LSAT Logical Reasoning : Weaken/Undermine

Study concepts, example questions & explanations for LSAT Logical Reasoning

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Example Questions

Example Question #71 : Lsat Logical Reasoning

As a society, we have no excuse for the prevalence of chronic dehydration. The remedy is simply too obvious and accessible. Those who suffer from the condition seek doctors’ opinions and medications, suffer from unexplained dizziness and other symptoms, and are susceptible to sickness. To solve these problems and to increase energy and focus, these people need only to drink more water—either by itself or as a primary ingredient in other beverages.

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

Possible Answers:

Some remedies, other than drinking more water, effectively treat chronic dehydration

Most people are unaware of the consequences of chronic dehydration

Many people who are not chronically dehydrated suffer from the same symptoms that are caused by chronic dehydration

Many who are chronically dehydrated have more energy and focus than the average person

Many people who suffer from chronic dehydration are unable to drink more water

Correct answer:

Many people who suffer from chronic dehydration are unable to drink more water

Explanation:

The point of the passage is that there is no excuse for the prevalence of chronic dehydration because increased water consumption provides a simple, effective remedy. That point is directly undermined if those who suffer from the condition cannot consume more water.

Example Question #11 : Weaken/Undermine

Cleaning supply labels often carry warnings regarding the dangers of combining certain chemicals. The reason for this is that combinations of common household cleaning supplies have resulted in serious injuries.  Nonetheless, after purchasing potentially harmful chemicals, customers casually place them near each other, apparently unaware of the consequences should the chemicals be combined.  Most people are placed in grave danger by the contents of their cleaning closets. 

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

Possible Answers:

The warning labels on dangerous cleaning supplies are generally large enough to be easily read

Household chemicals are not often intentionally combined

Some people store cleaning supplies in various locations to avoid accidentally combining them

Most people purchase cleaning supplies in amounts too small for the chemicals to be dangerous when combined

Businesses often purchase greater quantities of cleaning supplies than individuals

Correct answer:

Most people purchase cleaning supplies in amounts too small for the chemicals to be dangerous when combined

Explanation:

The argument suggests that combinations of certain cleaning supplies can lead to serious injuries and that most people are in danger as a result.  The argument is weakened if most people do not purchase enough of the chemicals to be in danger.

Example Question #11 : Determining Which Answer Most Weakens The Argument

Recent studies demonstrate that homeowners who decorate their homes with tranquil scenes, whether paintings or photos, feel peace and comfort.  Those who feel anxiety or restlessness should decorate their homes with images of tranquil scenes.  By doing so, they can increase feelings of peace and comfort.

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

Possible Answers:

Homeowners who feel anxious and restless often have no decorations in their homes

Homeowners who decorate with tranquil scenes often do so to increase feelings of peace and comfort

Homeowners who decorate their homes with living plants also have feelings of peace and comfort

Homeowners often decorate their homes with tranquil scenes because they already feel peace and comfort

Homeowners who feel anxiety and restlessness have the ability to decorate their homes with tranquil scenes

Correct answer:

Homeowners often decorate their homes with tranquil scenes because they already feel peace and comfort

Explanation:

The argument suggests that, because those who decorate with tranquil scenes feel peace, others can increase feelings of peace by decorating with tranquil scenes.  This assumes that the tranquil scenes cause the feelings.  This key assumption is weakened if those who decorate with tranquil scenes do so because they already feel peace and comfort.

Example Question #11 : Determining Which Answer Most Weakens The Argument

Video games have been getting progressively more violent over the past twenty years. Likewise, there has been an increase in violent incidents among high school students over the same period of time. However, new studies show that the majority of the perpetrators of such violent behavior have not spent significantly more time playing violent video games than the average student. Therefore, exposure to video game violence is not a significant influence in the majority of these violent incidents.

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

Possible Answers:

Those who develop violent tendencies in childhood are more likely to seek out and participate in violent video games.

Over the past twenty years, high school students who do not play violent video games have been involved in fewer violent incidents than those who do play.

The average high school student spends significantly more time playing violent video games than high school students did twenty years ago.

Most of the perpetrators of violent incidents had not exhibited such behavior prior to their exposure to violent video games.

Most of the perpetrators of violent incidents who were interviewed admitted that they enjoyed playing violent video games.

Correct answer:

Most of the perpetrators of violent incidents had not exhibited such behavior prior to their exposure to violent video games.

Explanation:

The argument’s conclusion is that exposure to video game violence is not a significant influence in the majority of violent incidents among high school students. While it does not definitively show causation, the fact that many students were not violent prior to being exposed to such video games and were violent afterwards is strong evidence of influence.

Example Question #12 : Weaken/Undermine

The university’s star basketball player has been scoring half as many points this year as he did last year. In the middle of the season, his mother passed away, causing speculation that he had entered into a deep depression. His mother’s death appears to have not only affected his emotional state, but to also have interfered with his game. 

Which of the following, if true, weakens the argument as to why the basketball player’s performance has been declining?

Possible Answers:

The basketball player’s performance had dramatically declined during the first half of the season. 

A recent study suggests that grief following the death of a loved one can have a detrimental affect on athletic performance because it negatively impacts the ability to focus and maintain an optimistic state of mind. 

Some coaches have stated that the death of a loved one can be a great motivator for athletes, as they inculcate a newfound motivation to do their best.

The basketball player’s mother was not very involved in his life, and was often verbally abusive. 

The basketball player was often heard speaking woefully about his mother before and after practice. 

Correct answer:

The basketball player’s performance had dramatically declined during the first half of the season. 

Explanation:

Given that the basketball player’s mother died in the middle of the season, if his performance had declined in the first half of the season, it would have declined due to factors that were independent of his mother’s death. Therefore, this is the correct answer. 

Example Question #13 : Weaken/Undermine

Yogurt aids digestion due to the bacteria that it contains. This is because the bacteria cultures are beneficial to human internal organs, allowing them to function more effectively. However, not all yogurts contain active bacteria cultures, and rather than being made purely with milk, use cornstarch and other additives in order to thicken them and give them the consistency of true yogurt. These yogurts cannot aid digestion.

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

Possible Answers:

Cornstarch has been found to aid digestion. 

Although rare, there are cases in which people have been completely unable to digest the bacteria found in yogurt. 

All yogurt contains bacteria, even in trace amounts. 

The bacteria found in yogurt can have negative health side effects if consumed in excessive quantities. 

It is the amino acids in milk-based yogurt that actually aid digestion, not the bacteria, which is produced as a byproduct. 

Correct answer:

It is the amino acids in milk-based yogurt that actually aid digestion, not the bacteria, which is produced as a byproduct. 

Explanation:

The argument is setting forth the contention that yogurt is good for digestion because of the bacteria it contains. However, if yogurt was actually found to be good for digestion for another reason, and not because of the bacteria it contains -- such as the types of amino acids that it contains -- the chain of logic in the argument would deteriorate. 

Example Question #12 : Weaken/Undermine

Cell phone technology has progressed more quickly than almost anyone could have predicted. Only fifteen years ago was it even conceivable that handheld devices might be able to both store large amounts of data and access the internet. Yet, just a few years later, cell phones accomplish both of these things and are readily accessible to the public. While technology usually advances at predictable, moderate speed, advancements during some periods are so rapid as to be truly remarkable. The development of the cell phone provides an example of just such a time.

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

Possible Answers:

Cell phones are not readily accessible, even now, in many parts of the world

Stages of rapid development have occurred periodically for at least four centuries

Although cell phone capabilities changed drastically over the last fifteen years, the technology behind the changes developed at a predictable, moderate speed

Modern cell phones have often been used to commit sophisticated financial crimes that were previously impossible

Cell phones that cannot access the internet are still used

Correct answer:

Although cell phone capabilities changed drastically over the last fifteen years, the technology behind the changes developed at a predictable, moderate speed

Explanation:

The key assertion of the argument is that cell phone development illustrates a phenomenon of rapid technological development.  This assertion is directly undermined if cell phone technology actually developed at predictable, moderate speeds.

Example Question #14 : Weaken/Undermine

Historically, there has been little need for the law to directly protect privacy rights.  Before the internet was widely used, trespassing laws prohibited violations of privacy within homes.  The internet, however, has changed everything.  Now, companies monitor the websites people visit and sell data gathered about individuals.  While some economic benefits accompany these intrusions, privacy interests are sacrificed.  New laws are needed to address modern privacy concerns.

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

Possible Answers:

Historically, trespass laws that prohibit violations of privacy have often been ignored

Those who use the internet are generally unaware that companies monitor the websites people visit and sell data collected about individuals

Without the ability to monitor the use of websites, many popular websites would not be able to function

Individuals, in addition to companies, monitor the websites people visit

Current trespass laws prohibit companies from monitoring the websites people visit and selling data gathered about individuals

Correct answer:

Current trespass laws prohibit companies from monitoring the websites people visit and selling data gathered about individuals

Explanation:

The argument claims that trespass laws once prohibited violations of privacy but are now inadequate because of new types of privacy violations.  The argument is directly undermined if trespass laws prohibit both old and modern privacy violations. There would no longer seem to be a need for new laws.

Example Question #15 : Weaken/Undermine

Professor: I cannot agree with the common sentiment that there should be fewer math requirements for children. While few children will directly use math for their careers, studying math strengthens important skills. Through math classes, children learn to follow complex instructions, reason, and confirm results. These skills are valuable for life and careers. Besides, most other subjects that children learn are also only indirectly useful.

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

Possible Answers:

Those who support reducing math requirements usually advocate reducing requirements for other subjects as well

Some skills are more important for life and careers than following complex instructions, reasoning, and confirming results

Children learn to follow complex instructions, reason, and confirm results from subjects other than math

Most employers do not require employees to follow complex instructions or confirm results

Most employers do not require employees to have strong math skills

Correct answer:

Children learn to follow complex instructions, reason, and confirm results from subjects other than math

Explanation:

The professor suggests that math requirements should not be reduced because math teaches children three particular skills.  The professors argument is severely weakened if other subjects also teach children those skills.

Example Question #12 : Weaken/Undermine

Company Executive: James should not be promoted to Assistant Manager. Sales figures for the past six months show that three other employees in the same division had more sales than James did over that period of time. As you know, we base our promotions almost solely on an employee's ability to sell.

Which one of the following, if true, most seriously weakens the company executive's argument?

Possible Answers:

Company sales overall have decreased in the past six months.

Two of the three employees who outsold James over the six-month period have not been working at the company as long as James has.

All three of the employees who had more sales than James over the past six months have been promoted more recently than James.

Last year, James won the award for "Most Improved Salesman" in his division.

James, due to his friendly personality, has been assigned to handle especially difficult clients over the past six months, and sales among those clients increased over that period.

Correct answer:

James, due to his friendly personality, has been assigned to handle especially difficult clients over the past six months, and sales among those clients increased over that period.

Explanation:

The correct answer choice is the one that most directly indicates James' ability to sell, which the executive noted is the most important factor in determining company promotions. If James was assigned especially difficult clients, that would explain the overall discrepancy between his sales and others' sales. Further, the fact that sales increased among those clients is a strong indicator of James' relative ability. The other answer choices emphasize factors that, while they may be relevant, are not as significant to the argument.

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