So, for a necessary assumption question, there can be a wrong answer that makes an argument logically valid IF say there is a separate answer choice that is weaker and may not make the argument logically follow but is necessary even to consider the argument.
For those of you with mathematic minds, the way I am thinking of the Necessary Assumption strength of support is to treat them as asymptotic (asymptote). You can't ever get to 0 by dividing something in half. For the necessary assumption, the support can be more and more marginal but it is always providing SOME support.
I feel like a better example is something like this:
You're the richest man alive.
NA: You have $1
NA: You have $100
NA: You have $1000
NA & SA: You have more money than any other living man.
SA: You have a trillion dollars.
The argument JY was giving related to a subjective matter - being the best basketball player alive. Being the richest man alive means something very specific. It would seem to me both sufficient and necessary to have more money than anyone (any other living man) if you wanted to be considered the richest man alive (assuming we are speaking about being rich in wealth).
In my example, we can make something as simple as having $1 the necessary assumption because it is necessary to have (at minimum) $1 to even be in the running of "richest man alive." But some necessary assumptions can give more support to the argument than others. Saying you have $100 is necessary and even better. Saying you have $1000 is necessary and even better than that!
Though having a trillion dollars would be sufficient as this indicates you are the richest man alive, as no individual has (or has ever had) that amount of money before, you don't need a trillion, it's not necessary because $250 billion would get the job done.
Yes necessary is already understood-it essentially allows the argument to still exist but doesn’t really strengthen it. It’s degree of strengthening is like if you think of the number 0 vs the number 0.000001…the second number is so close to 0 that we might as well consider it to be 0 for the purpose of working with it. I think that’s what JY means by the NA supporting it barely but how we should think of it as not supporting. Everything else you said makes sense also
Think about it more as a matter of degree. If I am a good driver, that means I can drive a car. If I can't drive a car, then it entails that I am not a good driver. If I said something like, I won a Formula 1 grand prix, therefore I am a good driver, that would be more akin to a sufficient assumption, because it would correctly entail that I am an excellent driver, but it is not necessary to be considered by most people to be a good driver.
I think this is a nice and useful diagram for comparing the support on these question types. I do think, though, that Strengthen really spans the entire spectrum on this diagram. For example, there are Strengthen questions were the correct answer merely defends the argument against a possible attack. You're given an argument that has several potential "wrecking balls," and the correct answer choice simply defends against one of those "wrecking balls." This does leave the argument in a slightly better position, but there could still be other "wrecking balls" left unaddressed. On the other hand, you could get a Strengthen question, and one of the answer choices makes the conclusion valid. Proving the conclusion true certainly strengthens the argument (it's the ultimate strengthener!), but you wouldn't eliminate that answer choice because it provides too much support (so much that it would even be correct if the question stems asked for a SA instead). I guess I'm just saying a correct answer choice to a Strengthen question can strengthen the argument just a little, or so much so that it makes the argument valid.
Completely agree with this. But usually, strengthening questions will not provide very much support and they rarely make the argument valid. So I believe the chart above is fair since most of the time, strengthening answer choices do far less work than a PSA or SA.
Thanks for bringing this diagram back. It makes a lot more sense now.
Necessary assumptions are literally just keeping the argument alive and the best example of that is a necessary assumption that any argument involving people today which provides that they are "alive."
NAs meet a very lowwww bar or loww threshhold that must be obviously there, otherwise, everything falls apart.
Hi SA and PSA are just acronyms for Sufficient Assumption and Pseudo-Sufficient Assumption. If you are following the syllabus, both of those question types were actually covered in the same curriculum! But basically the difference is that while SA makes an argument totally valid, PSA makes it almost valid, but you need to make a very small assumption to get there.
I'm actually skipping around the syllabus because i've already read a few LSAT books. None of the books that i've read have touched on PSA question types so this through me off guard. That makes sense and does not seem like a big difference. I guess a PSA is almost like MSS?
I need to just learn how to spot a PSA question type #help
From what I have seen, you can spot the difference in the question stem. Ex.
SA Q Stem: Which of the following, if assumed, allows the conclusion to be properly drawn.
PSA Q Stem: Which of the following, if assumed, would do most to justify the claim that...
Although, you can really just treat PSA as SA and be fine for the most part, but the key difference, which is illustrated in the question stem, is that SA allows no assumption, while PSA leaves a little wiggle room.
If you need practice on Q stems, the PSA and SA lesson includes flashcards and a quiz for question stems covered up to that point in the syllabus.
Got it, thank you for the response! I know the difference as to what the question asks for us to do BUT the only thing that still trips me up is when the word "principle" is used in PSA or Strengthen question stems. I'm trying to not overthink it. Like JY said, the word principle basically just means condition but should still be treated as a SA or strengthen question.
If one does well on the LSAT, then they studied hard.
However, one has to be alive to take the LSAT.
So if you're feeling discouraged, remember, everyone: even if we fail the sufficient assumption, at least we satisfy the necessary assumption by being alive.
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103 comments
I had literally written in my notes after the first NA video
necessary < strengthen < sufficient
lol glad to feel like im understanding!!
So, for a necessary assumption question, there can be a wrong answer that makes an argument logically valid IF say there is a separate answer choice that is weaker and may not make the argument logically follow but is necessary even to consider the argument.
this is what I pay for right here - this is magic.
I find the diagrams helpful, especially when linking different question types together :)
This is a very well illustrated and concise video. Great job.
#feedback
The written text under the videos is helpful and I’d love to see it added here!
Love NA questions hate SA questions lol
Great stuff! Thank you, JY!
I think about NA questions like covering a hole in the bottom of a ship (the argument) to prevent it to from sinking.
So when you negate a NA, you pierce a hole in the boat, and when you state a NA, you cover it up the bottom of the boat.
Ok so NA provides minimum support while SA provide extreme support
This was a great visual! Super helpful.
Would it be correct to say that the NA makes the argument possible? I feel like thats my take away/understanding thus far.
For those of you with mathematic minds, the way I am thinking of the Necessary Assumption strength of support is to treat them as asymptotic (asymptote). You can't ever get to 0 by dividing something in half. For the necessary assumption, the support can be more and more marginal but it is always providing SOME support.
NA allows me to exist as a person that wants to take the LSAT SA allows me to get a 180
ignore accidentally posted notes
You're the richest man alive.
NA: Your heart is beating.
SA: You have more money than anyone else.
I feel like a better example is something like this:
You're the richest man alive.
NA: You have $1
NA: You have $100
NA: You have $1000
NA & SA: You have more money than any other living man.
SA: You have a trillion dollars.
The argument JY was giving related to a subjective matter - being the best basketball player alive. Being the richest man alive means something very specific. It would seem to me both sufficient and necessary to have more money than anyone (any other living man) if you wanted to be considered the richest man alive (assuming we are speaking about being rich in wealth).
In my example, we can make something as simple as having $1 the necessary assumption because it is necessary to have (at minimum) $1 to even be in the running of "richest man alive." But some necessary assumptions can give more support to the argument than others. Saying you have $100 is necessary and even better. Saying you have $1000 is necessary and even better than that!
Though having a trillion dollars would be sufficient as this indicates you are the richest man alive, as no individual has (or has ever had) that amount of money before, you don't need a trillion, it's not necessary because $250 billion would get the job done.
Just my 2 cents.
I think this a good comment and revision. (King Solomon and Mansa Musa might count as trillionaires, not positive.)
Strengthen helps strengthen relationship between premises and conclusion
PSA makes argument almost valid, just lesser degree of certainty with assumption?
SA basically makes the argument perfect
NA is something already understood, does not add support for validity of argument?
#help (Added by Admin)
Yes necessary is already understood-it essentially allows the argument to still exist but doesn’t really strengthen it. It’s degree of strengthening is like if you think of the number 0 vs the number 0.000001…the second number is so close to 0 that we might as well consider it to be 0 for the purpose of working with it. I think that’s what JY means by the NA supporting it barely but how we should think of it as not supporting. Everything else you said makes sense also
#help kinda confused how NA "gives no support" yet is needed for argument ?
NA don't support as much because they plug up "what if" statements. They are proven by the conclusion instead of the other way around.
NA must be true if the conclusion is true. They aren't really in the argument as much as they live outside of the argument.
Premise --> Conclusion --> NA
Think about it more as a matter of degree. If I am a good driver, that means I can drive a car. If I can't drive a car, then it entails that I am not a good driver. If I said something like, I won a Formula 1 grand prix, therefore I am a good driver, that would be more akin to a sufficient assumption, because it would correctly entail that I am an excellent driver, but it is not necessary to be considered by most people to be a good driver.
I think this is a nice and useful diagram for comparing the support on these question types. I do think, though, that Strengthen really spans the entire spectrum on this diagram. For example, there are Strengthen questions were the correct answer merely defends the argument against a possible attack. You're given an argument that has several potential "wrecking balls," and the correct answer choice simply defends against one of those "wrecking balls." This does leave the argument in a slightly better position, but there could still be other "wrecking balls" left unaddressed. On the other hand, you could get a Strengthen question, and one of the answer choices makes the conclusion valid. Proving the conclusion true certainly strengthens the argument (it's the ultimate strengthener!), but you wouldn't eliminate that answer choice because it provides too much support (so much that it would even be correct if the question stems asked for a SA instead). I guess I'm just saying a correct answer choice to a Strengthen question can strengthen the argument just a little, or so much so that it makes the argument valid.
Completely agree with this. But usually, strengthening questions will not provide very much support and they rarely make the argument valid. So I believe the chart above is fair since most of the time, strengthening answer choices do far less work than a PSA or SA.
Thanks for bringing this diagram back. It makes a lot more sense now.
Necessary assumptions are literally just keeping the argument alive and the best example of that is a necessary assumption that any argument involving people today which provides that they are "alive."
NAs meet a very lowwww bar or loww threshhold that must be obviously there, otherwise, everything falls apart.
What is a PSA???? i think i missed that lesson
#help
Hi SA and PSA are just acronyms for Sufficient Assumption and Pseudo-Sufficient Assumption. If you are following the syllabus, both of those question types were actually covered in the same curriculum! But basically the difference is that while SA makes an argument totally valid, PSA makes it almost valid, but you need to make a very small assumption to get there.
I'm actually skipping around the syllabus because i've already read a few LSAT books. None of the books that i've read have touched on PSA question types so this through me off guard. That makes sense and does not seem like a big difference. I guess a PSA is almost like MSS?
I need to just learn how to spot a PSA question type #help
From what I have seen, you can spot the difference in the question stem. Ex.
SA Q Stem: Which of the following, if assumed, allows the conclusion to be properly drawn.
PSA Q Stem: Which of the following, if assumed, would do most to justify the claim that...
Although, you can really just treat PSA as SA and be fine for the most part, but the key difference, which is illustrated in the question stem, is that SA allows no assumption, while PSA leaves a little wiggle room.
If you need practice on Q stems, the PSA and SA lesson includes flashcards and a quiz for question stems covered up to that point in the syllabus.
Got it, thank you for the response! I know the difference as to what the question asks for us to do BUT the only thing that still trips me up is when the word "principle" is used in PSA or Strengthen question stems. I'm trying to not overthink it. Like JY said, the word principle basically just means condition but should still be treated as a SA or strengthen question.
this dude is effortlessly funny
If one does well on the LSAT, then they studied hard.
However, one has to be alive to take the LSAT.
So if you're feeling discouraged, remember, everyone: even if we fail the sufficient assumption, at least we satisfy the necessary assumption by being alive.
So the necessary assumption is needed or is "necessary" in order for the argument to exist or function? #help
yes, it's the "bare minimum" basically
Mean girls scene and you DIE