PT18.S2.Q02 - all cattle ranchers dislike long winters

harshbirbansal

http://7sage.com/lsat_explanations/lsat-18-section-2-question-02/
Could anyone explain why the answer is C- All lawyers are cattle ranchers and not A- Some lawyers are cattle ranchers.

c.janson35

To rephrase in lawgic:

CR-->/LLW-->/SRO
contrapositive: SRO-->LLW-->/CR

We are trying to prove the conclusion that SRO-->/L; because the sufficient side variable lines up right where we want it (SRO), we just want a /L variable somewhere in our conditional chain that allows us to transitively draw the conclusion. Luckily, just adding it to the end allows us to do so:

SRO-->LLW-->/CR-->/L

What was the relationship we just added? /CR-->/L, which is the contrapositive of C: L-->CR

A some statement could never allow us to infer any kind of new "all" relationship, which is what the question is asking us to prove, so that's why C is incorrect.