LSAT Logical Reasoning : LSAT Logical Reasoning
Study concepts, example questions & explanations for LSAT Logical Reasoning
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Example Questions
Example Question #191 : Lsat Logical Reasoning
Economist: Recessions are a natural part of any economy, as no advanced nation has ever experienced a significant length of time without slight bumps. The serious fretting over economic downturns is silly, as economic booms are right around the corner. Even if people lose some of their money, it should come back.
Politician: Any economic suffering a person has is something that should be avoided. Preventing even the smallest recessions is a priority that anyone with a responsibility for the economy must have.
The flaw in the economist’s argument would be stated by the politician as __________.
emphasizing the problems with a recession to an economy
overstating the need for economic action
underestimating the effect of a recession
creating a false sense of panic over economic recessions
misunderstanding why economic recessions happen
underestimating the effect of a recession
The politician does not directly criticize the economist, but rather presents a viewpoint about avoiding economic recessions because of the pain it could cause people. The economist's argument is that the effect of an economic recession is not that serious, which the politician would say is minimizing the effects of the recession.
Example Question #192 : Lsat Logical Reasoning
University Dean: These accusations of grade inflation at our university are untrue. A recent survey of our students proves that students are always graded fairly, because 93% of former students responding said that they had always been graded fairly in their courses here.
The flaw in the dean's argument is that it:
Generalizes based on a sample that might not be representative.
Does not define the word "fairly."
Justifies a claim based on unverifiable evidence.
Presents an initial claim that is true only if one assumes that the conclusion is true.
Assumes that grading methods were different for former students compared to grading methods for current students.
Generalizes based on a sample that might not be representative.
The dean uses a survey of former students about the fairness of grading processes to justify his argument that grades are not artificially inflated at his university. He does not provide any information about the sample size of the survey, uses former students rather than current students, and generalizes that the university's entire grading practices are "fair" based on this sample.
Example Question #28 : Flaw
The candidate with the most screen time in a televised debate usually receives the largest poll bump. As Mr. Smith received ten percent more screen time in the most recent debate, he should see a significant improvement in his poll numbers.
Which of the following statements best describes the flaw in the argument presented in the above passage?
That all politicians feature the same talking points in debates.
That the debate was focused on serious issues that voters most care about.
That an event which has occurred in the past is guaranteed to occur in the future.
That most politicians focus on winning debates as compared to the other aspects of campaigning.
That the use of poll numbers is always reflective of actual opinions and beliefs.
That an event which has occurred in the past is guaranteed to occur in the future.
The passage states that Mr. Smith will see a jump in his poll numbers, because he had the most screen time during a debate. The only evidence for this conclusion was that the candidates whose poll numbers had most improved were the ones who had gotten the most screen time in previous debates. This would be the biggest flaw in the statement. Also, just because the candidates saw the biggest relative improvement, does NOT mean that the leap to calling this potential bump in numbers as significant.
Example Question #31 : Flaw
Drivers often believe that a lane that is closed for roadwork is one to be avoided if the problem is to be passed more quickly. However, being in the lane which is merging often means cars are moving more and create motion which allows the lane to be faster overall. Additionally, the swarm of cars moving out of the lane and into others causes problems with the other lanes of traffic.
Which of the following best describes the flaw in the argument presented above?
The argument relies on an assumption that is not sufficiently supported.
The argument does not present a conclusion based on any evidence.
The argument is presented based on incomplete evidence.
The argument presents two very different pieces of evidence to support its conclusion.
The argument is based on an assumption that is denied in other parts of the statement.
The argument presents two very different pieces of evidence to support its conclusion.
The statement presents its conclusion in its opening statement, but then presents its reasons afterwards; however, the passage oddly makes two different statements that are not entirely congruent together, and even make somewhat conflicting arguments.
Example Question #32 : Flaw
Tad and Lilly play together in kindergarten every day. Both children have symptoms of an illness. Tad definitely does not have an illness. Lilly’s illness symptoms are similar to Tad’s symptoms. Since Tad does not have an illness, Lilly does not have an illness.
The reasoning in the argument is flawed because the argument:
Does not reason that one infection might be a different kind of illness.
Wrongly infers that, because something in one instance has not occurred, it has not occurred in a similar situation.
Argues that because something is probably true, it is true.
Makes a general claim where specific facts are needed.
Treats symptoms as facts.
Wrongly infers that, because something in one instance has not occurred, it has not occurred in a similar situation.
The flaw in the argument is that Tad’s situation and Lilly’s situation are the same simply because they play in kindergarten together every day. While the evidence that they play in kindergarten is compelling at first and may lead one to select one of the other false answers, it is flawed because it is not certain. The symptoms, even if similar, could be for something else. The question does not provide us with information concerning other illnesses which might have the same symptoms.
Example Question #33 : Flaw
Brianna: Laura claims that her phone battery dies too quickly because I dropped her phone on the floor. However, she also admitted that her phone battery died too quickly on many other occasions, despite never having been dropped on the floor on those occasions. Therefore, Laura is wrong in claiming that I caused her quickly dying battery by dropping the phone on the floor.
The reasoning in Brianna's argument is most flawed in that it:
Does not consider the possibility that dropping the phone caused the screen to crack.
Assumes that Laura is blaming her for dropping the phone.
Doesn't consider the possibility that dropping any phone would cause its battery to die quickly.
Fails to consider that even though the battery died quickly in the past without the phone having been dropped, dropping the phone could still be a cause of a quickly dying battery in this case.
Assumes that her claim is true without any evidence.
Fails to consider that even though the battery died quickly in the past without the phone having been dropped, dropping the phone could still be a cause of a quickly dying battery in this case.
Brianna states that her sister is mistaken about the cause of her battery dying quickly simply because it died quickly in the past because of a different cause. However, it is possible that there are multiple causes for the same event-in this case, dropping the phone COULD have caused the event, or not, but based on the evidence given, she cannot claim that dropping it did NOT cause the event simply because the event happened for other reasons in the past.
Example Question #193 : Lsat Logical Reasoning
Nutritionist: Consumption of too much sugar may increase the risk of diabetes and insulin resistance in many people. These people can eliminate their risk of diabetes and insulin resistance without reducing their sugar intake if they increase their consumption of whole grains such as wheat bread, because the fiber in whole grains helps reduce the negative effects of sugar on insulin response.
Which of the following best expresses a flaw in the nutritionist's reasoning?
The nutritionist assumes that fiber is the only way to counteract the negative effects of sugar.
The nutritionist fails to recognize that reducing sugar intake can have other health benefits.
The nutritionist fails to consider that increasing consumption of whole grains alone will not reduce the effects of sugar on the insulin response enough to eliminate the risk of diabetes and insulin reduction.
The nutritionist fails to consider that some people are allergic to whole grains.
The nutritionist takes for granted that the fiber in whole grains has no negative side effects.
The nutritionist fails to consider that increasing consumption of whole grains alone will not reduce the effects of sugar on the insulin response enough to eliminate the risk of diabetes and insulin reduction.
While some of the incorrect answer choices may be true (it's reasonable to say that reducing sugar intake does have health benefits beyond reducing or eliminating risk of diabetes and insulin resistance) they do not address a flaw in the nutritionist's reasoning (that increasing whole grain consumption alone is sufficient to eliminate the risk of diabetes and insulin resistance because of fiber's ability to reduce negative effects of sugar on insulin response). It's possible that the fiber in whole grains doesn't reduce the negative effects enough to eliminate the risk altogether.
Example Question #34 : Flaw
Every attractive person is confident in their own skin. Mike is a smart, young professional who is confident in his own skin. He also has a beautiful, long-term girlfriend. He must also be attractive.
Which of the following best expresses the flaw in the reasoning outlined above?
Fails to consider whether Mike is confident in his own skin.
Infers that the attractiveness of one's partner is indicative of one's own attractiveness.
Illicitly uses the word "attractive" in two different meanings.
Mistakes a condition that could be true for one that could never be true.
Mistakes a sufficient condition for a necessary one.
Mistakes a sufficient condition for a necessary one.
From the beginning of this passage, it is clear that it is necessary for a person to be confident in their own skin in order to be attractive. But we know nothing about whether a person who is confident in their own skin (and is a young, successful professional with a beautiful girlfriend) must also be attractive.
Example Question #35 : Flaw
Several leading experts in the field of economics have predicted that the rate of growth in Yakistan will increase of the next few years. However, one Professor from the University of Kazubistan has conclusively proven that economic predictions tend to be unreliable. Therefore, we can conclude that Yakistan will experience negative growth for the next few years.
Which one of the following best explains in the flaw in the reasoning above?
It relies on the testimony of leading experts in the field of economics who may have an incentive to overstate their findings for political reasons.
It does not specify what it means to experience negative growth.
It assumes that if we cannot make accurate predictions about a situation that the opposite of the predictions is correct.
It relies on a Professor with unspecified qualifications.
It relies on an ambiguous use of the term “growth.”
It assumes that if we cannot make accurate predictions about a situation that the opposite of the predictions is correct.
The major flaw in the reasoning of the passage is that the stimulus in no way proves that Yakistan will experience negative growth. Simply showing that a prediction of positive growth may be inaccurate does not prove the opposite statement. Only the correct answer shows this flaw. The other answers either are irrelevant or not an actual flaw in the stimulus.
Example Question #36 : Flaw
Russell: Not all high-carbohydrate diets are unhealthy. Several conclusive studies have shown that people on high-carbohydrate diets can obtain a full complement of healthy foods.
Steven: You are wrong to assert that high-carbohydrate diets cannot be unhealthy. Eating a lot of carbohydrates can prevent people from consuming nutritious vegetables and fruits. Also, people whose diets are heavy in carbohydrates tend to engage in risky behavior that reduce their standards of living.
Steven’s response to Russell is most vulnerable to the criticism that his reply
Takes for granted that carbohydrates are unhealthy.
Relies on an ambiguous use of the term “unhealthy.”
Is directed against an argument that Russell did not make.
Does not disprove the argument that risky behavior is actually associated with a healthier lifestyle
Uses complex language to ignore the issue Russell is attempting to raise.
Is directed against an argument that Russell did not make.
Steven’s response to Russell is non-responsive. Russell is only saying that it is possible to be healthy even if you have a high-carbohydrate diet. Steven only points out scenarios where one’s health is compromised by having a diet heavy in carbohydrates but does not prove that it is impossible to have a healthy diet that is heavy in carbohydrates. The correct answer points out this problem.
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