Conditional & its Contrapositive in Limited Options?!?
Posted: Tue Sep 28, 2010 1:07 pm
Okay, so the LSAT Blog's explanation for Game 2 of PT60 sets up limited options based on the rule If M is before P, then H is before G. It makes 2 diagrams:
"One with the conditional rule of: M before P ---> H before G
Another with its contrapositive: G before H ---> P before M"
However, when I tried to set up limited options in PT52 game 4 based on this same idea - creating two main diagrams, one of the conditional in rule 3 and one of its contrapositive (even though the last rule was the basis for a much clearer [and the valid] limited options), this gave me more than one feasible answer for question 19 and question 20's "must be true" questions.
Rule 3 was: F...M ---> L...H
H....L ---> M...F
So I made one diagram with F before M and another with H before L.
Before reading the explanation to game 2 in the LSAT blog, I would have never created limited options based off of a conditional and its contrapositive (just when thinking about it intuitively, it does not make sense because those aren't the only 2 possibilities...L could come before H in other situations that don't have F before M, etc.) but I can't articulate neatly why to myself - can someone actually explain why not?
And why was it okay to do so in the LSAT Blog for game 2 (or was that not okay)? Here is a link to that: http://lsatblog.blogspot.com/2010/07/ls ... ptest.html
thanks a lot!
"One with the conditional rule of: M before P ---> H before G
Another with its contrapositive: G before H ---> P before M"
However, when I tried to set up limited options in PT52 game 4 based on this same idea - creating two main diagrams, one of the conditional in rule 3 and one of its contrapositive (even though the last rule was the basis for a much clearer [and the valid] limited options), this gave me more than one feasible answer for question 19 and question 20's "must be true" questions.
Rule 3 was: F...M ---> L...H
H....L ---> M...F
So I made one diagram with F before M and another with H before L.
Before reading the explanation to game 2 in the LSAT blog, I would have never created limited options based off of a conditional and its contrapositive (just when thinking about it intuitively, it does not make sense because those aren't the only 2 possibilities...L could come before H in other situations that don't have F before M, etc.) but I can't articulate neatly why to myself - can someone actually explain why not?
And why was it okay to do so in the LSAT Blog for game 2 (or was that not okay)? Here is a link to that: http://lsatblog.blogspot.com/2010/07/ls ... ptest.html
thanks a lot!