LSAT 74 - Section 1 - Question 17

January 10, 2015

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LSAT 142 - Section 1 - Question 15

January 10, 2015

Researcher: Salmonella bacteria are a major cause of illness in humans who consume poultry. Young chicks that underwent a new treatment exhibited a lower incidence of Salmonella infection than did untreated chicks, although one week after the treatment was administered the treated chicks had higher concentrations of a variety of bacteria than did untreated chicks.

"Surprising" Phenomenon

Why did the young chicks that were given the new treatment have higher concentrations of a variety of bacteria than untreated chicks, even though they had lower rates of Salmonella?

Objective

The correct answer will be a hypothesis explaining a key difference between Salmonella and the other variety of bacteria. This difference should explain why treated chicks have lower Salmonella rates but higher levels of the other bacteria, either by showing how the treatment impacts both or how the bacteria interact with each other.

A
The new treatment takes several weeks to administer.

The effects of the treatment remain, regardless of how long it takes to administer. We are concerned with the end result and need an explanation for why treated chicks have lower Salmonella rates but higher levels of the other bacteria after the treatment is administered.

B
Levels of Salmonella bacteria in young chicks are generally not high to begin with.

We are not concerned with the initial rates of Salmonella in young chicks. Instead, we are looking at the change in the rate of Salmonella and the other variety of bacteria after chicks receive treatment.

C
Most chicks develop resistance to many harmful bacteria by the time they reach adulthood.

Adult chickens' resistance to bacteria doesn’t tell us about bacteria levels in young chicks. Also, even if the chicks are resistant to many harmful bacteria, we still need to know why they have higher levels of this specific bacteria one week after the new treatment.

D
The untreated chicks experienced a higher incidence of illness from infection by bacteria other than Salmonella than did treated chicks.

The untreated chicks’ incidence of illness doesn’t explain why treated chicks have lower Salmonella rates but higher levels of other bacteria. Also, we don’t know that the “other bacteria” in (D) is the same as the “other bacteria” in the stimulus.

E
The bacteria found in the treated chicks were nonvirulent types whose growth is inhibited by Salmonella bacteria.

This explains why treated chicks have higher levels of the other bacteria: without Salmonella, which normally limits their growth, the other bacteria can increase. The treatment reduces Salmonella, allowing the other bacteria to increase among treated chicks.


11 comments

LSAT 142 - Section 1 - Question 16

January 10, 2015

Debater: As a pedagogical practice, lecturing embodies hierarchy, since the lecturer is superior to the student in mastery of the subject. But people learn best from peer interaction. Thus, the hierarchy in lecturing is a great weakness.

Respondent: By definition, all teaching and learning are hierarchical, for all teaching and learning must proceed from simple to complex. In teaching mathematics, for example, arithmetic must precede calculus. Thus, the hierarchy in lecturing is a strength.

Summarize Argument: Counter-Position
The respondent concludes that hierarchy in lecturing is a strength. He supports this by saying that all teaching and learning involve hierarchy since they move from simple to complex concepts. As an example, he notes that arithmetic must be taught before calculus.

Identify and Describe Flaw
This is the cookie-cutter flaw of equivocation, where the author uses a key term in different ways. The respondent uses "hierarchy" to refer to the order of concepts from simple to complex. But the debater used "hierarchy" to describe power dynamics between lecturers being above students.

Since the respondent applies "hierarchy" differently than the debater, he sidesteps the debater’s whole argument. Simple concepts may need to be taught before complex ones, but this doesn’t address whether those concepts should be taught by a peer or by an authority figure.

A
concedes one of the major assumptions on which the debater’s argument depends
By saying that all teaching is hierarchical, the respondent does concede that lecturing is hierarchical, but this is a premise, not a major assumption. Regardless, (A) isn’t a flaw in the respondent’s argument; he can concede a claim and still disagree with the conclusion.
B
takes for granted that teaching methods that are effective in mathematics are also effective in other academic disciplines
Like (E), the respondent doesn’t assume that moving from simple to complex concepts is effective in other academic disciplines; he explicitly states it. He says that “all teaching and learning must proceed from simple to complex,” and just uses math as an example.
C
fails to consider the possibility that some characteristics of lecturing other than hierarchy are weaknesses
The respondent is only addressing whether hierarchy is a weakness or a strength of lecturing. Any other potential weaknesses of lecturing are irrelevant.
D
applies a key concept to a different aspect of education than the aspect to which the debater applied it
The respondent uses "hierarchy" to refer to the difficulty of concepts, while the debater uses it to describe the power difference between teachers and students. The respondent never addresses whether the teacher-student hierarchy is a strength because he misapplies the term.
E
takes for granted that the conceptual structure of mathematics is sufficiently representative of the conceptual structure of at least some other academic disciplines
Like (B), the respondent doesn’t assume that moving from simple to complex concepts in math is representative of other disciplines; he explicitly states it. Regardless, he still never addresses whether the teacher-student hierarchy is a strength or a weakness.

15 comments

LSAT 142 - Section 1 - Question 17

January 10, 2015

How the pigment known as Han purple was synthesized by the ancient Chinese of the Qin and Han dynasties has puzzled scientists. The Chinese chemists employed the same chemical ingredients used for Han purple in the production of a common type of white glass during that period. Both were produced in processes that involved subjecting the mixtures to high heat and mixing in lead to decrease the melting temperature. Thus, Han purple was probably discovered by fortuitous accident during glass production.

Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that Han purple was probably discovered by accident during the production of glass. This is based on the fact that the same chemical ingredients are used for Han purple and a common type of white glass that was made during the period Han purple was made. In addition, both Han purple and this white glass were made using processes that involved high heat and mixing in lead.

Notable Assumptions
The author assumes there’s no more likely explanation for the origin of Han purple besides accidental discovery during the production of white glass.

A
Chemical analysis shows that most of the known fragments of both Han purple and the white glass were produced within a small geographical radius.
This strengthens by establishing at least that Han purple and white glass were produced near each other. If this were not true, the author’s hypothesis wouldn’t make sense. (A) isn’t a powerful strengthener, but it most strengthens compared to the other answers.
B
Han purple was used for luxury and ceremonial items, whereas the white glass was used to make certain household items.
The purposes of Han purple and white glass doesn’t reveal anything about how Han purple was discovered.
C
The technique used for producing Han purple was known to very few people during the Qin and Han dynasties.
This limits the number of people who knew how to make Han purple. But does this help show that Han purple was discovered during the production of white glass? We have no reason to think so.
D
The ingredients used in producing both Han purple and the white glass were easily obtainable during the Qin and Han dynasties.
How easy the ingredients were to obtain doesn’t shed any light on whether Han purple was discovered during the production of white glass.
E
The white glass is found in more surviving artifacts from the Qin and Han dynasties than Han purple is.
(E) suggests white glass might have been more widely used or more durable. But that doesn’t tell us anything about whether Han purple was discovered during the production of white glass.

72 comments

LSAT 74 - Section 1 - Question 12

January 10, 2015

1 comment

LSAT 74 - Section 1 - Question 13

January 10, 2015

7 comments

LSAT 74 - Section 1 - Question 14

January 10, 2015

1 comment

LSAT 142 - Section 1 - Question 12

January 10, 2015

Archaeologists are discovering a great deal about the Sals culture. For example, recent excavations have unearthed smelting furnaces and tools of smelted copper and bronze. There were distinct Sals words for copper and for bronze, but none for iron. Thus, the Sals did not smelt iron.

Summary
The author concludes that the Sals did not smelt iron. This is based on the fact that the Sals did not have any distinct words for iron.

Missing Connection
The premise establishes that Sals didn’t have distinct words for iron. Does that guarantee that the Sals did not smelt iron? No. What does lacking a distinct word for a thing have to do with smelting the thing? To make the argument valid, we want to form a link to get from the premise to the conclusion:
If the Sals didn’t have a distinct word for a thing, then the Sals did not smelt the thing.
Another way to phrase the relationship we’re looking for:
If the Sals smelted the thing, then they had a distinct word for the thing.

A
If a culture had a distinct word for a metal, then it smelted that metal.
(A) can be used to reach a conclusion that a culture DID smelt a metal. But we’re trying to prove that the Sals did NOT smelt a metal. (A) reverses what would have been a correct answer.
B
If a culture was unfamiliar with a metal, then it did not have a distinct word for that metal.
(B) allows us to reach a conclusion that a culture did not have a distinct word for a metal. But we’re trying to prove that a culture did not smelt a metal. (B) doesn’t establish that the Sals didn’t smelt a metal.
C
If a culture smelted copper and bronze, then it had distinct words for copper and bronze.
The conclusion is that the Sals did not smelt iron. (C) concerns only copper and bronze. It doesn’t establish that the Sals did not smelt iron.
D
If a culture did not smelt a metal, then it was unfamiliar with that metal.
We’re trying to prove that the Sals did not smelt metal. (D) tells us what we can conclude IF we start off knowing that a culture not smelt a metal. But (D) doesn’t allow us to reach the conclusion that a culture did not smelt a metal.
E
If a culture smelted a metal, then it had a distinct word for that metal.
We know that the Sals did not have a distinct word for iron. (E) asserts that having a distinct word for a metal was necessary in order for a culture to have smelted that metal. So (E), in connection with the premise, establishes that the Sals did not smelt iron.

14 comments

LSAT 142 - Section 1 - Question 13

January 10, 2015

7 comments

LSAT 142 - Section 1 - Question 14

January 10, 2015

Currently, no satellite orbiting Earth is at significant risk of colliding with other satellites or satellite fragments, but the risk of such a collision is likely to increase dramatically in the future. After all, once such a collision occurs, it will probably produce thousands of satellite fragments, each large enough to shatter other satellites. The resulting collisions will produce many more fragments, and so on, causing the space around Earth to become quite heavily cluttered with dangerous debris.

Summarize Argument
The author concludes that the risk of a collision between satellites is likely to increase in the future. This is because once a collision occurs, it will produce satellite fragments, and these fragments will lead to other collisions with satellites and produce more fragments. Eventually, the area around Earth will be cluttered with these satellite fragments. This is why the risk of a satellite colliding with another satellite or satellite fragment will go up in the future.

Identify Argument Part
The referenced text is the conclusion of the argument.

A
It is an unsupported claim that is used to provide support for the argument’s conclusion.
The referenced text has support, because it’s a conclusion.
B
It is an unsupported claim that is used to support another claim that in turn supports the argument’s conclusion.
The referenced text has support, because it’s a conclusion.
C
It is a claim for which the argument provides some support, and which in turn is used to support the argument’s conclusion.
The referenced claim is the conclusion of the argument. It doesn’t support any other claim.
D
It is a claim that serves as the argument’s conclusion.
This accurately describes the role of the referenced text. It’s a conclusion supported by the author’s prediction about the increased number of satellite fragments in the future.
E
It is a claim that provides nonessential background information for the argument’s conclusion.
The referenced text is the conclusion of the argument. It’s not just background information.

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