LSAT Logical Reasoning : LSAT Logical Reasoning

Study concepts, example questions & explanations for LSAT Logical Reasoning

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Example Questions

Example Question #4 : Determining The Flaw In The Argument

The new music genre, “Eastern Vibe” has elements of different music genres. It has influences from Electronica, Dub Step, Rock, and Pop in its composition. Since it has no element in its composition that is original, it follows that the composition of “Eastern Vibe” cannot be considered original.

Which one of the following is a reasoning error made in the argument?

Possible Answers:

assuming that because something is true of each of the parts of a whole it is true of the whole itself.

generalizing the instances of a few to all instances.

interpreting a factor as a necessity rather than as a want.

presupposing what is to be proved by contradicting a claim.

deriving a conclusion from preferences rather than evidence.

Correct answer:

assuming that because something is true of each of the parts of a whole it is true of the whole itself.

Explanation:

The author argues that the new musical genre copied elements of other genres and is therefore not original. This argument does not necessarily follow as there could be other elements of the genre that are original such as the use of new instruments and sounds or the amalgamation of different sounds to form a new coherent genre. Therefore, something can be true of a whole without it being true of its parts; thus the author makes the error described in the answer choice: “assuming that because something is true of each of the parts of a whole it is true of the whole itself.”

Example Question #3 : Flaw

Doctor X: I disagree with Doctor Y’s proposed treatment plan for Mr. Jones. Doctor Y recommends that Mr. Jones undergo surgery because he is in substantial pain. However, Mr. Jones cannot afford to pay for the procedure or the cost of the hospital stay.

The reasoning in Doctor’s X’s argument is flawed because the argument:

Possible Answers:

engages in ad hominen attacks

uses evidence concerning the economic feasibility of acting on a recommendation as a basis for questioning of the validity of the recommendation

fails to analyze the issue presented in terms of what is best for the patient

compares the use of short-term versus long-term analysis

does not take into account the comforts and amenities of the hospital where the procedure will be performed

Correct answer:

uses evidence concerning the economic feasibility of acting on a recommendation as a basis for questioning of the validity of the recommendation

Explanation:

Doctor X only focuses on whether Mr. Jones can afford the procedure and does not discuss the medical merits of Doctor Y’s recommendation. Therefore, there is a scope shift. In other words, just because Mr. Jones cannot afford Doctor Y’s recommendation does not mean that his recommendation is suspect. This is reflected in the correct answer choice that states Doctor X’s flawed argument, “uses evidence concerning the economic feasibility of acting on a recommendation as a basis for questioning of the validity of the recommendation.”

Example Question #3 : Flaw

Mayor: Critics of the Healthy Eating Bill are delaying passage of this important law because they disagree with the more narrow definition of the term “unhealthy foods.” However, this legislation will place stricter limits on the type of foods that will be available to the public than our current laws. Therefore, by splitting hairs over semantics, these critics show their apathy to the public’s health.

The Mayor’s reply to the opponents of the Healthy Eating Bill is most vulnerable to which of the following criticisms?

Possible Answers:

It fails to adequately recognize the possibility that the definition of the term “unhealthy foods” determines the impact of the legislation.

It connects the motives of those who oppose the bill with the motives of those who produce soda.

It assumes that does who seek to defeat the Bill will profit from its defeat.

 It attempts to defend the reputation of the author of Bill rather than the merits of the actual Bill.

It labels the critics of the Bill as supporters of the fast food industry.

Correct answer:

It fails to adequately recognize the possibility that the definition of the term “unhealthy foods” determines the impact of the legislation.

Explanation:

The Mayor’s statement that the critics are “splitting hairs over semantics” indicates that he does not believe that the definition of the term "unhealthy foods" makes a difference to the argument. However, this is only his opinion. In actuality, a more restrictive, narrow definition of the term “unhealthy foods” may make significant difference to the critics of the bill. For example, a definition that excludes foods reputedly considered harmful to the public such as one that includes high fructose corn syrup or trans fat would not have the same impact as one that does; thus, support or criticism for the bill could turn on the definition of “unhealthy foods.” Therefore, the correct choice is: “It fails to adequately recognize the possibility that the definition of the term “unhealthy foods” determines the impact of the legislation.”

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:

Possible Answers:

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 

does not take into account the advent of the germ theory of disease

does not distinguish between those diseases that are treatable and those that are not

presupposes that Army 2 is superior to Army 1

Correct answer:

fails to take into account other factors that may have caused disease

Explanation:

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 #12 : Flaw

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:

Possible Answers:

draws a conclusion that simply restates a claim given in support of that conclusion

blames senators for problems that are outside of their control

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

does not distinguish between doing what is best for one’s constituents and acting in accordance with the preferences of one’s constituents

Correct answer:

draws a conclusion that simply restates a claim given in support of that conclusion

Explanation:

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 #13 : 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

Possible Answers:

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

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

Correct answer:

predicts a future event from past events that may have no relationship to the predicted event

Explanation:

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 #14 : Flaw

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

Possible Answers:

treats a merely necessary condition as though it were a sufficient condition

falsely equates the terms consultation and diagnosis, when one does not necessarily lead to the other

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

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

Correct answer:

presumes, without further justification, that a doctor's experience in evaluating patients likely determines the accuracy of his or her diagnosis

Explanation:

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 #15 : Flaw

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

Possible Answers:

assumes that the standards of written screenplays nowadays are lower based solely on the prevalence of special effects and computer graphics

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

fails to consider the possibility that audience’s attention spans were longer fifty years ago, and thus they were more easily entertained

downplays the importance of acting and directing in determining the box office success of films

Correct answer:

assumes that the standards of written screenplays nowadays are lower based solely on the prevalence of special effects and computer graphics

Explanation:

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 #11 : 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:

Possible Answers:

confusing cause and effect.

assuming that a condition precedent has already occurred. 

relying on information that does not have a credible source. 

relying on a sample size that is too narrow.

mistaking correlation for causation. 

Correct answer:

mistaking correlation for causation. 

Explanation:

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 #17 : Flaw

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

Possible Answers:

presumes that the rights to most movies and music will be given to digital media content providers

fails to take into account the possibility that some digital movies and music are illegally downloaded

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 provide a source for its claim that digital download trends are likely to continue

fails to define the terms “manufacturing” and “labor”

Correct answer:

presumes, without providing justification, that an increase in sales of one type of media necessarily leads to a decrease in sales of another type

Explanation:

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.

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