LSAT Logical Reasoning : Determining which answer most weakens the argument

Study concepts, example questions & explanations for LSAT Logical Reasoning

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Example Questions

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Example Question #1 : Weaken/Undermine

While tablet computer sales have increased steadily over the last 2 years, we can expect a reversal of this trend in the near future. Since they became popular in the marketplace 5 years ago, 60 percent of tablet computers sold have been purchased by people from 18 to 25 years of age, and the number of people in this age group is expected to decline steadily over the next 15 years.

Which of the following, if true, would most seriously weaken the argument?

Possible Answers:

Sales of tablet computers to small businesses has declined over the past 2 years.

New technology will make new computing options available over the next 15 years.

Most people under the age of 18 have never purchased a tablet computer.

Most purchasers of tablet computers over the past 2 years have been over the age of 25.

The number of different types of tablet computers available is likely to increase in the near future.

Correct answer:

Most purchasers of tablet computers over the past 2 years have been over the age of 25.

Explanation:

The correct answer suggests that the predicted demographic shift may not have the impact on tablet computer sales that the author predicts. That is, the author uses 5-year demographic data to predict a reversal in the 2-year tablet sales trend. However, the correct answer suggests that such data is misleading insofar as purchasers in the 18 - 25 demographic were not responsible for driving the 2-year sales trend.

Example Question #2 : Weaken/Undermine

Those who go to college are wasting their money. The vast majority of college graduates are employed in fields that do not require their specializations, while others are unemployed. Further, contrary to common belief, the average college graduate is not paid substantially more than the average worker who is not a college graduate.

Which of the following, if true, most weakens the argument?

Possible Answers:

Very few college graduates say they regret attending college

College graduates are more likely to be employed than those who are not college graduates

Certain professions highly prefer or require a college degree as a condition of employment, while no employers prefer an employee not be a college graduate

There are more college graduates now than at any other time in history

The average college graduate has more debt than the average non graduate

Correct answer:

College graduates are more likely to be employed than those who are not college graduates

Explanation:

The argument asserts that college graduates do not have a substantial employment advantage over non graduates. That assertion is directly undermined if college graduates are more likely to be employed than non graduates.

Example Question #3 : Weaken/Undermine

Cities benefit from hosting major sporting events, such as bowl games and major basketball tournaments, but hosting these events also presents challenges. Visitors provide business for hotels, restaurants, and stores, supporting those businesses and increasing tax revenue. On the other hand, with the influx of tourists, police forces and hospitals are often understaffed. Historically, these cities have been able to obtain enough outside workers to sufficiently meet their temporary staffing needs. For that reason, the benefits outweigh the challenges for the cities scheduled to host the next major sporting events.

Which of the following, if true, most undermines the argument?

Possible Answers:

There are expected to be more tourists at future major sporting events than there have been at past events

The businesses in the next cities hosting major sporting events do not require new customers

Increased tourism is not a critical need for the cities hosting the next major sporting events

The cities that will be hosting the next major sporting events are remote and will not be able to obtain any outside workers

The next cities to host major sporting events have larger police forces and hospital staffs than cities that have hosted the events in the past

Correct answer:

The cities that will be hosting the next major sporting events are remote and will not be able to obtain any outside workers

Explanation:

The argument asserts that benefits outweigh challenges for future cities because past cities have been able to bring in outside workers. The argument is directly undermined if future cities will not be able to bring in these workers.

Example Question #4 : Weaken/Undermine

I saw John running through the rain to get to his next class.  Even though he forgot his umbrella today, he accomplished nothing by running instead of walking.  People get just as wet running in the rain as they do walking, even though they may arrive at their destinations more quickly. 

Which of the following, if true, most weakens the argument?

Possible Answers:

John arrived at class more quickly than if he had walked

John ran to class in order to get there more quickly

John did not have to run very far to get to class

John was using an umbrella

John runs more quickly than most people

Correct answer:

John ran to class in order to get there more quickly

Explanation:

The argument claims that John accomplished nothing by running, but assumes that his objective was to avoid getting wet.  If John's goal was to get to class more quickly, then he accomplished something despite getting wet.

Example Question #5 : Weaken/Undermine

Businesses that invest in renewable energy tend to view profit as secondary to social responsibility. Investments in renewable energy are also very risky and several have been known to cause their company very large losses. Therefore, it is a bad idea for you to invest in renewable energy.

Which on the following, if true, most weakens the argument presented above?

Possible Answers:

Companies that focus on social responsibility first tend to have lower profits.

Typically, companies that have very big losses go bankrupt within a year.

Companies that invest in renewable energy compensate for their high risk by diversifying the energy sources they use.

Many investment strategies dictate that you should diversify your portfolio.

Most businesses do not invest in renewable energy.

Correct answer:

Companies that invest in renewable energy compensate for their high risk by diversifying the energy sources they use.

Explanation:

Only the correct answer shows how one of the arguments use to justify not investing in renewable energy companies could in fact be wrong. This weakens the argument by removing one of the pillars that support it.

Example Question #1 : Determining Which Answer Most Weakens The Argument

Modern workers are less competent than workers of the past.  This fact likely comes as a surprise to some because standards are higher than ever.  Employers demand higher degrees than before and more workers have bachelor's and master's degrees than at any other time.  Higher degrees do not mean more competent workers, however.  Recent evidence indicates that modern workers have poor writing ability, lack focus, and are inept at personal communication.

Which of the following, if true, most undermines the argument?

Possible Answers:

Modern workers are dismissed from their jobs less frequently than at any other time

In the past, it was often more difficult to obtain a bachelor's or master's degree

Workers of the past often obtained bachelor's and master's degrees

Workers of the past had poor writing ability, lacked focus, and were inept at personal communication

Modern workers generally work more hours than workers in the past

Correct answer:

Workers of the past had poor writing ability, lacked focus, and were inept at personal communication

Explanation:

The passage describes three weaknesses of modern workers.  This evidence insufficiently supports the conclusion, however, if workers from the past have the same weaknesses as modern workers. 

Example Question #2 : Determining Which Answer Most Weakens The Argument

Foreign trade with other countries will improve quickly if we amend the Constitution so that the President can execute trade agreements with other countries without the current rule requiring a 2/3 approval of the Senate. This is because obtaining a 2/3 vote in the Senate allows extensive debate regarding the merits of a prospective trade agreement, but the process to obtain this 2/3 vote is extremely slow and cumbersome. 

Which one of the following, if true, most seriously weakens the argument?

Possible Answers:

The process to obtain a 2/3 vote in the Senate, which consists of thorough research and deliberation, prevents the implementation of trade agreements that would have negative effects on trade. 

Companies make decisions based on proposed free-trade agreements.

Some improvements in trade are due to other factors besides trade agreements.  

Some senators are willing to support a proposed trade agreement if a President from the same political party negotiates it.

Most senators would refuse to support an amendment to the Constitution that would limit their power.

Correct answer:

The process to obtain a 2/3 vote in the Senate, which consists of thorough research and deliberation, prevents the implementation of trade agreements that would have negative effects on trade. 

Explanation:

The author argues that the rule requiring 2/3 Senate approval for trade agreements should be eliminated so that trade relations can improve quickly.  To weaken this argument, the contention that a sped-up process is the best approach should be attacked.  The answer choice: “The process to obtain a 2/3 vote in the Senate, which consists of thorough research and deliberation, prevents the implementation of trade agreements that would have negative effects on trade” demonstrates that a slow, deliberate process is the superior approach in regards to trade and that we should not rush the process.  Therefore, this is the correct choice. 

Example Question #8 : Weaken/Undermine

Professor: A British scholar criticized a recent publication on John Milton’s Paradise Lost, written by a colleague of mine. Specifically, the British scholar lambasted the thesis, calling it a “publicity stunt,” formulated simply to generate attention, and said that it was not a scholarly product. However, you should know that the British scholar and my colleague have personal distaste towards one another. Given that the British scholar’s criticism of my colleague is based on mere personal bias, my colleague’s thesis is clearly a product of scholarship. 

The reasoning in the professor’s argument is most vulnerable to criticism on the grounds that

Possible Answers:

The professor falsely implies that “scholarly product” and “product of scholarship” mean the same thing. 

The professor did not discuss the content of the thesis at all, and is simply offering his own opinion as evidence as to the character of his colleague’s thesis. 

The professor frames a “publicity stunt” and “product of scholarship” as being opposite when they are not. 

The professor himself is biased because he seems to be defending his colleague based solely on their personal relationship. 

The professor assumes that because there are personal tensions between the British scholar and his colleague, that the colleague’s thesis must be based on scholarly merit, when in fact it may have been a publicity stunt. 

Correct answer:

The professor assumes that because there are personal tensions between the British scholar and his colleague, that the colleague’s thesis must be based on scholarly merit, when in fact it may have been a publicity stunt. 

Explanation:

The problem with the professor's reasoning is that he assumes a fact (that the work was a scholarly product) based on the circumstance that his colleague and the British scholar had personal tensions. There is not a causal relationship between these two circumstances. Therefore, the professor made an error in his causal reasoning. The correct answer conveys this most effectively. 

Example Question #9 : Weaken/Undermine

Microwaves heat objects by exciting the molecules, causing them to move faster. However, microwaves are larger than the size of an ant. Therefore, an ant is not affected by microwaves and can survive exposure to them while most other animals would be killed by such exposure.  

Which of the following, if true, would most seriously weaken the conclusion of the argument?

Possible Answers:

Although microwaves excite molecules, the extent to which this causes objects to heat up depends largely on their water content. 

There are many other animals that are also resistant to microwaves because they are smaller than the microwave itself. 

Not all ants are capable of surviving exposure to microwaves. 

The fact that microwaves are larger than an ant does not prevent the waves from entering them. 

Ants are naturally resistant to external forces due to their hearty exterior. 

Correct answer:

The fact that microwaves are larger than an ant does not prevent the waves from entering them. 

Explanation:

In order to see what statement would weaken the reasoning, we should look more closely at the reasoning in the excerpt:

"Microwaves heat objects by exciting the molecules, causing them to move faster. However, microwaves are larger than the size of an ant. Therefore, an ant is not affected by microwaves . . . "

The correct answer choice introduces information that disrupts the conclusion. If microwaves can enter an ant, it would in fact affect them, and thereby overturn the conclusion. 

The statement in the correct answer most closely relates to the chain of logic. The incorrect answer choices are too tangentially related to the chain of logic to be correct. 

Example Question #10 : Weaken/Undermine

Environmental activists who primarily focus on reducing carbon emissions are misguided. There are many environmental issues that should be of great concern, including some that present more serious challenges than carbon emissions.  Water pollution, for example, has devastating results on the environment.  Activists who primarily focus on carbon emissions apparently do not recognize that water pollution and other issues cause damage to the environment.

Which of the following, if true, most seriously weakens the argument?

Possible Answers:

Some environmental activists focus attention on both water pollution and carbon emissions

Some environmental concerns pose greater dangers than both water pollution and carbon emissions

For many years, carbon emissions did pose a more serious threat to the environment than did water pollution

Some environmental activists primarily focus on reducing carbon emissions because there is greater opportunity for progress in that area than in others

Most environmental activists primarily focus on water pollution

Correct answer:

Some environmental activists primarily focus on reducing carbon emissions because there is greater opportunity for progress in that area than in others

Explanation:

The purpose of the passage is to propose that environmental activists who primarily focus on carbon emissions are misguided.  The claim that other issues are also important is only a part of the larger argument.  The reasoning is weakened if some activists are focused on carbon emissions because that area provides greater opportunity for change; they are less likely to be misguided.

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