Sections 4

LSAT 61 - Section 4 - Question 21

May 13, 2012

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LSAT 61 - Section 4 - Question 22

May 13, 2012

4 comments

LSAT 61 - Section 4 - Question 23

May 13, 2012

26 comments

LSAT 61 - Section 4 - Question 24

May 13, 2012

1 comment

LSAT 61 - Section 4 - Question 25

May 13, 2012

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LSAT 61 - Section 4 - Question 26

May 13, 2012

The first statement of the passage tells us, translated:
NOT educated population --> economically and politically weak

Taking the contrapositive, we get:
NOT economically and politically weak --> educated population

The next statement tells us, translated:
educated population --> commit to public education

Connect the two statements up and we get:
NOT economically and politically weak --> educated population --> commit to public education

From this, we are able to validly draw the conclusion that:
NOT economically and politically weak --> commit to public education

But, of course, the invalid conclusion actually drawn is:
commit to public education --> NOT economically and politically weak

The general form of this invalid argument is as follows:
A --> B --> C
__________
C --> A

Answer choice (B) exhibits the same form.

The first statement tells us that, translated:
incapable of empathy --> not good candidates

Contraposed, it says:
good candidates --> capable of empathy

The second statement tells us that, translated:
capable of empathy --> manipulate

Connect the two statements up and we get:
good candidates --> capable of empathy --> manipulate

From this, we are able to validly draw the conclusion that:
good candidates --> manipulate

But, of course, the invalid conclusion actually drawn is:
manipulate --> good candidates

As you can see, this argument, like the one in the passage, also takes the invalid form of:
A --> B --> C
__________
C --> A

10 comments

LSAT 143 - Section 4 - Question 20

May 13, 2012

21 comments

LSAT 143 - Section 4 - Question 21

May 13, 2012

In modern deep-diving marine mammals, such as whales, the outer shell of the bones is porous. This has the effect of making the bones light enough so that it is easy for the animals to swim back to the surface after a deep dive. The outer shell of the bones was also porous in the ichthyosaur, an extinct prehistoric marine reptile. We can conclude from this that ichthyosaurs were deep divers.

Summarize Argument

The author concludes that ichthyosaurs were deep divers. This is because ichthyosaurs share a feature with deep-diving mammals today: a porous outer bone shell. This feature is what helps deep-diving mammals surface after deep dives.

Notable Assumptions

The author assumes that the only function of the porous outer bone shell is to help animals surface after deep dives. If any given animal isn’t a deep diver, then it won’t have the porous outer bone shell feature.

A

Some deep-diving marine species must surface after dives but do not have bones with porous outer shells.

The author never says the porous outer bone shell is necessary for deep dives. It simply indicates that an animal is a deep-diver.

B

In most modern marine reptile species, the outer shell of the bones is not porous.

We have no idea if those reptiles are deep-divers.

C

In most modern and prehistoric marine reptile species that are not deep divers, the outer shell of the bones is porous.

Reptiles generally have porous outer bone shells despite not being deep divers. Since the ichthyosaur was a reptile, we can’t conclude if it was a deep diver.

D

In addition to the porous outer shells of their bones, whales have at least some characteristics suited to deep diving for which there is no clear evidence whether these were shared by ichthyosaurs.

We don’t need ichthyosaurs to have the exact same characteristics as whales. There are plenty of deep divers that aren’t whales.

E

There is evidence that the bones of ichthyosaurs would have been light enough to allow surfacing even if the outer shells were not porous.

This tells us that ichthyosaurs could’ve been deep divers even without the porous outer bone shells. We need to weaken the claim that ichthyosaurs were in fact deep divers.

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LSAT 143 - Section 4 - Question 22

May 13, 2012

Librarian: Some argue that the preservation grant we received should be used to restore our original copy of our town’s charter, since if the charter is not restored, it will soon deteriorate beyond repair. But this document, although sentimentally important, has no scholarly value. Copies are readily available. Since we are a research library and not a museum, the money would be better spent preserving documents that have significant scholarly value.

Summarize Argument: Counter-Position

Other people think that a preservation grant should be used to restore the original copy of our town’s charter. The author concludes that the money should instead be spent preserving other documents. This is because the town charter has no scholarly value, and we are a research library, which implies that we should care more about documents that have scholarly value.

Identify Argument Part

The referenced text is the reason that other people believe we should use the grant to restore the original copy of our town’s charter.

A

It is a claim that the librarian’s argument attempts to show to be false.

The author doesn’t disagree that the charter will deteriorate beyond repair if not restored. The author disagrees with the recommendation that we should restore the original version of this charter.

B

It is the conclusion of the argument that the librarian’s argument rejects.

The referenced text is not the conclusion that the author rejects. It’s the premise that other people use to support the conclusion that the author rejects.

C

It is a premise in an argument whose conclusion is rejected by the librarian’s argument.

This accurately describes the role. Other people use the fact the charter will soon deteriorate to support a recommendation that we should restore the charter. The author rejects this argument.

D

It is a premise used to support the librarian’s main conclusion.

The referenced text does not support the author’s conclusion. It supports other people’s conclusion, which the author rejects.

E

It is a claim whose truth is required by the librarian’s argument.

The referenced text is not required for the author’s conclusion. Even if the town charter wouldn’t deteriorate, it can still be true that the preservation grant would be better spent preserving other documents.

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LSAT 143 - Section 4 - Question 23

May 13, 2012

27 comments