PT62.S2.Q15 - contemporary critics

mitrakhanom1mitrakhanom1 Member
edited December 2015 in Logical Reasoning 62 karma
I'm confused how to write the conditional logic for this. Can somebody please explain this? When I see how the video skipped over labeling the first sentence like a premise, I got confused why he then uses it in conditional logic (TMU---> IASC)? I also got confused with what to do with the third sentence. I thought its a conclusion because of the keywords thus, until I got to the last sentence. I understand how he got the conclusion as /TMU.

http://7sage.com/lsat_explanations/lsat-62-section-2-question-15/

Comments

  • Q.E.DQ.E.D Alum Member
    edited December 2015 556 karma
    I gotta drop a plug for predicate logic here. I find it highly appropriate in this case because it captures the recursive application of Smith's claim to Smith's knowledge of her own claim.

    ∀x∀y(xMy-->xCy)
    Anyone x knows anyone y's meaning (M) only if x knows y's circumstances (C).

    sMs-->sCs
    Substituting Smith for both x and y: Smith know's Smith's meaning only if Smith knows Smith's circumstances.

    ~sCs->~sMs
    Contrapositive of above

    ~sCs (MA)

    So ~sMs

    I realize it's unrealistic for someone to drop everything and pursue formal logic in the middle of LSAT prep, but it wouldn't take long to learn how bound variables work in formal systems, and I think it might be worth the clarity it brings.
  • mitrakhanom1mitrakhanom1 Member
    62 karma
    I haven't studied predicate logic. I'm still confused how to use this.
  • Accounts PlayableAccounts Playable Live Sage ⭐
    3107 karma
    Essentially, this argument is a contrapositive type argument, and we are looking for a sufficient assumption.

    Smith believes that true meaning understood--->Insight into social circumstances. The author then concedes that we are to assume that Smith's belief is correct (which means that his conditional statement is useful,and that we can apply it to Smith herself). The argument then concludes that Smith isn't aware of her own true meaning.

    What I we are looking for: If we conclude that someone doesn't understand true meaning (I think it's a fair assumption to say that not being aware of your own true meaning captures the idea that you don't understand your own true meaning), then saying that Smith doesn't have insight into her own social circumstance allows us to arrive at the correct conclusion. That's what answer choice B stays.

    Answer D is probably the hardest to eliminate. We actually don't care whether or not the theory itself lacks insight. The author assumes that Smith's theory holds and that we can use. Additionally, the author is applying Smith's theory to "her own words," so even if you don't catch the fact that the author isn't analyzing Smith theory, the fact that the application is to Smith only makes this answer choice not a sufficient assumption.

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