PT 42 LR diagramming question

gmreplay
Posts: 171
Joined: Wed May 13, 2009 6:47 pm

PT 42 LR diagramming question

Postby gmreplay » Thu Feb 04, 2010 1:24 pm

I got #22 on section 4 correct, but I'm having an issue understanding why the right answer matches well with the stimulus.

The stimulus is A->B, therefore B->~A. This I've confirmed.

A is the right answer, and reads as follows "Most scholars are not motivated by a desire to win prestigious academic prizes. Thus, some of those who want to win prestigious academic prizes are not scholars.

This I have diagrammed as A->~B, therefore B->~A, which (at least diagrammatically) is valid and different than the prompt.

Some guy named River diagrammed it on this other site, but I'm fairly certain he left the first "not" out of his scholar diagram.
http://www.lawschooldiscussion.org/stud ... msg5363162
What's the deal?

Cambridge LSAT
Posts: 270
Joined: Mon Aug 24, 2009 3:26 pm

Re: PT 42 LR diagramming question

Postby Cambridge LSAT » Thu Feb 04, 2010 1:57 pm

Here's the stimulus boiled down:
P: most As are not Bs
C: some Bs are not As

What about this situation?
100 are A
49 are both A and B
49 are B

Here's choice A:
P: most scholars are not motivated
C: some who are motivated are not scholars

gmreplay
Posts: 171
Joined: Wed May 13, 2009 6:47 pm

Re: PT 42 LR diagramming question

Postby gmreplay » Thu Feb 04, 2010 2:05 pm

Interesting. I was reading the "only a minority" part of the prompt as "Some of those who engage in political action do so out of a sense of social justice" when in reality it is "Most people who engage in political action do not do so out of sense of social justice". It's a shame that the vagaries of English allow such different interpretations to follow from it.

Cambridge LSAT comes through again! Thanks for being so helpful!




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