What do necessary assumptions do to an argument's flaw?

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• 6 Likes

  Ohnoeshalpme Alum Member ⭐

  January 2019 2531 karma

  For NA questions, you shouldn't be pre-phrasing because NAs can be virtually infinite. In general, it is useful to understand the flaws in an argument because they can give you an idea of what to look for in the answer choices. But this process is often misleading and can be a major time sink. I would recommend that you allow the answer choices guide you through for NA questions. With practice, the correct NA will pop out to you when you read it.
• 3 Likes

  Alex Alum Member ⭐

  January 2019 23929 karma

  @Shrilaraune said:
  Hi there!
  So I'm still trying to answer this question and could use some help! Lots of different sources, including 7sager and the Trainer, suggest I find the flaw in the argument if I can, before considering answer choices. The question I've never been able to answer is this: Why? What does a correct answer choice in an NA question do to that flaw? With SA questions, the correct answer choice makes the flaw disappear. But with an NA, I don't have an answer. Any help would be amazing! I'm taking the Jan Lsat next week and I'm trying to tie up loose ends.

  Hi there!

  So with NA if you can find the flaw, you can see where an assumption was made. Assuming/overlooking something is a flaw!

  As @Ohnoeshalpme said above, knowing this can give you an idea of what you’re looking for.

  Although, I disagree that you shouldn’t be prephrasing on NA questions. Some are really amenable to prephrasing. I can actually prephrase for most NA questions. However, there definitely are some that are super tricky and hard to see. Because I’ve trained myself to preprephrase I’m more aware when I come across these and then I’ll let the answer choices guide me. It’s just always important to make sure you understand the argument to such a degree that you’ll know the correct answer when you see it.

  But I think to just always let the answer choices guide you would be a mistake. For one, if you have a prephrase you can go into “hunt mode” and find the answer with more confidence/less time. Second, the test writers are very good at making trap answers sound correct. So anytime you’re letting the answer choices guide you, you’re taking on that additional risk.

  Hope this helps!
• 1 Like

  DivineRaze Alum Member

  January 2019 556 karma

  @Shrilaraune You should definitely prephrase NA questions. The assumptions are easy to figure out if you pay attention to the arguments reasoning.
• 3 Likes

  redshift Alum Member

  January 2019 261 karma

  The necessary assumption TAKES CARE of the flaw in the reasoning. So let's say that our argument is this. Rattlesnakes grow sections on their tales each time they molt. Therefore, I can know the age of a rattlesnake by counting its sections.

  What's the flaw here? Well, we're assuming that rattlesnakes molt at an even pace. But this might not be the case. It could be the case that rattlesnakes molting patterns are extremely variable. If that's true, then we can by no means count the age of a rattlesnake just by counting its sections.

  If this argument is valid, then it must be the case that that flaw isn't happening. That is, it must be the case that rattlesnakes' molting patterns are NOT variable. That's the necessary assumption. On this particular question, the correct answer is: rattlesnakes molt as often when food is scarce as they do when food is plentiful. Or, in other words, rattlesnakes do not vary their molting patterns according to food scarcity.

  Note that this isn't a sufficient assumption. Knowing this does not allow us to conclude that we can know the age of a rattlesnake by counting its sections, because it could still be the case that rattlesnakes vary their molting patterns according to something else, like weather. That being said, it's a necessary assumption. It must be correct if the argument is valid. We know this because if we negate it, then we get: rattlesnakes vary their molting patterns according to food scarcity. If that's true, then the conclusion is destroyed.

  To sum, necessary assumptions most definitely have to do with flaws in reasoning. If you know what's wrong with an argument (the flaw), and you're asked to find the necessary assumption, then a correct answer would be one that blocks that flaw from happening. The flaw must not be happening if the argument is valid. That is a necessary consequence of an argument being valid, that a particular flaw isn't happening, and that's why we call those necessary assumptions.
• Shrilaraune Alum Member

  January 2019 169 karma

  @Ohnoeshalpme said:
  For NA questions, you shouldn't be pre-phrasing because NAs can be virtually infinite. In general, it is useful to understand the flaws in an argument because they can give you an idea of what to look for in the answer choices. But this process is often misleading and can be a major time sink. I would recommend that you allow the answer choices guide you through for NA questions. With practice, the correct NA will pop out to you when you read it.

  Hey!
  Thanks for stopping by! This is actually something I just heard for the first time yesterday! I'm actually really curious about how it works so I'd love it if you could explain your process? Maybe tell me some of the key triggers you see that make you go, "Ah-hah!"
• Shrilaraune Alum Member

  January 2019 169 karma

  @Alex said:

  @Shrilaraune said:
  Hi there!
  So I'm still trying to answer this question and could use some help! Lots of different sources, including 7sager and the Trainer, suggest I find the flaw in the argument if I can, before considering answer choices. The question I've never been able to answer is this: Why? What does a correct answer choice in an NA question do to that flaw? With SA questions, the correct answer choice makes the flaw disappear. But with an NA, I don't have an answer. Any help would be amazing! I'm taking the Jan Lsat next week and I'm trying to tie up loose ends.

  Hi there!

  So with NA if you can find the flaw, you can see where an assumption was made. Assuming/overlooking something is a flaw!

  As @Ohnoeshalpme said above, knowing this can give you an idea of what you’re looking for.

  Although, I disagree that you shouldn’t be prephrasing on NA questions. Some are really amenable to prephrasing. I can actually prephrase for most NA questions. However, there definitely are some that are super tricky and hard to see. Because I’ve trained myself to preprephrase I’m more aware when I come across these and then I’ll let the answer choices guide me. It’s just always important to make sure you understand the argument to such a degree that you’ll know the correct answer when you see it.

  But I think to just always let the answer choices guide you would be a mistake. For one, if you have a prephrase you can go into “hunt mode” and find the answer with more confidence/less time. Second, the test writers are very good at making trap answers sound correct. So anytime you’re letting the answer choices guide you, you’re taking on that additional risk.

  Hope this helps!

  Ooooh. I love an integrated approach. Thank you for the heads up! I'll try to integrate once I understand @Ohnoeshalpme and @"Cant Get Right"'s approach better
• Shrilaraune Alum Member

  January 2019 169 karma

  @DivineRaze said:
  @Shrilaraune You should definitely prephrase NA questions. The assumptions are easy to figure out if you pay attention to the arguments reasoning.

  I wholeheartedly agree. I'm actually really good at figuring out assumptions--thanks to the trainer (credit where credit is due!). That's why I'm so good at flaw questions. I'm really good at SA questions because I know what I'm supposed to do with the flaw once I've found it (or what the correct AC is supposed to do to the flaw I find)
• Shrilaraune Alum Member

  January 2019 edited January 2019 169 karma

  @redshift said:
  The necessary assumption TAKES CARE of the flaw in the reasoning. So let's say that our argument is this. Rattlesnakes grow sections on their tales each time they molt. Therefore, I can know the age of a rattlesnake by counting its sections.

  What's the flaw here? Well, we're assuming that rattlesnakes molt at an even pace. But this might not be the case. It could be the case that rattlesnakes molting patterns are extremely variable. If that's true, then we can by no means count the age of a rattlesnake just by counting its sections.

  If this argument is valid, then it must be the case that that flaw isn't happening. That is, it must be the case that rattlesnakes' molting patterns are NOT variable. That's the necessary assumption. On this particular question, the correct answer is: rattlesnakes molt as often when food is scarce as they do when food is plentiful. Or, in other words, rattlesnakes do not vary their molting patterns according to food scarcity.

  Note that this isn't a sufficient assumption. Knowing this does not allow us to conclude that we can know the age of a rattlesnake by counting its sections, because it could still be the case that rattlesnakes vary their molting patterns according to something else, like weather. That being said, it's a necessary assumption. It must be correct if the argument is valid. We know this because if we negate it, then we get: rattlesnakes vary their molting patterns according to food scarcity. If that's true, then the conclusion is destroyed.

  To sum, necessary assumptions most definitely have to do with flaws in reasoning. If you know what's wrong with an argument (the flaw), and you're asked to find the necessary assumption, then a correct answer would be one that blocks that flaw from happening. The flaw must not be happening if the argument is valid. That is a necessary consequence of an argument being valid, that a particular flaw isn't happening, and that's why we call those necessary assumptions.

  I'm trying to find out a way to star your post. Honor on you, honor on your house, honor on your cow. I knew there had to be a way to leverage the my flaw finding skills from the trainer with this question type. I just couldn't figure out what it was.

  Have you read the trainer? Can I ask you more questions?

  For posterity:
  An NA, as you learn in the 7sage CC is an assumption that must be true if the argument has a chance at being valid. You need to find out what the author was thinking, but didin't say. The easiest way, in my opinion, to do this is to find the conclusion, find the premises, and then ask yourself what the author is taking for granted/failing to consider. The answer to that question is an assumption. From there--as per @redshift 's brilliant deductions--you look for the answer that blocks this flaw; either by literally blocking it, or by lightly bridging the elements in the flaw to the rest of the argument. This is why NAs are so often mistaken with SAs. Both take care of the argument. The key is to realizing the different ways in which they do so. SA questions allow the conclusion to be drawn. The NA often does not as there are many, many NAs

  I am still interested in learning about how to let the answers guide you, because I'm aware that on trickier NA questions, the flaw you find likely won't be the one they utilize. And so having a plan 2 for when my prephrase isn't in the answer choices is key to my breaking 170 on test day.
• Shrilaraune Alum Member

  January 2019 169 karma

  @Shrilaraune said:

  @redshift said:
  The necessary assumption TAKES CARE of the flaw in the reasoning. So let's say that our argument is this. Rattlesnakes grow sections on their tales each time they molt. Therefore, I can know the age of a rattlesnake by counting its sections.

  What's the flaw here? Well, we're assuming that rattlesnakes molt at an even pace. But this might not be the case. It could be the case that rattlesnakes molting patterns are extremely variable. If that's true, then we can by no means count the age of a rattlesnake just by counting its sections.

  If this argument is valid, then it must be the case that that flaw isn't happening. That is, it must be the case that rattlesnakes' molting patterns are NOT variable. That's the necessary assumption. On this particular question, the correct answer is: rattlesnakes molt as often when food is scarce as they do when food is plentiful. Or, in other words, rattlesnakes do not vary their molting patterns according to food scarcity.

  Note that this isn't a sufficient assumption. Knowing this does not allow us to conclude that we can know the age of a rattlesnake by counting its sections, because it could still be the case that rattlesnakes vary their molting patterns according to something else, like weather. That being said, it's a necessary assumption. It must be correct if the argument is valid. We know this because if we negate it, then we get: rattlesnakes vary their molting patterns according to food scarcity. If that's true, then the conclusion is destroyed.

  To sum, necessary assumptions most definitely have to do with flaws in reasoning. If you know what's wrong with an argument (the flaw), and you're asked to find the necessary assumption, then a correct answer would be one that blocks that flaw from happening. The flaw must not be happening if the argument is valid. That is a necessary consequence of an argument being valid, that a particular flaw isn't happening, and that's why we call those necessary assumptions.

  I'm trying to find out a way to star your post. Honor on you, honor on your house, honor on your cow. I knew there had to be a way to leverage the my flaw finding skills from the trainer with this question type. I just couldn't figure out what it was.

  Have you read the trainer? Can I ask you more questions?

  For posterity:
  An NA, as you learn in the 7sage CC is an assumption that must be true if the argument has a chance at being valid. You need to find out what the author was thinking, but didin't say. The easiest way, in my opinion, to do this is to find the conclusion, find the premises, and then ask yourself what the author is taking for granted/failing to consider. The answer to that question is an assumption. From there--as per @redshift 's brilliant deductions--you look for the answer that blocks this flaw; either by literally blocking it, or by lightly bridging the elements in the flaw to the rest of the argument. This is why NAs are so often mistaken with SAs. Both take care of the argument. The key is to realizing the different ways in which they do so. SA questions allow the conclusion to be drawn. The NA often does not as there are many, many NAs

  Quick Note:
  I am still interested in learning about how to let the answers guide you, because I'm aware that on trickier NA questions, the flaw you find likely won't be the one they utilize. And so having a plan 2 for when my prephrase isn't in the answer choices is key to my breaking 170 on test day.
• 1 Like

  Bamboosprout Alum Member

  January 2019 edited January 2019 1694 karma

  IMO, NA don't have any direct relationship with the flaw. It may or may not fix it, or even need to address it.
  It's good to have an idea of what the flaw is, but recognizing the flaw is not the same thing as prephrasing a flaw. Definitely don't pre-phrase, or if you do, don't put too much weight into that prephrase. Especially for trickier questions, the trap answer is usually what you're prephrasing, except with one word changed. If you want to be 170+, don't prephrase NA, and just focus on the "gap" or flaw.
  Ok, so I said NA's don't have anything to direct relationship with the flaw, yet I focus on finding the flaw. Why? Here's my approach - first, I see if something must be true, as if it were a MBT question. Then, I negate the answer choices that I didn't eliminate to see if any of the negated answer choices "illustrates" the flaw. This is because, when negated, a NA should "become" the flaw. That's the definition of a NA, right? It means that, without it, the argument would be flawed, So although NA has no direct relationship with the flaw, once it is negated, it IS the flaw (or at least, one of many). This is demonstrated by the example in @redshift 's comment.
  So knowing the flaw is key for NA, because the negation of an NA "is" the flaw. So I hope this helps you see why knowing the flaw is so important.
• Shrilaraune Alum Member

  January 2019 169 karma

  @Bamboosprout said:
  IMO, NA don't have any direct relationship with the flaw. It may or may not fix it, or even need to address it.
  It's good to have an idea of what the flaw is, but recognizing the flaw is not the same thing as prephrasing a flaw. Definitely don't pre-phrase, or if you do, don't put too much weight into that prephrase. Especially for trickier questions, the trap answer is usually what you're prephrasing, except with one word changed. If you want to be 170+, don't prephrase NA, and just focus on the "gap" or flaw.
  Ok, so I said NA's don't have anything to direct relationship with the flaw, yet I focus on finding the flaw. Why? Here's my approach - first, I see if something must be true, as if it were a MBT question. Then, I negate the answer choices that I didn't eliminate to see if any of the negated answer choices "illustrates" the flaw. This is because, when negated, a NA should "become" the flaw. That's the definition of a NA, right? It means that, without it, the argument would be flawed, So although NA has no direct relationship with the flaw, once it is negated, it IS the flaw (or at least, one of many). This is demonstrated by the example in @redshift 's comment.
  So knowing the flaw is key for NA, because the negation of an NA "is" the flaw. So I hope this helps you see why knowing the flaw is so important.

  So this is interesting. I think this way of thinking will be super helpful for trickier NA questions. For the easier questions, looking for the answer that blocks the assumption I've found/ what I've found the argument takes for granted seems to be working. But thinking of it this way makes things a little clearer, connecting some of the elements about NA that I've known but haven't yet been able to integrate into a comprehensive approach.

  If I understand you correctly, when the correct answer choice is negated it should reflect the flaw I've found (even if it isn't an exact phrasing of said flaw). Is that right?

  Could you tell me a little bit more about what you believe prephrasing a flaw is vs. recognizing? I think making that distinction would be helpful.

  I think eliminating extra answer choices uses the MBT method will be helpful as well, so thank you for the reminder!
• 1 Like

  Bamboosprout Alum Member

  January 2019 1694 karma

  @Shrilaraune

  Could you tell me a little bit more about what you believe prephrasing a flaw is vs. recognizing? I think making that distinction would be helpful.

  You're doing great. It's always for the best to build a system. As to your question: they're the same. I just misunderstood you. I thought you were pre-phrasing the NA. It's ok to pre-phrase the flaw.