LSAT Logical Reasoning : LSAT Logical Reasoning
Study concepts, example questions & explanations for LSAT Logical Reasoning
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Example Questions
Example Question #91 : Lsat Logical Reasoning
The horrors of World War I have been blamed on many of the generals who commanded the armies in the trenches that became so prevalent in that conflict. While it is often said that generals fight the last war, the leaders arguing for bayonet charges into the teeth of a machine gun nest seemed to be unable to see the current war. Trench warfare was unable to be won through Napoleonic tactics, which was sadly proven beyond a shadow of a doubt in the Great War.
Which of the following statements would most weaken the argument presented in the statement?
The use of trenches radically transformed military strategy and tactics.
The military academy education of World War I generals was largely based on Napoleonic tactics.
World War I saw a number of generals take command of the armies with little success.
Many generals in World War I began arguing against charges into machine gun nests.
Training for soldiers at the beginning of World War I heavily featured bayonet training.
Many generals in World War I began arguing against charges into machine gun nests.
The passage argues that the unsuccessful tactics of World War I, including bayonet charges into machine gun nests, were largely due to the generals in the war not understanding the problems with these tactics. If many generals were in fact arguing the utility of such tactics, then the argument would be seriously weakened.
Example Question #92 : Lsat Logical Reasoning
Coffee allows people to stay awake, when they would otherwise have had to go to sleep, because of its caffeine content. According to several recent studies, people who drink coffee actually go to sleep earlier than people who drink no coffee. Therefore, coffee actually makes people go to sleep.
The strongest criticism of the argument is that it:
Cites several studies that are inconsistent with its conclusion.
Concludes that people who do not drink coffee are not drinking other beverages which provide them with a source of caffeine.
Claims something is true without scientific evidence of the proof of it’s factual truth.
Fails to consider other factors which might make someone drink coffee yet also go to sleep early.
Assumes caffeine is present in all coffee.
Fails to consider other factors which might make someone drink coffee yet also go to sleep early.
There are facts in this problem which are intended to throw you off. The caffeine in coffee in this case does not matter. The studies only concluded that people who drink coffee go to sleep earlier than people who do not drink coffee. The problem does not state why, it could be that people who drink coffee are avoiding the higher caffeine content of energy drinks that everyone else drinks or it could be something else. That coffee makes people go to sleep is never stated as a fact. A causal relationship between coffee and sleep was never established.
Example Question #93 : Lsat Logical Reasoning
Students have been shown to become tired shortly after lunch, losing productivity in their afternoon classes and falling behind in these subjects compared to those they have first thing in the morning. Adding physical activities and break periods after lunch should make students perform much better in school.
Which of the following statements would most undermine the conclusion of the above passage?
Students often rate the subjects they take after lunchtime as their least favorite in surveys.
The success of students is highly related to the specific subject being taught.
Teachers express the most frustration with students in afternoon classes.
Academic success is caused by a number of interrelated, separate factors.
Student disciplinary problems occur most often in classes directly after lunch.
The success of students is highly related to the specific subject being taught.
The passage states that students do not do well in their classes after lunch, and that changing these subjects could lead to more academic success. The argument hinges, therefore, on the effect of time of day on student achievement. A statement that would most undermine the argument must be the one that states academic success had no correlation with the time of day.
Example Question #94 : Lsat Logical Reasoning
Motorcycles have repeatedly been proven to be much more dangerous for their drivers than cars. While never as popular a vehicle on the road, motorcycles have a disproportionate number of casualties and fatalities as compared to automobiles. Traffic safety would be greatly improved if motorcycles were banned.
Which of the following statements most undermines the argument in the passage?
Well-trained motorcyclists very rarely have accidents resulting in casualties or fatalities.
The traffic safety records of automobiles are not as good as other forms of transportation.
The safety record of motorcycles is much worse than all other forms of transportation.
Motorcycles have always had a mixed safety record which has paled in comparison to automobiles.
Motorcycle accidents do not always result in casualties or fatalities.
Well-trained motorcyclists very rarely have accidents resulting in casualties or fatalities.
The argument in the passage is that motorcycles are much more unsafe than automobiles, which means that they should be banned. A statement that shows well-trained motorcyclists do not have as bad a traffic safety record would directly undermine the statement that they are so dangerous they should be banned.
Example Question #34 : Weaken/Undermine
The vast majority of cancer drugs have proven to be ineffective. It makes sense, therefore, to turn to natural remedies as a possible solution. In a recent study, 90% of individuals without cancer had normal to high levels of iron in their blood, while only 20% of individuals with cancer had similarly high levels. Clearly, then, supplementing one's diet with iron can help prevent cancer.
Which of the following most weakens the argument outlined above?
The study was not conducted by doctors certified in the treatment of cancer.
Iron can also reduce incidences of heart disease, stroke, and diabetes.
Almost all cancer treatments reduce a patient's iron levels.
Some of the cancer patients exhibited exceptionally high levels of iron in their blood.
The study was conducted with a small sample population.
Almost all cancer treatments reduce a patient's iron levels.
The correct answer disputes the causation implied by the arguments conclusion. Perhaps lower iron levels came after a patient developed cancer. In that case, it is not reasonable to infer that increasing one's intake of iron would prevent the development of cancer.
Example Question #1 : Main Point / Main Conclusion
Doctor: A major study found no causal link between having received an MMR vaccine and having autism, but the study is flawed. The study looked at 500 people who had received an MMR vaccine. Because autism occurs in less than 1% of the population, researchers would need to include many more than 500 people in a study to detect a meaningful increase in the rate of autism.
Which of the following most accurately expresses the main conclusion of the doctor's argument?
Medical professionals should conduct more research into the MMR vaccine to determine whether it is causally linked with autism.
Contrary to the findings of a major study, there is reason to believe that the MMR vaccine causes autism.
A major study that discovered no causal relationship between the MMR vaccine and autism is unreliable.
Researchers cannot determine whether a given disorder is causally linked to a procedure if the base rate for the disorder is less than 1%.
The major study cited does not reach a conclusion as to whether autism results from the MMR vaccine.
A major study that discovered no causal relationship between the MMR vaccine and autism is unreliable.
The passage begins with a fact and the judgment that the study is flawed. The rest of the paragraph explains how it's flawed (i.e., not enough people were included in the study to justify the conclusion). Therefore, the correct answer is the first sentence, because everything else in the passage supports that claim.
Example Question #2 : Determining Which Answer Most Accurately Expresses The Main Idea Of The Argument
While coffee does stain teeth, most claims that coffee has ill-effects are unfounded. There is even some evidence of health benefits. The situation may be different when the arguments relate to people who consume more than a moderate amount of coffee.
Which of the following conclusions most logically follows from the argument?
Moderate coffee consumption will not stain teeth
People who drink coffee in excess are likely to have severe teeth staining
Many purported ill-effects from moderate consumption of coffee are unfounded
Consumed in moderation, coffee has no ill-effects
Moderate consumption of coffee has health benefits while excessive consumption causes ill-effects, including teeth staining
Many purported ill-effects from moderate consumption of coffee are unfounded
The argument does not draw a strong conclusion. It does not assert that coffee is healthy or that it has no negative health effects.
Example Question #1 : Determining Which Answer Most Accurately Expresses The Main Idea Of The Argument
We all have an obligation to do our part to protect nature. Only those who do are environmentally responsible. No people who insist on using incandescent light bulbs do their part to protect nature.
Which of the following conclusions follows:
People who insist on using incandescent light bulbs are not environmentally responsible
All those who do not insist on using incandescent light bulbs are environmentally responsible
Incandescent light bulbs are only used by those who are environmentally irresponsible
Environmentally responsible people have an obligation to discourage others from using incandescent light bulbs
Incandescent light bulbs cause harm to nature
People who insist on using incandescent light bulbs are not environmentally responsible
Only people who do their part to protect nature are environmentally responsible. Those who insist on using incandescent light bulbs do not do their part to protect the environment. It follows that those who insist on using incandescent light bulbs are not environmentally responsible.
Example Question #3 : Determining Which Answer Most Accurately Expresses The Main Idea Of The Argument
Taxpayers have been complaining about the U.S. tax system for many years. The tax system is so complex that very few can understand its provisions. A tax system that can only be understood by a very few people inefficiently generates revenue.
Which of the following is a logical conclusion to the argument?
The U.S. tax system inefficiently generates revenue because its complexity creates loopholes
The U.S. tax system inefficiently generates revenue
Taxpayers complain about the U.S. tax system because it inefficiently generates revenue
The U.S. tax system generates revenue less efficiently than some other systems
Taxpayers would complain about the tax system less if it were less complex
The U.S. tax system inefficiently generates revenue
If the U.S. tax system can only be understood by a few, and tax systems that can only be understood by a few inefficiently generate revenue, then it follows that the U.S. tax system inefficiently generates revenue.
Example Question #2 : Determining Which Answer Most Accurately Expresses The Main Idea Of The Argument
Public transportaion plays less of a role in commuting within cities than it once did, which is unfortunate because the benefits for cities and residents are substantial. Public transportation leads to less traffic congestion, more parking for those who do drive, less stress, less expense, and better air quality. Legitimate downsides to taking public transportation include safety concerns and lengthened commutes. Addressing these concerns would take effort but would also produce tremendous benefits.
Which of the following conclusions best follows from the argument?
While there are significant benefits to public transportation in cities, the substantial downsides explain why it is used less than it once was
It is difficult to explain why fewer people use public transportation than once did because the benefits are substantial for cities and city residents
Public transportation is used less often in cities now than it once was because of safety concerns and longer commutes
If public transportation were used more widely, traffic in cities would run more smoothly and there would be other benefits as well
While there are downsides to public transportation, they could be addressed and public transportation has benefits for both cities and residents
While there are downsides to public transportation, they could be addressed and public transportation has benefits for both cities and residents
While the argument recognizes benefits of public transportation, it does not directly endorse its use, instead, recognizing legitimate downsides as well. On the other hand, the passage is clear that public transportation has real, positive implications for modern cities. Finally, the point of the argument is not to compare the present and past.
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