PT39.S2.Q07 & 08 - thoughts that keep a person from falling asleep

harrismegan

http://7sage.com/lsat_explanations/lsat-39-section-2-question-07/
http://7sage.com/lsat_explanations/lsat-39-section-2-question-08/

Logical Reasoning, Section 2, Question 7 & 8.

I'm trying to solidify my understanding of NA... I don't understand it. I can read it 100 times, but when I'm given a question on the LSAT, I still don't get it. So, i've been trying to identify NA when I see it in other questions.

7. Conclusion: a person prevented from sleep by thoughts should count sheep
Why? Because sheep occupy both sides of the brain.

Is the necessary assumption here... the answer to question 7? That the thoughts of sheep would not keep the person awake?

Because... if that were true. If counting sheep DID keep the person awake, then it would ruin our argument.

Am I right?!

LSATisland

I don't have the text of the question in front of me. But, judging from your post, that answer seems correct. Your analysis also seems right. In order to advocate sheep-counting to induce sleep, it is necessary to assume that doing so would not keep the person awake.

blah170blah

Hi Megan,

You are exactly right.

Here is how I mapped out the stimulus:
P: Counting sheep occupies both left and right sides of the brain
P: Occupying both left and right sides of the brain excludes sleep-preventing thoughts
______
C: People who have problems falling asleep because of thoughts should count sheep

Like you said, the assumption that is crucial to this argument is that counting sheep excludes thoughts, where excluding thoughts then helps people fall asleep. However, if thinking of sheep kept the person awake, then that would mean that counting sheep actually doesn't excludes thoughts, which means that the necessary component of the argument falls apart.

Diagrammed out:
Fall asleep --> exclude thoughts

If counting sheep doesn't exclude thoughts, then thoughts are not excluded, meaning you can't fall asleep.

Does that make sense?

harrismegan

Yes I'm glad I reasoned it right!
I've been trying to drill it in my head. Sometimes when I'm driving I run through simple examples.


Like:
Conclusion: All cats are either brown or grey.
Why? Premise: because cats have pigment to produce brown or grey fur.

The necessary assumption here would be that cats do not have any other pigment aside from the two that would produce brown or grey fur.
Because, if cats did have pigment to produce another color, then all cats could not be either brown or grey.

I think I'm getting the hang of it . #itisthesmallvictories!