PT62 S4 Q18 If there are sentient beings...

schyler.cox

OKAY WHAT IS THIS QUESTION????? I've looked it up on Manhattan's forum, cause they have most of the questions already written out, but I STILL don't understand it. This whole test was a beast to be honest...

I know this is a sufficient assumption question. So far, I have:

~SS
C --> IH
~IH --> ~C

--------------------------------
D --> IH

(SS = send spacecraft) (C = communicate) (IH = intelligent as humans) (D = determine existence)

How do we get to answer D, or I guess a better way to put it would be how do I figure out what the assumption is using the formal logic like JY does?

P.S. Sorry I'm needy tonight

inactive

Bumping this to the top!

For reference: http://7sage.com/lsat_explanations/lsat-62-section-4-question-18/

DumbHollywoodActor

@schyler.cox
I think you mean question 18. I just BR-ed this question (in anticipation of the BR Skype group this evening. You should join us!!!). This problem is a mess. It’s got embedded conditionals and DeMorgan’s Law too.

Conclusion: If there are sentient beings , we will not be able to determine it unless they're intelligent as humans. (SB+AD→ IAH)

Premise: We Will not be able to send spacecraft to those planets (/AS),

Premise: any sentient being on another planet capable of communicating are intelligent as we are (CC→IAH).

Analysis: /AS
CC→IAH
_______
SB+AD→ IAH

Gap: (SB+ AD→/AS + CC) If there are sentient beings AND we are able to determine it, then we’re not be able to send spacecraft to them AND any sentient being on another planet is capable of communicating With us.

ANALYSIS: The contrapositive (remember DeMorgan’s Law) of the gap is ( /CC or AS → /SB or /AD) . If any sentient being on another planet is NOT capable of communicating With us OR If we’re able to send spacecraft there, then there are NOT sentient beings outside of our solar system OR we are NOT able to determine this.

Taking the contrapositive and applying DeMorgan’s Law makes this gap much more manageable to fill. We only need one condition on either side of the conditional statement to fill the gap.

Elimination: (A) out of scope. (B) what the being would want is out of scope. (C) We don’t need to boost the premise with more discussion of intelligence. (D) looks good. (E) Again, intelligence isn’t part of the gap.

Selection: (D) works; “If a sentient being on another planet cannot communicate With us, then the only Way to detect its existence is by sending a spacecraft to its planet.” This is ANOTHER embedded conditional and it translates to /CC + AD -->AS. And the contrapositive (/CC + /AS→/AD), fills the gap and more.

What a mess!

Hopefully, you can see that because “Intelligence" isn’t part of the gap, (C) and (E) are out of the running. (A) and (B) clearly are out of the argument’s scope. So, during the actual test, you can feel very confident circling D.

DumbHollywoodActor

I’d love to have @c.janson35 weigh in on this bad boy