LSAT Logical Reasoning : Determining the flaw in the argument
Study concepts, example questions & explanations for LSAT Logical Reasoning
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Example Questions
Example Question #11 : Flaw
The two opposing armies, Army 1 and Army 2, are the same in regards to size. Since certain diseases that have recently afflicted Army 1 can be attributed to its crowded conditions in its encampment, such diseases must also afflict Army 2.
The reasoning in the argument is most vulnerable to the criticism that it:
does not distinguish between those diseases that are treatable and those that are not
fails to take into account other factors that may have caused disease
fails to indicate whether the average life expectancy is lower in Army 1 than Army 2
presupposes that Army 2 is superior to Army 1
does not take into account the advent of the germ theory of disease
fails to take into account other factors that may have caused disease
The author comes to the hasty conclusion that two armies that share the same size will share the same problem (here disease) associated with the density of their encampments. The author assumes that no other factor could influence the issue, which is not true; e.g. different sanitation procedures, more or better skilled medical personnel, etc. could also influence the incidence of disease. This failure to take into account other alternative explanations is the correct answer choice, “fails to take into account other factors that may have caused disease.”
Example Question #11 : Determining The Flaw In The Argument
Many senators do not listen to their constituents, nor are they reactive to the preferences of the people in their state. These politicians might state that they are acting in accordance with the preferences of the people in their state, but they really are not listening to their constituents because without being reactive to the preferences of the people in their respective states, it is impossible to listen to their constituents. It is clear from this that senators who do not listen to their constituents will be incapable of being reactive to the preferences of people in their state.
The argument above is logically suspect because it:
does not consider the impact of negative attack advertising
fails to take into account that not every senator wants to listen to his political party instead of his constituents
blames senators for problems that are outside of their control
draws a conclusion that simply restates a claim given in support of that conclusion
does not distinguish between doing what is best for one’s constituents and acting in accordance with the preferences of one’s constituents
draws a conclusion that simply restates a claim given in support of that conclusion
Circular reasoning assumes the conclusion and is when the evidence and conclusion are functionally identical. Here, this is the case, and both the evidence and the conclusion are rewrites of each other. Thus, the correct answer choice is, “draws a conclusion that simply restates a claim given in support of that conclusion.”
Example Question #12 : Flaw
Meteorologist: The average temperature last winter was 30 degrees fahrenheit. That was the lowest average temperature for a winter in 20 years. The average temperature this winter will most likely be warmer than last winter's average temperature.
The reasoning in the argument is most vulnerable to the criticism that it
suggests that the average temperature in a particular winter can predict the temperature on a particular day
assumes that last winter's average temperature will have no bearing on this winter's average temperature
draws a universal conclusion from information about one event
assumes that last winter's average temperature will determine this winter's average temperature
predicts a future event from past events that may have no relationship to the predicted event
predicts a future event from past events that may have no relationship to the predicted event
The meteorologist did not establish a relationship between past temperatures and future temperatures. As a result, the conclusion does not necessarily follow from the information given. To remedy this flaw, the meteorologist would need to establish that past temperatures predict future temperatures.
Example Question #12 : Determining The Flaw In The Argument
Patient: The doctor who diagnosed my broken leg and recommended I wear a cast for six months has only seen three prior patients with broken legs. Dr. Green, an orthopedic surgeon, has evaluated thousands of patients who had broken legs. Even though a consultation with Dr. Green is more expensive, he will likely give a more accurate diagnosis of my leg than I got from the prior doctor.
The reasoning in the patient's argument is most vulnerable to criticism on the grounds that the argument
treats a merely necessary condition as though it were a sufficient condition
fails to take into account the possibility that Dr. Green may not have been practicing for as long as the other doctor
presumes, without further justification, that a doctor's experience in evaluating patients likely determines the accuracy of his or her diagnosis
falsely equates the terms consultation and diagnosis, when one does not necessarily lead to the other
fails to specify a source for the claim that the doctor who evaluated the patient's leg has only seen three prior patients with broken legs
presumes, without further justification, that a doctor's experience in evaluating patients likely determines the accuracy of his or her diagnosis
The patient’s fundamental assumption is that Dr. Green’s diagnosis will be more accurate simply because he has more experience in evaluating patients. Yet there is no logical reason to assume this. The other doctor’s diagnosis may be accurate regardless of how many patients he has evaluated.
Example Question #13 : Determining The Flaw In The Argument
Movie critic: Films nowadays rely heavily on special effects and computer graphics to entertain audiences. Fifty years ago, when such technology did not exist, films had to rely on well-written plots and dialogue to keep the audience’s attention. It is clear that today’s written screenplays are not held to the same standards they would have been fifty years ago.
The movie critic’s argument is flawed in that it
attacks modern screenplays on an aesthetic basis rather than a logical basis
provides no basis for the assertion that certain technology did not in fact exist fifty years ago
downplays the importance of acting and directing in determining the box office success of films
assumes that the standards of written screenplays nowadays are lower based solely on the prevalence of special effects and computer graphics
fails to consider the possibility that audience’s attention spans were longer fifty years ago, and thus they were more easily entertained
assumes that the standards of written screenplays nowadays are lower based solely on the prevalence of special effects and computer graphics
Nothing in the argument supports the conclusion that screenplay standards have dropped; all we know is that there are more special effects and computer graphics. Whether these entertain audiences more than the screenplay is beside the point. The movie critic does not address the possibility that modern films could still have well-written plots and dialogue regardless of their special effects.
Example Question #14 : Determining The Flaw In The Argument
Cook: Often times when I cook, I find that I can become over-ambitious and prepare multiple dishes at once. As a result, I don’t always pay enough attention to everything that I am preparing and have a tendency to overcook some of my creations. I have heard about a new type of cookware that is designed to prevent overcooking, and am thinking of investing in it so that I can prepare better food.
The cook’s reasoning is flawed because he is:
mistaking correlation for causation.
confusing cause and effect.
relying on a sample size that is too narrow.
assuming that a condition precedent has already occurred.
relying on information that does not have a credible source.
mistaking correlation for causation.
The cookware is correlated to reduced overcooking. However, the chef thinks that the cookware will cause his food to no longer be overcooked, when the cause of such overcooking appears to be his inability to focus on a single dish because of his excessive multitasking. Therefore, the chef mistakes the cookware that he is using as being the cause of his food being overcooked.
The correct answer identifies the cause/ correlation error that the chef has made.
Example Question #15 : Determining The Flaw In The Argument
Market analyst: Physical media, like DVDs and CDs, will not be sold for much longer. In the past five years, digital movie downloads have increased by 60%, and digital music downloads have increased by 70%. These trends are likely to continue, especially when one considers the fact that digital media content providers are not hampered by the manufacturing and labor costs of physical media.
The reasoning in the argument is most vulnerable to criticism on the grounds that the argument
fails to define the terms “manufacturing” and “labor”
presumes, without providing justification, that an increase in sales of one type of media necessarily leads to a decrease in sales of another type
fails to take into account the possibility that some digital movies and music are illegally downloaded
presumes that the rights to most movies and music will be given to digital media content providers
fails to provide a source for its claim that digital download trends are likely to continue
presumes, without providing justification, that an increase in sales of one type of media necessarily leads to a decrease in sales of another type
The argument provides no data indicating that sales of physical media are decreasing, nor does it explain any connection between increased digital media sales and physical media sales. Without additional information, one could assume that both types of media are increasing in sales. The incorrect answer choices do not attack the argument’s reasoning, but focus on other factors which do not necessarily affect the conclusion.
Example Question #16 : Determining The Flaw In The Argument
Beth: We should stop spending so much time and money on climate change research. From the studies I've read, even if it is an issue, it will not significantly affect our lifestyle for thousands of years. With the pressing problems we face today, we cannot afford to expend our resources in such a way. Besides, it's politically divisive.
Stan: So you'd rather we just turn a blind eye and ignore climate change? It's not just future generations that will be affected by these issues. Having environmental awareness right now will help to solve our energy and waste problems, not to mention the impact on health. You have to look at the bigger picture.
Stan's response to Beth's argument is most vulnerable to criticism on which of the following grounds?
It fails to recognize the importance of planning for one's future.
It appeals to evidence which has not been properly supported.
It cites irrelevant data in support of its conclusion.
It presupposes what it seeks to establish, and ignores potential counterevidence.
It attempts to refute a distorted version of an opposing position.
It attempts to refute a distorted version of an opposing position.
Stan's response focuses on awareness of climate change, whereas Beth's argument was about spending time and funding on climate change research. Therefore Stan distorts Beth's position and attempts to argue against the distorted position. The other answer choices, to the extent that they are valid at all, are not nearly as fundamental to Stan's reasoning.
Example Question #18 : Flaw
The government always protects animals that are at risk of extinction. Further, some animals have become extinct even though they were protected by the government. Black bears must be at risk of extinction because the government recently began protecting them.
The argument is flawed because it does which of the following?
Without support, concludes that bears will become extinct because other animals protected by the government have become extinct
Assumes that the government only protects animals that are at risk of extinction
Assumes that some animals are not at risk of extinction
Fails to account for the possibility that some animals at risk of extinction will not in fact become extinct
Determined that black bears only recently became at risk of extinction
Assumes that the government only protects animals that are at risk of extinction
The argument states that all animals that are at risk of extinction are protected by the government. It does not follow from this, however, that only animals at risk of extinction are protected. The government could protect animals at risk of extinction as well as those that are not.
Example Question #17 : Determining The Flaw In The Argument
Sports agent: College athletes should be paid for their efforts; otherwise, there is no incentive for them to stay in college rather than become professionals in their respective sports. After all, college sports are nearly as popular as professional sports nationwide, and billions of dollars are made annually by television stations, athletic conferences, and associations promoting the sports. Yet the student athletes themselves see none of the money as long as they remain students. The way to keep athletes in school is to begin paying them salaries commensurate with what they would receive as professionals.
The reasoning in the sports agent’s argument is most vulnerable to criticism on the grounds that the argument
presumes, without providing justification, that college sports are nearly as popular as professional sports nationwide
uses the key term “professional” in two different senses in various parts of the argument
fails to adequately support the premises in such a manner that the conclusion would follow from those premises
bases its conclusion on subjective criteria rather than an objective assessment of the merits of paying student athletes
fails to consider the possibility that many student athletes do not play college sports with the intention of becoming professionals in those sports
fails to consider the possibility that many student athletes do not play college sports with the intention of becoming professionals in those sports
The argument creates a false dilemma by assuming that all college athletes plan (and are able) to become professional athletes. The paragraph contains no premise which supports this assumption. The remaining answer choices do not properly identify flaws in the argument’s reasoning.
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