Sections 4

Sign up to star your favorites LSAT 132 - Section 4 - Question 19

May 13, 2012

Doctor: Medical researchers recently examined a large group of individuals who said that they had never experienced serious back pain. Half of the members of the group turned out to have bulging or slipped disks in their spines, conditions often blamed for serious back pain. Since these individuals with bulging or slipped disks evidently felt no pain from them, these conditions could not lead to serious back pain in people who do experience such pain.

Summarize Argument

The doctor concludes that bulging or slipped disks, which are often claimed as the causes of serious back pain, could not cause serious back pain. This is based on the observation that a significant number of individuals have bulging or slipped disks, but have never experienced serious back pain.

Identify and Describe Flaw

Because many people have bulging or slipped discs without serious back pain, the doctor concludes that these conditions cannot cause serious back pain. But just because these conditions don’t always cause serious back pain on their own, that doesn’t mean they can’t be among the causative factors of serious back pain.

A

A factor that need not be present in order for a certain effect to arise may nonetheless be sufficient to produce that effect.

The doctor isn’t making any claims about some factor that is sufficient, but not necessary, for an effect. Rather, the argument claims that slipped or bulging disks are not sufficient to cause serious back pain.

B

A factor that is not in itself sufficient to produce a certain effect may nonetheless be partly responsible for that effect in some instances.

The doctor concludes that, since bulging or slipped disks are not sufficient to produce serious back pain, they never cause serious back pain. This ignores that they could still be partly responsible for some instances of serious back pain, and thus still “causes.”

C

An effect that occurs in the absence of a particular phenomenon might not occur when that phenomenon is present.

The doctor doesn’t make any claims about an effect that occurs in the absence of some phenomenon. Rather, the doctor discusses how the phenomenon of a slipped or bulging disk is not always followed by the effect of back pain.

D

A characteristic found in half of a given sample of the population might not occur in half of the entire population.

The doctor’s argument doesn’t rely on applying sample data to the entire population. The fact that half the sample is observed to have slipped or bulging disks without serious back pain is enough to say that these conditions aren’t always sufficient to cause serious back pain.

E

A factor that does not bring about a certain effect may nonetheless be more likely to be present when the effect occurs than when the effect does not occur.

How likely bulging or slipped disks (the factor) are to accompany serious back pain (the effect) isn’t relevant to the argument. The doctor isn’t concerned with how often these two things co-occur, but with their causal relationship.

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Sign up to star your favorites LSAT 132 - Section 4 - Question 20

May 13, 2012

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Sign up to star your favorites LSAT 132 - Section 4 - Question 21

May 13, 2012

It is virtually certain that the government contract for building the new highway will be awarded to either Phoenix Contracting or Cartwright Company. I have just learned that the government has decided not to award the contract to Cartwright Company. It is therefore almost inevitable that Phoenix Contracting will be awarded the contract.

Summarize Argument

The author concludes that Phoenix Contracting will almost certainly get the government contract for the new highway. He supports this by noting that the contract was expected to go to either Phoenix Contracting or Cartwright Company, and the government has decided not to award it to Cartwright Company.

Describe Method of Reasoning

The author draws his conclusion that Phoenix Contracting will very likely get the government contract by using the process of elimination. He notes that the contract was likely going to go to either Phoenix Contracting or Cartwright Company. Then, by claiming that Cartwright Company has been ruled out as a possibility, the author concludes that Phoenix Contracting will almost certainly get the contract.

A

concluding that it is extremely likely that an event will occur by ruling out the only probable alternative

The author concludes that it is extremely like that an event (Phoenix Contracting getting the government contract) will occur by ruling out the only probable alternative (Cartwright Company getting the government contract).

B

inferring, from a claim that one of two possible events will occur, that the other event will not occur

Actually, the author infers, from a claim that one event will not occur, that another event will occur. His claim is about an event not occurring, while his conclusion is about an event occurring. (B) reverses these.

C

refuting a claim that a particular event is inevitable by establishing the possibility of an alternative event

The author doesn’t refute a claim that a particular event is inevitable. Rather, he concludes that a particular event is almost inevitable. Also, he eliminates, rather than establishes, the possibility of an alternative event.

D

predicting a future event on the basis of an established pattern of past events

The author does predict a future event, but he does so by ruling out the only probable alternative, not on the basis of an established pattern of events.

E

inferring a claim about the probability of a particular event from a general statistical statement

By concluding that Phoenix Contracting will almost inevitably get the government contract, the author does infer a claim about the probability of a particular event. But he does this by eliminating the only probable alternative, not based on a general statistical statement.

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Sign up to star your favorites LSAT 132 - Section 4 - Question 22

May 13, 2012

Researchers have found that children in large families—particularly the younger siblings—generally have fewer allergies than children in small families do. They hypothesize that exposure to germs during infancy makes people less likely to develop allergies.

Summarize Argument: Phenomenon-Hypothesis

Researchers hypothesize that being exposed to germs during infancy reduces the chance people develop allergies. Their evidence is the fact that children in large families have fewer allergies than children in small families.

Notable Assumptions

The researchers assume that being in a large family generally exposes children to more germs than being in a small family.

A

In countries where the average number of children per family has decreased over the last century, the incidence of allergies has increased.

We need to compare between small and large families where all else is equal. We have no idea what environmental factors relating to allergies were like 100 years ago. Those factors could potentially explain the difference in allergies better than family size.

B

Children in small families generally eat more kinds of very allergenic foods than children in large families do.

This weakens the author’s argument. Exposure to germs isn’t what causes the difference in allergies between children in small and large families. Instead, diet causes that difference.

C

Some allergies are life threatening, while many diseases caused by germs produce only temporary discomfort.

We don’t care about the consequences of allergies and germs. We’re simply trying to strengthen the connection between germ exposure and developing allergies.

D

Children whose parents have allergies have an above-average likelihood of developing allergies themselves.

Irrelevant. This suggests allergies may be hereditary or environmental, given that children may grow up how their parents do. We’re trying to strengthen the connection between germ exposure and developing allergies.

E

Children from small families who entered day care before age one were less likely to develop allergies than children from small families who entered day care later.

Children who were exposed to other children at a young age were less likely to develop allergies than children who weren’t exposed to other children until later. This strengthens the author’s causal claim about germ exposure (from other children) and developing allergies.

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