Summarize Argument
The author concludes that direct-mail advertising is not bad for the environment. This is because direct-mail advertising usually advertises products to be purchased from home. This leads to millions of people buying products from home. If they didn’t purchase these products at home, purchase of these products would require using a car, which would add pollutants to the air.
Notable Assumptions
The author assumes that a significant proportion of the products bought as a result of direct-mail advertising would still be bought had direct-mail advertising not existed. The author also assumes that there’s no aspect of purchases from home that produce more environmental damage than those purchases would have been had they been purchased after using a car.
A
Although the primary intent of most direct-mail advertisers is to convince people to buy products from their homes, direct mail can also lead to increased sales in stores by customers who prefer to see a product prior to purchasing it.
This weakens the argument by showing that direct-mail advertising might increase sales in stores, which would generally require use of a car, which would add pollutants to the air.
B
Most of the products purchased in response to direct-mail advertisements would be purchased even without the direct-mail advertisements.
This confirms that without direct-mail advertising, pollutants from in-person sales would actually have occurred. In theory, direct-mail advertisements might have just caused purchases that otherwise wouldn’t have occurred. (B) eliminates this possibility.
C
A person who receives and reads a direct-mail advertisement is more likely to purchase the product advertised than is a person who reads an advertisement for a product in a magazine that they subscribe to.
The comparative effectiveness of direct-mail ads and magazine ads has no clear impact. We already know that people buy products from home due to direct-mail ads. Even if these are more effective than others, we still don’t know the environmental impact of direct-mail ads.
D
Usually, a company that sends out direct-mail advertisements has good reason to think that the person to whom the advertisement is sent would be more interested in the product than would the average person.
(D), unlike (B) doesn’t establish that the people who buy products from home would have bought those products without the direct-mail ads. There might be signs those people are more interested in the products, but that doesn’t mean they would buy without the ads.
E
Products purchased as the result of direct-mail advertising comprise an increasingly large portion of the consumer products purchased each year.
This doesn’t reveal anything about the environmental impact of direct-mail ads. We still don’t know whether direct-mail ads are causing people to buy from home products that would otherwise be purchased by using a car.
Library preservationist: Due to the continual physical deterioration of the medieval manuscripts in our library’s collection, we have decided to restore most of our medieval manuscripts that are of widely acknowledged cultural significance, though this means that some medieval manuscripts whose authenticity is suspect will be restored. However, only manuscripts whose safety can be ensured during the restoration process will be restored, and manuscripts that are not frequently consulted by researchers will not be restored.
Summary
Most of our medieval manuscripts that are of widely acknowledged cultural significance will be restored, and some medieval manuscripts whose authenticity is suspect will be restored. Only manuscripts whose safety can be ensured during restoration and manuscripts frequently consulted by researchers will be restored.
Notable Valid Inferences
Some medieval manuscipts whose authenticity is suspect are frequently consulted by researchers.
Some medieval manuscripts whose authenticity is suspect can have their safety ensured during restoration.
Most medieval manuscripts that are of widely acknowledged cultural significance are frequently consulted by researchers.
A
Some of the medieval manuscripts whose authenticity is suspect are frequently consulted by researchers.
Must be true. As shown below, we can combine the statements that some manuscripts whose authenticity is suspect will be restored and that only frequently consulted manuscripts will be restored. 
B
All of the medieval manuscripts widely acknowledged to be of cultural significance are manuscripts whose safety can be ensured during the restoration process.
Could be false. The stimulus tells us that most manuscripts widely acknowledged to be of cultural significance will be restored. We cannot infer an “all” statement from a “most” statement.
C
All of the medieval manuscripts whose safety can be ensured during the restoration process are frequently consulted by researchers.
Could be false. As shown on our diagram, there are no necessary conditions attached to the condition of a manuscript’s safety being ensured. It is possible that some manuscripts exist whose safety can be ensured but are not frequently consulted.
D
The medieval manuscripts most susceptible to deterioration are those most frequently consulted by researchers.
Could be false. The stimulus does not give us any information to determine what manuscripts are most susceptible to deterioration. This answer choice is outside of the scope of our conditions.
E
None of the medieval manuscripts that are rarely consulted by researchers is widely acknowledged to be of cultural significance.
Could be false. The stimulus does not give us any information about manuscripts that are rarely consulted by researchers. This answer choice is outside of the scope of our conditions.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that one of the functions of phenazines is to serve as molecular pipelines that give interior bacteria access to essential nutrients in the environment surrounding the colony.
Notable Assumptions
The author assumes that it’s possible for phenazines to have more than one function. The author also assumes that phenazines are able to provide nutrients to interior bacteria.
A
Bacteria colonies that do not produce phenazines form wrinkled surfaces, thus increasing the number of bacteria that are in direct contact with the surrounding environment.
This provides evidence that corroborates the author’s hypothesis. Without phenazines, more bacteria must contact the surrounding environment, possibly to get access to nutrients. This makes the theory that phenazines give interior bacteria access to nutrients more plausible.
B
The rate at which a bacteria colony produces phenazines is determined by the number of foreign bacteria in the environment immediately surrounding the colony.
This connects production of phenazines to foreign bacteria. But this has no clear impact. We want an answer that connects phenazines to the need to access nutrients.
C
When bacteria colonies that do not produce phenazines are buried in nutrient-rich soil, they grow as quickly as colonies that do produce phenazines.
We still have no reason to think phenazines provide nutrients to interior bacteria. If anything, this is in the direction of a weakener, since we might think non-phenazine bacteria shouldn’t grow as quickly when buried in the soil.
D
Bacteria colonies that produce phenazines are better able to fend off other bacteria than are bacteria colonies that do not produce phenazines.
This connects phenazines to ability to fend off other bacteria. But this has no clear connection to the provision of nutrients to interior bacteria.
E
Within bacteria colonies that produce phenazines, interior bacteria are more likely to die than are bacteria along the edges.
It doesn’t help the author’s hypothesis to learn that interior bacteria die more quickly. We would still have no reason to believe phenazines provide nutrients to interior bacteria.
Summarize Argument
The author concludes that apples were probably not cultivated in this region 5,000 years ago. This is based on the following:
Today, wild apples are much smaller than cultivated apples found in supermarkets.
In this region, apples of 5,000 years ago were the same size as wild apples native to the region.
Identify and Describe Flaw
The author assumes that cultivated apples 5,000 years ago must have been larger than wild apples from that time. But this overlooks the possibility that wild apples were similar in size to cultivated apples from that time, even if today wild apples are smaller than cultivated apples.
A
fails to consider that even if a plant was not cultivated in a given region at a specific time, it may have been cultivated in nearby regions at that time
The argument concerns only “this region.” Whether apples were cultivated in other regions does not affect the reasoning of the argument.
B
fails to consider that plants that have been cultivated for only a short time may tend to resemble their wild counterparts much more closely than plants that have been cultivated for a long time
The author overlooks the fact that, 5,000 years ago, cultivated and wild apples might have been more similar in size compared to their relative sizes today. We cannot rely on their relative sizes today to conclude that the smaller apples of 5,000 years ago were not cultivated.
C
takes for granted that all apples are either the size of wild apples or the size of the cultivated apples now found in supermarkets
The argument concerns remains of apples in a particular region that are the same size wild apples. The existence of other apples sized in between wild/cultivated doesn’t weaken the argument. So the author doesn’t need to assume there are only two sizes for apples.
D
employs a premise that is incompatible with the conclusion it is supposed to justify
There is no premise that contradicts the conclusion. The conclusion is that apples probably weren’t cultivated 5,000 years ago in this region. None of the premises makes the conclusion impossible to be true.
E
uses a claim that presupposes the truth of its main conclusion as part of the justification for that conclusion
(E) describes circular reasoning. None of the premises assume the truth of the conclusion. The premises include comparison between sizes of apples today, and a claim about sizes of remains of certain apples. The conclusion is about whether those apples were cultivated.
Pankaj: But keep in mind that the ban would apply only to smoking in public places. People could still smoke all they want in private.
Speaker 1 Summary
Ana opposes the proposed smoking ban because she thinks it’s not the government’s business to prevent people from doing stuff that harms only themselves.
Speaker 2 Summary
Pankaj points out that the proposed ban would only apply in situations that expose other people to smoking. Smoking would still be allowed in private. The implicit point is that Ana’s libertarian principle isn’t a good reason for opposing the ban.
Objective
We’re looking for a point of disagreement. They disagree over whether the proposed smoking ban would prevent people from doing things that harm only themselves. Ana thinks it would. Pankaj thinks it wouldn’t.
A
it is the government’s business to prevent people from harming themselves
Pankaj doesn’t have an opinion. He doesn’t discuss whether the government should or should not protect people from hurting themselves.
B
government should be restrained by libertarian principles
Pankaj doesn’t have an opinion. He doesn’t discuss libertarian principles.
C
the proposed smoking ban is intended to prevent harm only to smokers themselves
This is a point of disagreement. Ana believes the ban is intended to prevent harm only to smokers themselves. This is why she opposes the ban. Pankaj disagrees, since it bans smoking in public (where others are present).
D
the proposed ban would prohibit smoking in public places
Ana has no opinion. She believes the ban prevents people from doing things that harm only themselves. But whether this ban applies in public and private or only in private is not clear from her statements.
E
there are cases in which government should attempt to regulate private behavior
Pankaj doesn’t have an opinion. He doesn’t discuss whether government should ever regulate anything.
Summarize Argument: Phenomenon-Hypothesis
The author concludes that a dislike of vegetables is sometimes caused by genetics. This is based on a study involving two large, divers groups of volunteers. Everyone in one group enjoyed eating vegetables, while everyone in the other group disliked vegetables. Everyone in the group that disliked vegetables had the XRV2G gene.
Identify and Describe Flaw
The author assumes that the group that liked vegetables did not all have the XRV2G gene. This is the basis of another assumption that the study revealed a correlation between not liking vegetables and having the gene. Then, the author makes another assumption that the explanation for this correlation is that the gene causes a dislike of vegetables.
A
It presumes that all human traits are genetically determined.
The argument concerns only the human trait of disliking vegetables. The author doesn’t make any assumptions about all other human traits.
B
It overlooks the possibility that the volunteers in one or both of the two groups may not have been representative of the human population as a whole in one or more respects.
The argument doesn’t generalize from the members of the study to the human population generally. The conclusion is just that a dislike of vegetables is sometimes genetically determined; those times could involve just members of the study.
C
It overlooks the possibility that even when one phenomenon always produces another phenomenon, the latter phenomenon may often be present when the former is absent.
The conclusion does not assert that a dislike of vegetables is only caused by genetics. The conclusion is merely asserting that a dislike of vegetables is sometimes caused by genetics. This acknowledges that such dislike can also be caused by other things besides genes.
D
It overlooks the possibility that even if a dislike of vegetables is genetically determined, it may be strongly influenced by genes other than the XRV2G gene.
This possibility doesn’t undermine the argument. If dislike of vegetables can also be caused by other genes, that supports the conclusion that a dislike of vegetables is at least sometimes genetically determined.
E
It takes for granted that the volunteers in the group that enjoyed eating vegetables did not also all have the XRV2G gene in common.
This must be assumed, because if it wasn’t true, the conclusion wouldn’t follow from the premises. If the group that liked vegetables also all had the XRV2G gene, then there’s no reason to think from the study that the XRV2G gene plays any role in dislike of vegetables.
Very similar to the weakness in this argument:
LSAT41-S1-Q12
Summary
The government will not pay for patients to take Antinfia until the manufacturer provides information about the drug’s cost-effectiveness. This information can only be obtained by performing massive clinical trials. The trials cannot be performed until the drug is in widespread circulation, which will happen only if the government pays for Antinfia.
Strongly Supported Conclusions
Government pays → provide detailed info → massive clinical trails → widespread circulation → government pays
This chain is circular, and the stimulus says the government is not paying. You can run the contrapositive back and draw any valid inference along the chain. (no widespread circulation, no clinical trials, no detailed info)
This chain is circular, and the stimulus says the government is not paying. You can run the contrapositive back and draw any valid inference along the chain. (no widespread circulation, no clinical trials, no detailed info)
A
The government health service never pays for any medicine unless that medicine has been shown to be cost-effective.
This is too broad to support. The stimulus is purely focused on Antinfia, not “any medicine”
B
Antinfia will never be in widespread circulation.
The stimulus says that the drug will be in wide circulation only if the government pays. The government is refusing to pay. Thus, it will never be in wide circulation.
C
If the government health service does not pay for Antinfia, then many patients will pay for Antinfia themselves.
The stimulus does not give any information about whether patients will pay out of pocket or not. You need to make some assumptions to make this work
D
The government health service should pay for patients to take Antinfia.
The stimulus does not say whether the government should/should not pay for Antinfia. It only explains what barriers the drug is facing to becoming widely available.
E
Antinfia is not cost-effective.
The stimulus does not say whether Antinfia is/is not cost-effective. The stimulus only notes that the drug company cannot yet provide information about its cost-effectiveness.
Summarize Argument: Counter-Position
The author concludes that no contemporary artists’ works enable lots of people to feel more aesthetically fulfilled than those people otherwise would be. (In other words, if the contemporary artists’ works never existed, there aren’t a lot of people who would be less fullfilled than they are right now.) This is based on the fact that there are already more great artworks in the world than any one person could appreciate in a lifetime, and those works can satisfy any preference.
Identify and Describe Flaw
The author overlooks the possibility many people might not be able to access as much artwork that is to their taste if certain contemporary artists’ works did not exist. That artwork might exist in the world, but merely being available in the world does not guarantee that everyone will be able to access it.
A
overlooks the possibility that not all contemporary artists believe that their works enable many people to feel more aesthetically fulfilled than they otherwise could
This isn’t overlooked, because the author states as a premise that “all” contemporary artists believe that their works enable many people to feel more aesthetically fulfilled than they otherwise could.
B
presumes, without providing justification, that most human beings are inclined to take the time to appreciate many great artworks
The argument concerns the level of aesthetic fulfillment that many people could have if contemporary artists’ works did not exist; whether people actually want to see art is a separate issue.
C
presumes, without providing justification, that the value of an artwork depends on the degree to which human beings appreciate it
The argument doesn’t concern the “value” of an artwork. It’s about whether contemporary artists allow many people to feel more fulfilled than those people otherwise could be. This is a separate issue from the worth or value of an artwork.
D
overlooks the possibility that the work of at least one contemporary artist is appreciated by many people whose access to the great majority of other artworks is severely restricted
This possibility shows that there might be some cont. artist who does bring more aesthetic fulfillment to many people than those people could otherwise have. If that artist weren’t around, many might not have access to art of the particular style/taste that the artist produced.
E
presumes, without providing justification, that the number and variety of great artworks already in the world affects the amount of aesthetic fulfillment derivable from any contemporary artwork
The argument doesn’t concern whether existing artwork “affects” (changes) the aesth. fulfillment people get from art. It’s about whether, if certain art didn’t exist, people would be able to replace the fulfillment from that art with existing art. Can people find a substitute?