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NA vs. SA question stem

edited April 2020 in Logical Reasoning 414 karma

I just went thru PT7 S4 Q13 and came across a question stem that’s says “In order for the conclusion above to be properly drawn, which one of the following assumptions would have to be made?” The question type is regarded as SA.

I originally thought it was a NA question despite the “in order for the conclusion above to be properly drawn,” because of PT56 S2 Q20. This NA question stem reads “which one of the following principles must be assumed in order for the psychologist’s conclusion to be properly drawn?”

Those two sound sooooo similar to me. I am able to tell apart NA and SA most of the time, but these two are messing my head. Any insight would be very helpful!

Comments

  • 414 karma

    To add I actually think PT7 S4 Q13 could be an NA question. Would love to hear someone else’s thoughts.

  • EddieMEddieM Alum Member
    edited April 2020 279 karma

    I think you were right, and that PT7 S4 Q13 was indeed an R.A. question!

    Conclusion: The fact that the percentage of homes with smoke detectors has gone from 30% to 45% over the last ten years has not made early detection of house fires more likely.
    Support: Over half of domestic smoke detectors are inoperative.

    Flaw: Takes for granted that just because half of domestic smoke detectors are inoperative, an increase in the percentage of homes with smoke detectors has contributed nothing to early house fire detection. (Fails to consider that the proportion of detectors that are faulty may have been as high or higher ten years ago--in which case a rise in smoke detector use would indeed seem to help.)

    D, the correct answer, addresses the flaw exactly, stating it in its positive form: there was an increase in the detectors' defectiveness rate.

    I do not think that this answer would be sufficient to guarantee the conclusion. Given only that this 50% defectiveness rate is up from 10 years ago, we can't be sure that going from 30% of homes with detectors to 45% of homes with detectors was a useless shift for fire detection. To guarantee that, you'd have to have to show not only that the rate of defectiveness has increased, but that it has increased enough to offset the gains to be had from an additional 15% of homes getting detectors. Seems like that would require something with numbers that my mind can't comprehend lol.

    But I think you were right! D has to be necessary. Try the negation test: Given its opposite, "there has been no increase in the defectiveness rate of detectors," how could the current high rate of defectiveness ever show that increasing the proportion of homes with detectors is useless? That would be like saying, "Sure more people get vaccinated these days than 10 years ago, but the vaccine's success rate has plateaued over the past ten years. So there's clearly been no benefit to increasing the proportion of people who are vaccinated." No way!

    Possibly more important than all this junk ^^ though (sorry, it's helpful for my own studying to write this stuff out) is that you can tell from the stem that it's an R.A. It does say "properly drawn," but what it's asking is NOT which answer, if plugged in, would "allow the conclusion to be properly drawn." Rather, it's asking which answer MUST be true, if the conclusion is EVER to "be properly drawn" from those premises. This is tricky question wording, but your original instinct was definitely right.

  • Cant Get RightCant Get Right Yearly + Live Member Sage 🍌 7Sage Tutor
    27848 karma

    I'm pretty sure both of these are SA. I guess the second one is technically a PSA since it's a principle, but same thing for the most part.

  • 414 karma

    @EddieM said:
    I think you were right, and that PT7 S4 Q13 was indeed an R.A. question!

    Conclusion: The fact that the percentage of homes with smoke detectors has gone from 30% to 45% over the last ten years has not made early detection of house fires more likely.
    Support: Over half of domestic smoke detectors are inoperative.

    Flaw: Takes for granted that just because half of domestic smoke detectors are inoperative, an increase in the percentage of homes with smoke detectors has contributed nothing to early house fire detection. (Fails to consider that the proportion of detectors that are faulty may have been as high or higher ten years ago--in which case a rise in smoke detector use would indeed seem to help.)

    D, the correct answer, addresses the flaw exactly, stating it in its positive form: there was an increase in the detectors' defectiveness rate.

    I do not think that this answer would be sufficient to guarantee the conclusion. Given only that this 50% defectiveness rate is up from 10 years ago, we can't be sure that going from 30% of homes with detectors to 45% of homes with detectors was a useless shift for fire detection. To guarantee that, you'd have to have to show not only that the rate of defectiveness has increased, but that it has increased enough to offset the gains to be had from an additional 15% of homes getting detectors. Seems like that would require something with numbers that my mind can't comprehend lol.

    But I think you were right! D has to be necessary. Try the negation test: Given its opposite, "there has been no increase in the defectiveness rate of detectors," how could the current high rate of defectiveness ever show that increasing the proportion of homes with detectors is useless? That would be like saying, "Sure more people get vaccinated these days than 10 years ago, but the vaccine's success rate has plateaued over the past ten years. So there's clearly been no benefit to increasing the proportion of people who are vaccinated." No way!

    Possibly more important than all this junk ^^ though (sorry, it's helpful for my own studying to write this stuff out) is that you can tell from the stem that it's an R.A. It does say "properly drawn," but what it's asking is NOT which answer, if plugged in, would "allow the conclusion to be properly drawn." Rather, it's asking which answer MUST be true, if the conclusion is EVER to "be properly drawn" from those premises. This is tricky question wording, but your original instinct was definitely right.

    Thank you for the reply! Glad to have you agree with me!

  • 414 karma

    @"Cant Get Right" said:
    I'm pretty sure both of these are SA. I guess the second one is technically a PSA since it's a principle, but same thing for the most part.

    Could you tell me why?
    JY has no explanation on the first one.

    But the second one is definitely NA: https://7sage.com/lsat_explanations/lsat-56-section-2-question-20/

  • Jonathan WangJonathan Wang Yearly Sage
    edited April 2020 6867 karma

    They're both definitely necessary assumption questions.

    Don't let the presence of the phrase "properly drawn" fool you. The question is asking what is necessary (needed/must be) in order for you to get to a perfect conclusion. It never asks you to actually get there. Remember that in a sufficient assumption question, your task is to find the statement that, IF you had it, WOULD get you to a properly drawn conclusion. In other words, in an SA question, your task is to affirmatively prove that one of your answer choices gets you 100% to the final result. This question definitely does not ask that of you. Rather, it merely asks you to supply something that's needed/something that must be assumed to draw a valid conclusion. Even if you supply a million sufficient assumptions in response to this question, you haven't necessarily provided me something that I need, as the question so plainly asks.

    Think of it this way: if I told you "I need to eat at least one apple in order for my diet to be properly balanced", does that mean that me eating one apple is sufficient to balance my diet? Am I even asking you to determine the sufficiency of eating one apple? And what does the presence of the phrase "properly balanced" have to do with answering that question?

    Another example: "In order for our road trip to be properly executed, which of the following must be provided?". Suppose that the answer is "a car" - something I'm sure we can all agree is a good answer. By answering this way, are we saying that having the car is sufficient for the road trip to happen?

    In this case, the mention of a "properly drawn" conclusion is merely a reference to the argument's chances of being valid. The question only refers to it because it wants to make sure you know that you're supposed to be identifying what is necessary for you to continue down that "proper" path - i.e., I have to assume (X) to keep on striving toward perfection. If you reword the question to take out the buzzphrase "properly drawn" and instead replace it with an equivalent - something like "for the argument to proceed to a logical conclusion, which one of the following must be assumed" - the answer suddenly becomes crystal clear.

    Just so we're clear, this is also definitely not a case of necessary "taking precedence" or "superseding" sufficient. That's not how any of this works. It's a necessary assumption because it (1) definitively has the characteristics of a necessary assumption question, and (2) it is completely devoid of the characteristics of sufficient assumption question. If you looked at the phrase "properly drawn" and think it must be SA on that basis alone, then you might be overly relying on buzzwords and buzz-phrases to 'identify' your situation (pure pattern recognition), instead of using your theory knowledge properly to derive your understanding (flexible application of theoretical concept).

    And finally, all of this, while theoretically interesting, is largely a moot point since the LSAT has gotten very good about clearly delineating NA and SA in modern day. So rest assured that this particular problem probably won't rear its head very often, if ever again. Nevertheless, the lesson and thought process behind the analysis should remain.

  • Cant Get RightCant Get Right Yearly + Live Member Sage 🍌 7Sage Tutor
    27848 karma

    @"caffeine powered human" said:

    @"Cant Get Right" said:
    I'm pretty sure both of these are SA. I guess the second one is technically a PSA since it's a principle, but same thing for the most part.

    Could you tell me why?
    JY has no explanation on the first one.

    But the second one is definitely NA: https://7sage.com/lsat_explanations/lsat-56-section-2-question-20/

    I think this is a good lesson on the dangers of rushing, haha. If I'd bothered to explain in the first place, I'd've corrected my mistake. I feel foolish for having to say something so self-evident, but Jonathan's explanation is the correct one. My bad, and thanks @"Jonathan Wang" for the correction.

    While I partially suspect I may just be trying to spin an error into something positive, I still want to highlight the fact that careless reading leads to mistakes, no matter how good you get. I see people all the time making the false assumption that they understand what they've read just based on the fact that they've read it. Reading is insufficient. Understanding takes processing and reflection of the information we've read. When we stop thinking about what we're reading, we start making mistakes. High scorers aren't the ones who've transcended this: They're the ones who've embraced it.

  • 414 karma

    @"Jonathan Wang" said:
    They're both definitely necessary assumption questions.

    Don't let the presence of the phrase "properly drawn" fool you. The question is asking what is necessary (needed/must be) in order for you to get to a perfect conclusion. It never asks you to actually get there. Remember that in a sufficient assumption question, your task is to find the statement that, IF you had it, WOULD get you to a properly drawn conclusion. In other words, in an SA question, your task is to affirmatively prove that one of your answer choices gets you 100% to the final result. This question definitely does not ask that of you. Rather, it merely asks you to supply something that's needed/something that must be assumed to draw a valid conclusion. Even if you supply a million sufficient assumptions in response to this question, you haven't necessarily provided me something that I need, as the question so plainly asks.

    Think of it this way: if I told you "I need to eat at least one apple in order for my diet to be properly balanced", does that mean that me eating one apple is sufficient to balance my diet? Am I even asking you to determine the sufficiency of eating one apple? And what does the presence of the phrase "properly balanced" have to do with answering that question?

    Another example: "In order for our road trip to be properly executed, which of the following must be provided?". Suppose that the answer is "a car" - something I'm sure we can all agree is a good answer. By answering this way, are we saying that having the car is sufficient for the road trip to happen?

    In this case, the mention of a "properly drawn" conclusion is merely a reference to the argument's chances of being valid. The question only refers to it because it wants to make sure you know that you're supposed to be identifying what is necessary for you to continue down that "proper" path - i.e., I have to assume (X) to keep on striving toward perfection. If you reword the question to take out the buzzphrase "properly drawn" and instead replace it with an equivalent - something like "for the argument to proceed to a logical conclusion, which one of the following must be assumed" - the answer suddenly becomes crystal clear.

    Just so we're clear, this is also definitely not a case of necessary "taking precedence" or "superseding" sufficient. That's not how any of this works. It's a necessary assumption because it (1) definitively has the characteristics of a necessary assumption question, and (2) it is completely devoid of the characteristics of sufficient assumption question. If you looked at the phrase "properly drawn" and think it must be SA on that basis alone, then you might be overly relying on buzzwords and buzz-phrases to 'identify' your situation (pure pattern recognition), instead of using your theory knowledge properly to derive your understanding (flexible application of theoretical concept).

    And finally, all of this, while theoretically interesting, is largely a moot point since the LSAT has gotten very good about clearly delineating NA and SA in modern day. So rest assured that this particular problem probably won't rear its head very often, if ever again. Nevertheless, the lesson and thought process behind the analysis should remain.

    I appreciate your comment so so much! I will always give the notion of necessity the highest note before being fooled by properly drawn. These two q stem are definitely unrepresentative, but I really wanted a clear confirmation moving forward. Thanks again!

  • 414 karma

    @"Cant Get Right" said:

    @"caffeine powered human" said:

    @"Cant Get Right" said:
    I'm pretty sure both of these are SA. I guess the second one is technically a PSA since it's a principle, but same thing for the most part.

    Could you tell me why?
    JY has no explanation on the first one.

    But the second one is definitely NA: https://7sage.com/lsat_explanations/lsat-56-section-2-question-20/

    I think this is a good lesson on the dangers of rushing, haha. If I'd bothered to explain in the first place, I'd've corrected my mistake. I feel foolish for having to say something so self-evident, but Jonathan's explanation is the correct one. My bad, and thanks @"Jonathan Wang" for the correction.

    While I partially suspect I may just be trying to spin an error into something positive, I still want to highlight the fact that careless reading leads to mistakes, no matter how good you get. I see people all the time making the false assumption that they understand what they've read just based on the fact that they've read it. Reading is insufficient. Understanding takes processing and reflection of the information we've read. When we stop thinking about what we're reading, we start making mistakes. High scorers aren't the ones who've transcended this: They're the ones who've embraced it.

    Thanks for replying and clarifying! I’ll take comfort knowing that everyone makes a mistake.

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