June 2010 LSAT Section 4 Question 23

A species in which mutations frequently occur will develop new evolutionary adaptations in each generation. Since spe...

MARIO on March 24, 2016

Answer A To Confirm

Answer A is flawed as well by assuming a necessary condition will bring about the sufficient correct? It's just not flawed in the same pattern as the stimulus or the correct answer because it does not conclude the existence of a sufficient condition of a premise to conclude the sufficient of another, when it in fact only provides us with a necessary condition

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Mehran on March 27, 2016

@MARIO no (A) is a valid argument. The argument would be diagrammed as follows:

P: "In a stone wall that is properly built, every stone supports another stone."

PB ==> ESSAS
not ESSAS ==> not PB

P: "Since a wall's being sturdy depends upon its being properly built..."

S ==> PB
not PB ==> not S

C: "...only walls that are composed entirely of stones supporting other stones are sturdy."

S ==> ESSAS
not ESSAS ==> not S

This is a proper transitive inference, i.e. S ==> PB ==> ESSAS.

Hope that helps! Please let us know if you have any other questions.

anadeem321@hotmail.com on October 24, 2022

I do not understand...

In P: "In a stone wall that is properly built, every stone supports another stone."

"every" is a sufficient indicator

therefore for the premise it will be diagrammed as follow:

ESSAS ==>PB
not PB==> not ESSAS

afterwards

P: "Since a wall's being sturdy depends upon its being properly built..."

S ==> PB
not PB ==> not S

C: "...only walls that are composed entirely of stones supporting other stones are sturdy."

S ==> ESSAS
not ESSAS ==> not S

This is a NOT proper transitive inference since both premises has the necessary conditions in common just like answer choice A

anadeem321@hotmail.com on October 24, 2022

Just like stimulus***

Emil-Kunkin on October 26, 2022

Hi,

I think you may have the opening statement reversed. The sentence is saying that if a stone wall is built properly, then every stone supports another. This would be If PB -> Essa