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SA and NA questions

jjoushlynjjoushlyn Alum Member
edited May 2018 in Logical Reasoning 198 karma

Hey 7sagers!

I was just wondering if anyone had any tips on how to really understand sufficient and necessary assumption questions . I get what they are supposed to do but I can’t seem to seem the arguments as valid with the correct answer choice for example :the steps I take with the sufficient assumptions is
1.read the question stem
2. Find the con. And premises
3. Try to find the flaw in between the premises and con.
4. Then look for what I think it is in the answer choice .

I’m not sure if this is the best way or not especially for necessary assumption . Are there any other ways I can think about this ? With necessary assumptions I follow all steps except I am not confident when going down to the answer choices .
I’m wondering how do I look at this differently ? Should I take an answer choice one by one with the other premises and see if it sounds correct ? I know it’s supposed to fill the gap but I guess I’m not seeing it fully.

Thanks !

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Comments

  • NovLSAT2019NovLSAT2019 Alum Member
    620 karma

    Reviewing the lessons from valid forms of argument can help immensely with the SA questions. Since SA asks for validity, whatever answer choice you decide to interject back into the stimulus needs to make the conclusion valid. If the notes I have from the lessons are correct, it’s usually missing a conditional statement for the conclusion to be valid.

  • btate87btate87 Alum Member
    edited May 2018 782 karma

    A few thoughts that might help you study the difference between the two

    Ask yourself...
    SA: If this answer is true, is the conclusion definitely true? (Can this argument lose with this?)
    NA: If this answer is not true, does it undermine the argument? (Can this argument win without this?)

    Qualities:
    SA: Often stronger
    NA: Often weaker/more subtle

    Practice:
    What helped me most for SA questions was brainstorming, without looking at the answers, 3-5 ideas that were sufficient. Think outside the box on these. Go above and beyond.

    Stolen from a Thinking LSAT episode I just listened to:
    If it costs $10 to get into a party
    $5 is necessary to get in but not sufficient to get in
    $10 is sufficient and necessary to get in
    $20 is sufficient but not necessary to get in

  • sunflowersandlawsunflowersandlaw Alum Member
    360 karma

    I've always thought of it as
    -For sufficient assumptions, you have to find the answer that makes the argument sufficient or "good enough". It's always a gap in the argument you're looking for. Something isn't completely thought out until you find the answer that's sufficient enough to prove the argument right.
    -for the Necessary assumptions - look for the answer that's necessary to prove the argument correct. It's not a gap you're looking for, but moreso an answer that if negated, would make the entire argument wrong. It kind of secures the answer.

  • AshleighKAshleighK Alum Member
    786 karma

    Hey! I haven't reached the NA lesson yet, but as far as SA goes I try to think of it like this:
    - I have the premise and the conclusion
    - There is a gap in this argument because the correct answer choice will bridge this gap

    On a scale of validity
    MSS is the lowest bound, PSA is in the middle, and SA is in the highest bound. In other words, what answer will make the conclusion true? Or make the argument valid 100%?

    A trick I do, is if I'm stuck between two contenders I'll follow this formula:
    Given premise + answer choice = Conclusion
    Is this 100%? Will this answer bridge the gap?

    If yes, there's your answer!

    Hope this helps :)

  • jjoushlynjjoushlyn Alum Member
    198 karma

    Thanks everyone ! This helps sooo much ! I hearing it in different ways helps !

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