are seeking to determine whether or not safety is
increased by lower speed limits, a more relevant comparison would be between the respective
fatalities of high vs. low speed limit areas.

(A): Reliance upon empirical evidence cited in the original article is not a fl aw in the letter writer’s argument—it is quite common on the LSAT to see two different viewpoints or interpretations based on the exact same evidence. The author of the letter is not refuting the evidence provided by the original report, but rather the interpretation of that evidence, so this answer choice is incorrect.

(B): The term “often” is extremely vague, and provides no insight into the relative likelihood of fatalities at high speeds vs. low speeds. The reason the conclusion in the stimulus is fl awed is that it rests on a shaky premise, not that it fails to consider all outside evidence. This answer choice does not provide an effective attack on the stimulus’ reasoning.

(C): The fact that some drivers don’t want to drive any faster plays no role in the editorialist’s argument, since an increased speed limit would not require anyone to drive faster. The fact that some don’t wish to drive faster is irrelevant, and certainly does not represent a fl aw in the author’s reasoning, so this answer choice should be eliminated.

(D): This is the correct answer choice. If vehicle fatality rates are increasing everywhere, not just in the low speed limit areas, then we cannot logically draw any justifiable conclusions about the increase in fatality rates that has taken place in the low speed limit areas, and raising the speed limit based on these figures would not necessarily be advisable.

(E): The letter writer does provide some evidence (though questionable) against the
opposing viewpoint—the evidence that the vehicle fatality rate is increasing in the low speed limit
areas. This evidence may be weak, but the claim is presented, so this answer choice is inaccurate and
incorrect.

The journalist's argument is based on the results of a survey that found people who formulated new personal goals after personal catastrophes achieved readjustment more effectively and quickly than those who did not. The conclusion drawn is that counselors should primarily focus on encouraging their clients to formulate new personal goals for the most quick and effective readjustment.

Now let's examine each answer choice and see which one accurately describes a flaw in the journalist's reasoning:

(A) The journalist relies on the use of emotively colored language, rather than on the presentation of data. This answer choice does not describe a flaw in the journalist's reasoning. While it may critique the journalist's writing style, it does not point out a specific flaw in the argument itself.

(B) The argument fails to consider that the readjustment even of those who have not experienced personal catastrophes might be expedited by the formulation of new personal goals. This answer choice suggests that the argument fails to consider the potential benefits of formulating new personal goals for individuals who have not experienced personal catastrophes. However, this is not a flaw in the journalist's reasoning because the argument is specifically focused on people who have experienced personal catastrophes, as stated in the premises.

(C) The argument fails to consider whether, for those who have experienced personal catastrophes in their lives, maintaining previous personal goals might be beneficial for readjustment. This answer choice suggests that the argument fails to consider the potential benefits of maintaining previous personal goals for individuals who have experienced personal catastrophes. However, this is not a flaw in the journalist's reasoning because the argument is specifically focused on the effectiveness of formulating new personal goals for readjustment.

(D) The journalist’s generalization about what counselors should do relies on a study that, in its collection of data, did not include a sample of counselors. This answer choice points out a flaw in the journalist's reasoning. The journalist's conclusion about what counselors should do is based on a study that surveyed people who had experienced personal catastrophes but did not include a sample of counselors. Therefore, the journalist's generalization about counselor behavior may not be supported by the study's data.

(E) The argument fails to consider the possibility that the formation of new personal goals is an early stage of readjustment rather than its cause. This answer choice accurately describes a flaw in the journalist's reasoning. The argument assumes that formulating new personal goals is the cause of effective and quick readjustment, without considering the possibility that it may be an early stage or an indicator of readjustment. This undermines the journalist's conclusion about counselors focusing mainly on encouraging clients to formulate new personal goals.

Therefore, the correct answer is (E) because it accurately describes a flaw in the journalist's reasoning.

(A) presents one possible solution to a problem as the only solution to that problem: This answer choice is not relevant to the flaw in the argument's reasoning. The argument doesn't claim that paying full price for water is the only solution to the problem; it simply suggests it as a solution.

(B) bases its conclusion on an ambiguous interpretation of the word "inefficient": The argument doesn't rely on an ambiguous interpretation of the word "inefficient." It assumes that industries are wasting valuable water, and the conclusion is that if they have to pay full price for it, inefficient use of water would stop. The interpretation of "inefficient" is not the issue here.

(C) draws a conclusion that is stronger than what is warranted by the evidence presented: This is the correct answer. The evidence presented is that industries waste valuable water and that they currently pay little or nothing for it due to government subsidies. The conclusion that inefficient use of water by industry would soon cease altogether if they had to pay full price is a stronger claim than what is supported by the evidence. The argument doesn't provide sufficient evidence to support the claim that requiring industries to pay full price would completely eliminate inefficient water use.

(D) assumes what it sets out to prove: The argument doesn't assume what it sets out to prove. It proposes a solution (paying full price for water) to address the problem of inefficient water use by industries.

(E) offers as evidence considerations that have no relevance to the argument's conclusion: The argument does not offer irrelevant considerations as evidence. It presents the fact that industries waste valuable water and pay little or nothing for it, which is relevant to the conclusion that requiring them to pay full price would eliminate inefficient water use.

In summary, the flaw in the argument's reasoning is that it draws a conclusion (complete cessation of inefficient water use) that is stronger than what is warranted by the evidence presented. Therefore, the correct answer is (C).

The conclusion of the argument is that "people must not be as interested in buying new homes as they were even six months ago." Why? Because of several factors (developers not buying land, contractors without work, banks issuing fewer mortgages) that the author assumes result from the supposed lack of interest in buying new homes. Choice A suggests, though, that there may be an alternative explanation for all of those factors: interest rates are too high for most people. So even though they remain interested in buying homes, they simply cannot afford to do so and the whole housing market has slumped accordingly.

Conclusion: Irradiated food is not safe for human consumption. The author uses the fact that the studies were flawed to conclude that irradiated food is not safe for human consumption. Is this a reasonable conclusion? No. The studies purported to prove that irradiated food is safe. The fact that the studies used flawed methodology should have been used to prove that the studies did not prove that irradiated food was safe. Instead, the activist takes the argument too far, believing that because the studies did not prove that irradiated food is safe, therefore irradiated food is not safe. Here “Some evidence against a position is taken to prove that position is false.” Answer choice (A) perfectly describes this mistake.

Answer choice (B): Use the Fact Test to easily eliminate this answer. Although past studies were shown to have methodological flaws, this evidence is not used to prove that methodologically sound alternatives are impossible to achieve.

Answer choice (C): It’s true, the argument does fail to consider the possibility that a non-flawed study might provide only weak support for its conclusion. But—and this is the critical question—is that a flaw in the reasoning of the activist? No, it is perfectly acceptable for the author to ignore an issue (non-flawed studies) that does not relate to his argument. Remember, the correct answer choice must describe a flaw in the reasoning of the argument, not just something that occurred in the argument.

Answer choice (D): As with answer choice (C), the author has failed to consider the statement in this answer choice. But is this a flaw? No. The fact that animal testing is widely done and the results are accepted as indicative of possible problems with humans falls under the “commonsense information” discussed back in Chapter Two. Testing products on animals is a current fact of life, and the author made a reasoning error by failing to consider the possibility that what is safe for animals might not always be safe for human beings. Another way of looking at this answer is that it effectively states that the author has failed to consider that there is a False Analogy between animals and humans. He fails to consider it because the analogy between animals and humans is not false.

Answer choice (E): Again, the activist does fail to establish this, but it is not necessary since the independent scientists only commented on the methodology of the study, not the irradiated food itself.

The argument states that a certain airport security scanner alerts the operator whenever there is an explosive in the luggage. However, the scanner also erroneously alerts the operator for 1% of the luggage that contains no explosives. The argument concludes that in 99 out of 100 alerts, explosives will actually be present.

(A) This answer choice brings up the possibility that the scanner might fail to detect explosives when they are present. However, this is not directly relevant to the flaw in the given argument, which deals with the occurrence of false positives.

(B) This answer choice suggests that the argument's conclusion is based on a biased sample. However, there is no mention of a sample being used in the argument, so this is not the flaw being targeted.

(C) This answer choice raises the possibility of human error on the part of the scanner's operator after an alert is signaled. However, this is outside the scope of the argument, which focuses on the accuracy of the scanner itself.

(D) This answer choice introduces the idea that the scanner might not be equally sensitive to all types of explosives. While this is a valid concern, it does not directly address the flaw in the argument, which is about the occurrence of false positives.

(E) This answer choice correctly identifies the flaw in the argument. The argument incorrectly substitutes one group (luggage containing no explosives) for a different group (alerts made by the scanner). The argument assumes that 99% accuracy in alerts automatically corresponds to 99% of alerts having explosives present. However, this ignores the possibility of false positives, where the scanner erroneously alerts the operator for luggage containing no explosives.

Therefore, the correct answer is (E) because it accurately identifies the flaw in the argument.

(A) Never ask all respondents a question if it cannot reasonably be answered by respondents who make a particular response to another question in the same survey. In the given survey, all respondents were asked two questions about each brand: recognition and approval. The violation of this principle is not evident based on the information provided. It does not specify that respondents were unable to answer one question based on their response to the other question. Therefore, it is not clear how this principle is violated.

(B) Never ask a question that is likely to generate a large variety of responses that are difficult to group into a manageable number of categories. The survey asked respondents about recognition and approval for each brand. The results showed that the recognition and approval rankings often differed sharply. This indicates that the responses generated a large variety of opinions, making it difficult to group them into manageable categories. Therefore, this principle is violated.

(C) Never ask all respondents a question that respondents cannot answer without giving up their anonymity. The survey did not mention any questions that would require respondents to give up their anonymity. The principle of anonymity is not applicable to the violation of this survey.

(D) It is better to ask the same question about ten different products than to ask ten different questions about a single product. The survey asked two different questions about each brand: recognition and approval. This violates the principle of asking the same question about different products instead of multiple questions about a single product. Therefore, this principle is violated.

(E) It is best to ask questions that a respondent can answer without fear of having gotten the answer wrong. The survey did not provide any indication that respondents were afraid of getting the answer wrong. This principle does not seem to be violated based on the information given.

Based on the analysis, options (B) and (D) are violated by the survey. However, only option (A) is provided as the correct answer. It is possible that the survey violates multiple principles, but based on the given options, (A) is the best choice among the provided options.

Argument: Recent research suggests that training programs emphasizing flexibility, such as yoga and pilates, are more effective at preventing injuries in athletes than programs focusing solely on strength and speed. Bournemouth Football Club had fewer injuries than Haleford Football Club in the past season. Therefore, it can be concluded that Bournemouth's training program included more flexibility activities than Haleford's program.

(A) Generalizes from too few data points: This option suggests that the argument is vulnerable because it draws a conclusion based on insufficient evidence. However, the argument compares the injury rates of two specific football clubs, so it does not necessarily generalize to all training programs. Therefore, this option is not the most vulnerable criticism.

(B) Uses its own conclusion as one of its major premises: This option suggests that the argument's conclusion is used as one of its premises. However, the argument does not rely on its own conclusion as a premise. It uses recent research to support the claim that flexibility training is more effective at preventing injuries. Therefore, this option is not the most vulnerable criticism.

(C) Assumes that the consequence of one set of circumstances would not be produced by another: This option points out that the argument assumes the training program's effectiveness based on the injury rates of the two football clubs. However, there could be other factors influencing the injury rates, such as differences in playing style, field conditions, or player behavior. Therefore, this option is the most vulnerable criticism because it questions the assumption that the difference in injury rates can be solely attributed to the training programs.

(D) Fails to consult alternative research studies: This option suggests that the argument is vulnerable because it does not consider alternative research studies. While the argument does not explicitly mention consulting other studies, it does mention recent research supporting the effectiveness of flexibility training. Therefore, the argument is not necessarily vulnerable to this criticism.

(E) Does not distinguish between incidence of injury and degree of injury: This option suggests that the argument fails to consider the difference between the frequency of injuries (incidence) and the severity of injuries (degree). However, the argument does not discuss the severity of injuries and focuses solely on the number of injuries. Therefore, this option is not the most vulnerable criticism.

In conclusion, option (C) is the most vulnerable criticism because it questions the assumption that the difference in injury rates can be solely attributed to the training programs, without considering other factors that could have influenced the outcomes.

Now let's examine each answer choice:

(A) It dismisses a claim because of its source rather than because of its content. This answer choice is not applicable to Deirdre's argument. Deirdre does not dismiss any claims based on their source; instead, she challenges the content of the philosophers' claims.

(B) It fails to take into account that what brings someone happiness at one moment may not bring that person happiness at another time. This answer choice is not the reasoning flaw in Deirdre's argument. Deirdre's argument does not address the issue of changing preferences or circumstances; she simply asserts that walking along the seashore brings happiness without considering possible variations over time

(C) It allows the key term "happiness" to shift in meaning illicitly in the course of the argument. This answer choice correctly identifies the reasoning flaw in Deirdre's argument. Deirdre starts by discussing happiness as the satisfaction derived from fully living up to one's potential, as claimed by philosophers. However, she then shifts the meaning of happiness to a more immediate and fleeting feeling that can be experienced by walking along the seashore. This inconsistency in the meaning of "happiness" undermines the coherence of her argument.

(D) It presumes, without providing justification, that happiness is, in fact, the goal of life. This answer choice is not the reasoning flaw in Deirdre's argument. Although Deirdre assumes that happiness is the goal of life, this assumption is not the central flaw in her reasoning.

(E) It makes a generalization based on the testimony of a group whose views have not been shown to be representative. This answer choice is not the reasoning flaw in Deirdre's argument. Deirdre does not rely on the testimony of a specific group to make her argument; instead, she asserts that walking along the seashore causes many people to experience happiness without specifying the source of this information.

In summary, the correct answer is (C) because Deirdre's argument allows the key term "happiness" to shift in meaning illicitly, undermining the coherence of her argument.

Raphaela's Argument:

• Forcing people to help others is morally wrong.
• Therefore, no government has the right to redistribute resources via taxation.
• Anyone who wants can help others voluntarily.

Edward's Argument:

• Governments do have the right to redistribute resources via taxation.
• Insofar as they give people the freedom to leave and hence not to live under their authority.

The disagreement between Raphaela and Edward revolves around the morality and rights of governments to redistribute resources via taxation.

Now let's analyze each option:

(A) Any government that does not permit emigration would be morally wrong to redistribute resources via taxation. This option aligns with Edward's argument, as he emphasizes the importance of allowing people to leave if they don't want to live under a government's authority. Raphaela's viewpoint on emigration is not explicitly stated, so it's unclear if she agrees or disagrees with this option.

(B) Any government that permits emigration has the right to redistribute resources via taxation. This option captures the essence of Edward's argument, as he believes that as long as governments allow people to leave, they have the right to redistribute resources via taxation. Raphaela's stance on emigration is not specified, so she may or may not agree with this option.

(C) Every government should allow people to help others voluntarily. While Raphaela argues in favor of voluntary help, it is not clear if Edward supports or disagrees with this option. His focus is on the rights of governments and the freedom to leave their authority, not necessarily on whether every government should allow voluntary help.

(D) Any government that redistributes resources via taxation forces people to help others. Both Raphaela and Edward would likely agree with this statement. Raphaela argues that forcing people to help others is morally wrong, which implies that government redistribution via taxation involves forcing. Edward's viewpoint is not explicitly stated, but his argument suggests that he believes governments have the right to redistribute resources, even if it involves forcing people to contribute.

(E) Any government that forces people to help others should permit emigration. This option aligns with Edward's argument, as he emphasizes that governments should allow people to leave if they don't want to live under their authority. Raphaela's position on this specific point is not explicitly stated.

Given the analysis above, the disagreement between Raphaela and Edward is best captured by option (B): Any government that permits emigration has the right to redistribute resources via taxation.