LSAT 120 - Section 4 - Question 02

February 21, 2014

Dr. Theresa Pagano, a biologist, has found that the checkerspot butterfly is becoming more prevalent in regions farther north than before and less prevalent in regions farther south. The northward shift of the butterflies is almost perfectly correlated with the northward shift of the warm zones in the global climate, and Dr. Pagano has therefore concluded that the changing climate is responsible for the northward movement of the butterflies.

Summarize Argument: Phenomenon-Hypothesis
Dr. Pagano hypothesizes that climate change has caused butterflies to move north. This is based on a correlation between the northern shift of butterflies and the northern shift of the climatic warm zone.

Notable Assumptions
Dr. Pagano assumes that butterflies will actively migrate towards warm zones. She also assumes that the butterflies in question had some reason for doing so, since she never mentions that their previous habitat was unsatisfactory.

A
Checkerspot butterfly colonies observed under laboratory conditions are critically affected by small temperature changes.
The butterflies are very sensitive to climate change. They thus expand their range north as northern climates become incrementally warmer.
B
Climate does not affect checkerspot butterflies themselves directly, but the plants they depend on thrive best in warm climates.
While the butterflies aren’t directly affected, their food source grows better in warmer climates. This explains why they’ve expanded their range north, where climates are warming.
C
Experimental evidence suggests that the checkerspot butterfly can adapt easily to a wide range of temperatures and geographic conditions.
This weakens the author’s argument. If the butterflies can adapt to many climates, then they’re not migrating north for the warm climate.
D
In recent years, abnormally low average temperatures have been correlated with a reduced checkerspot butterfly population.
This shows that butterflies are sensitive to temperature, which is necessary for the author’s argument.
E
Several studies have shown that several other species of butterfly closely related to the checkerspot butterfly survive only in warm climates.
These butterflies need warm climates. This explains why they’ve only expanded their range north once the climate has warmed.

13 comments

LSAT 120 - Section 4 - Question 03

February 21, 2014

Professor: The best users of a language are its great authors. However, these authors often use language in ways that are innovative and idiosyncratic, and are therefore less respectful of the strictures of proper usage than most of us are.

Summary

Great authors are the best users of a language. These authors use language in new and unique ways, and so use language in ways that conform less to proper usage rules than others.

Strongly Supported Conclusions

Conforming to rules of proper language usage is not necessary to be a great author.

Innovative and unique uses of language are inconsistent with complete adherence to the rules of proper language usage.

A
People who want to become great writers should not imitate great authors’ use of language.

Unsupported. The way great authors use language might contribute to the quality of their writing. So, there’s no support for a recommendation not to copy great authors’ use of writing.

B
Writers who do not observe proper language usage risk developing a peculiar or idiosyncratic style.

Unsupported. The vast majority of failures to observe proper language usage may involve standard, common errors. Although great writers often have a unique style, this doesn’t mean such style results from failure to observe proper language usage.

C
Those most talented at using a language are not as likely as most other people to observe proper language usage.

Strongly supported. The stimulus tells us that the best users of a language are great authors, who often use language in new and unique ways, which means they do not respect proper language usage as much as most other people.

D
People who use an innovative or idiosyncratic writing style often incur criticism of their language usage.

Unsupported. The stimulus doesn’t tell us whether new and unique writing styles incur criticism. The mere fact that such styles involve failure to observe proper language usage doesn’t imply that anyone criticizes the styles for the way they use language.

E
The standard for what constitutes proper language usage should be set by the best users of a language.

Unsupported. The stimulus doesn’t support any prescriptive claim about how standards “should” (or should not) be set.


11 comments

LSAT 120 - Section 4 - Question 04

February 21, 2014

The purpose of the physical sciences is to predict the order in which events will succeed one another. Human behavior, also, can sometimes be successfully predicted. However, even successful predictions of human behavior do not provide an understanding of it, for understanding a human action requires knowing its goal, even though such knowledge of goals either cannot or need not be obtained in the case of nonhuman behavior.

Summarize Argument
The argument concludes by saying that successful predictions of human behavior don’t necessarily mean that the behavior is understood. The argument provides the following conditional relationship:
Understanding human action→ Know its goal
The contrapositive of the relationship is:
/Know the goal of an action→ /Understand human action
When taken with the assumption that we don’t know the goal of an action when we predict it, we reach the conclusion that predicting human behavior does not come with an understanding of the behavior.

Identify Conclusion
The conclusion is that successfully predicting human behavior does not mean successfully understanding it: “Even successful predictions of human behavior do not provide an understanding of it.”

A
Successful predictions of human behavior do not constitute an understanding of that behavior.
This is the conclusion. Along with the assumption that we don’t know the goal of an action when we predict it, we come to the conclusion that successful predictions of behavior don’t necessarily mean understanding the behavior.
B
One cannot predict an instance of human behavior without an understanding of the agent’s purpose in engaging in that behavior.
/Understanding the agent’s purpose→/Predict the behavior
The contrapositive is:
Predict the behavior→Understand the agent’s purpose
This claim is a contradiction of the claims made in the argument, so it is not the conclusion.
C
In some cases, but not in others, understanding an event consists in the ability to predict the occurrence of that event.
This conclusion is about human behavior, so this claim about understanding and predicting events is irrelevant to the argument. Further, this claim about understanding events sometimes being related to predicting an event is not supported by the information in the argument.
D
The goal of the physical sciences is to predict the order in which events will occur.
The information about the purpose of the physical sciences serves as context for the argument, so this is not the main conclusion.
E
The methods used to predict human behavior must involve reference to the psychological states of human agents.
The argument does not mention the psychological states of human agents, so this claim is not supported by the argument.

2 comments

LSAT 120 - Section 4 - Question 05

February 21, 2014

Sickles found at one archaeological site had scratched blades, but those found at a second site did not. Since sickle blades always become scratched whenever they are used to harvest grain, this evidence shows that the sickles found at the first site were used to harvest grain, but the sickles found at the second site were not.

Summarize Argument: Phenomenon-Hypothesis
The phenomenon is that sickles found at one site had scratched blades, and sickles found at a second site did not. The author hypothesizes that the sickles from the first site were used to harvest grain, and the sickles from the second site were not. This is because sickle blades used to harvest grain always become scratched.

Notable Assumptions
The author assumes that because the sickle blades found at the first site were scratched, they must have been used to harvest grain. In extension, the author assumes there is no other function for sickle blades that could have resulted in the scratches. In other words, the author assumes that harvesting grain is necessary for scratched sickle blades.

A
Some sickles that have not yet been found at the first site do not have scratched blades.
This does not affect the argument. The author’s hypothesis is only an explanation for “this evidence” (i.e., the blades that were actually found)—blades that were there but not found are outside the scope of the argument.
B
The scratches on the blades of the sickles found at the first site resulted from something other than harvesting grain.
This weakens the argument. It attacks the assumption that because the sickle blades at the first site had scratches, the scratches must have been from harvesting grain. Remember: harvesting grain is sufficient for scratched sickle blades, not necessary.
C
Sickles at both sites had ritual uses whether or not those sickles were used to harvest grain.
This does not affect the argument. (C) does not imply anything about whether the sickle blades from the first site were used to harvest grain in addition to serving ritual purposes.
D
At the second site tools other than sickles were used to harvest grain.
This does not affect the argument. We already know that the sickle blades at the second site were not used to harvest grain. It is reasonable to assume that other tools were used for harvesting, as the sickle blades were not.
E
The sickles found at the first site were made by the same people who made the sickles found at the second site.
This does not affect the argument. The argument is concerned with the function of the sickle blades, not with who made them.

19 comments

LSAT 120 - Section 4 - Question 06

February 21, 2014

Pain perception depends only partly on physiology. During World War II a significantly lower percentage of injured soldiers requested morphine than did civilians recuperating from surgery. The soldier’s response to injury was relief, joy at being alive, even euphoria; to the civilians, surgery was a depressing, calamitous event. So it would seem that the meaning one attaches to a wound can affect the amount of pain one perceives.

Summarize Argument
Physiology is only part of pain perception. Why? The meaning one attaches to a wound can also affect pain perception. How do we know? A WWII study showed that civilians and soldiers attached different meanings to their pain, and civilians requested more pain medication.

Identify Argument Part
This is the conclusion of the argument. The study supports that there are psychological components to pain perception, which in turn supports that pain perception is only partly dependent on physiology.

A
It is an assumption on which the argument depends.
The claim is the argument - everything else supports it. It cannot be an assumption if it is the conclusion.
B
It undermines the argument’s main conclusion.
It does not undermine the conclusion - it is the conclusion. The rest of the stimulus is used to support the claim.
C
It summarizes a position that the argument is meant to discredit.
The argument is not discrediting this claim - it is supporting it. The rest of the stimulus acts as evidence.
D
It is information that the argument takes for granted.
The argument does not take this claim for granted - it supports it. There is evidence for why we should believe the claim.
E
It is the main conclusion of the argument.
This is accurate - it is the main argument in the stimulus. The rest of the argument acts as evidence to support it.

9 comments

LSAT 119 - Section 4 - Question 20

February 21, 2014

34 comments

LSAT 119 - Section 4 - Question 21

February 21, 2014

36 comments

LSAT 119 - Section 4 - Question 22

February 21, 2014

All highly successful salespersons are both well organized and self-motivated, characteristics absent from many salespersons who are not highly successful. Further, although only those who are highly successful are well known among their peers, no salespersons who are self-motivated regret their career choices.

Summary
The stimulus can be diagrammed as follows:

Notable Valid Inferences
Well known people don’t regret their career choices.

If someone is not well organized, then they are not well known.

If someone is not self motivated, then they are not well known.

A
No self-motivated salespersons who are not highly successful are well organized.
This could be false. We don’t know anything about the subset of salespersons who are both self motivated and not highly successful. We can’t say whether or not they are well organized.
B
All salespersons who are well organized but not highly successful are self-motivated.
This could be false. We don’t know anything about the group of salespersons who are both well organized and not highly successful.
C
No salespersons who are well known among their peers regret their career choices.
This must be true. This answer can be rewritten as “Well Known→ /Regret.” As shown in the diagram, by chaining the conditional claims, we see that not regretting career choices is a necessary condition of being well known.
D
All salespersons who are not well organized regret their career choices.
This could be false. “/WO→R” is not a valid inference that shows up on the diagram. It could be the case that some salesperson is not well organized and also does not regret their career choice.
E
All salespersons who do not regret their career choices are highly successful.
This could be false. (E) is an incorrect reversal of the conditional relationship. We know that all people who are highly successful do not regret their career choices. (HS→/R). (E) says “/R→HS.” This incorrectly flips the sufficient and necessary conditions.

23 comments

LSAT 119 - Section 4 - Question 24

February 21, 2014

Biologist: We know the following things about plant X. Specimens with fuzzy seeds always have long stems but never have white flowers. Specimens with curled leaves always have white flowers, and specimens with thorny seedpods always have curled leaves. A specimen of plant X in my garden has a long stem and curled leaves.

Summary

Specimens with fuzzy seeds have long stems.

Specimens with fuzzy seeds lack white flowers.

Specimens with curled leaves have white flowers.

Specimens with thorny seedpods have curled leaves.

The biologist’s plant has a long stem and curled leaves.

Very Strongly Supported Conclusions

The biologist’s specimen has white flowers.

The biologist’s specimen lacks fuzzy seeds.

A
It has white flowers and thorny seedpods.

Unsupported. We know the specimen has white flowers, but we don’t know if it has thorny seedpods. Careful with negations—“no curled leaves” is a sufficient condition for “no thorny seedpods”, but that doesn’t mean “curled leaves” is a sufficient condition for “thorny seedpods”!

B
It has white flowers but lacks thorny seedpods.

Unsupported. We know the specimen has white flowers, but we don’t know if it has thorny seedpods. Careful with negations—“no curled leaves” is a sufficient condition for “no thorny seedpods”, but “curled leaves” tells us nothing about whether a specimen has thorny seedpods!

C
It has white flowers but lacks fuzzy seeds.

Very strongly supported. As shown below, by chaining the conditional claims, we see that “no curled leaves” is a necessary condition of both “fuzzy seeds” and “no white flowers”. Having curled leaves, then, is a sufficient condition for “white flowers” and “no fuzzy seeds”!

D
It has fuzzy seeds and thorny seedpods.

Anti-supported. Because the specimen has curled leaves, we know that it doesn’t have fuzzy seeds. We can’t determine whether it has thorny seedpods—“no curled leaves” is a sufficient condition for “no thorny seedpods”, but “curled leaves” tells us nothing about thorny seedpods!

E
It lacks both white flowers and fuzzy seeds.

Anti-supported. Because the specimen has curled leaves, we know that it has white flowers. It is true that it doesn’t have fuzzy seeds.


17 comments

LSAT 119 - Section 4 - Question 25

February 21, 2014

Unquestionably, inventors of useful devices deserve credit for their ingenuity, but the engineers who help develop an invention get too little recognition. Although inventors sometimes serve as their own engineers, more often, engineers must translate an inventor’s insight into something workable and useful. Therefore, engineers also deserve credit for their contribution.

Summarize Argument
In addition to inventors, engineers deserve credit for their contribution to inventions. They don’t usually get enough recognition, even though engineers are tasked with turning an inventor’s insight into something tangible and useful.

Identify Argument Part
This part of the argument is a small concession. The argument does not apply in every case because sometimes inventors act as their own engineers, so they do get the credit they deserve. It qualifies the scope of the claim, showing that it applies in most, but not all, cases.

A
It separates the practical and theoretical aspects of the argument.
This statement does not separate the practical and theoretical, it just explains some cases where the argument does not apply. The argument does not really have practical/theoretical aspects to separate.
B
It indicates that the problem identified in the argument does not arise in every instance.
This accurately describes how this statement functions. It explains the situations in which the problem of recognition does not apply: when inventors serve as their own engineers.
C
It supports an earlier statement regarding what is at issue in the argument.
It doesn’t support what is at issue - or support anything. Instead, it shows exceptions to the issue.
D
It concedes that a distinction on which the argument relies is unclear.
While there is a concession occurring, it is not saying that the distinction between inventor and engineer is unclear. The distinction is clear, there are just cases where one individual acts as both.
E
It introduces an alternative solution to the problem the argument is addressing.
The author is not suggesting that inventors be their own engineers, they are suggesting that they should get the credit that is due to them.

6 comments

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