I had to lean on my own intuition to get #3. The way I thought of it is that the sufficient condition(s) must guarantee the necessary condition.
I know from the sentence structure that "infected by the virus" is at least the first sufficient condition (Anyone is a Group 1 indicator, variation of Any), and "produce antibodies to fight the virus" is the necessary condition (it is a required outcome of being "infected by the virus." If you remove "after a week", then the stimulus turns into "If A then B")
Looking at "after a week", does it guarantee that antibodies will be produced to fight the virus, or is it a required outcome if someone is infected by the virus?
It doesn't make sense to say that "after a week" is a required outcome of being infected with the virus, but it does make sense to say that "after a week" (or a week's worth of time) does guarantee that antibodies will be produced to fight the virus in conjunction with being infected with the virus.
Therefore:
infected by the virus and after a week → produce antibodies to fight the virus
/produce antibodies to fight the virus → /infected by the virus or /after a week
If one does not produce antibodies to fight the virus, they are not infected by the virus or have not waited a week.
Another thing that helped me is remembering that we must consider all statements as true. Try not to let your "outside knowledge" inform the logic. Obviously, it isn't a real-world guarantee that waiting 1 week will always produce antibodies, but if all the statements are true, then it is valid.
I'm glad I took my time with #6 and paid attention to the last sentence. I looked at the last sentence as if it was adding background information and did not diagram that part.
enjoying all these quizzes back to back for the sake of repetitiveness. per my #feedback earlier, it still would be helpful to have some quizzes, in addition to these, after the specific lesson.
Hey there, thanks for sharing your feedback with us! It's incredibly helpful, and I'm definitely going to pass it along to the rest of the team. Your ideas help us make things better for everyone, so please don't hesitate to share more if you have them. Thanks again!
Unpopular opinion: I like the AI Coach. It provided the following notes on Q2 because I skipped the predicate grammar lesson.
LSAT Grammar Shortcut: The Hidden "AND" (Modified Nouns)
The Rule: The LSAT often hides "AND" statements inside descriptive grammar. When a noun in the predicate is modified by a descriptive phrase (using words like with, who are, or that have), it acts as a hidden conjunction. To fit the description, the subject must be both things.
The Example:"All trees are perennial plants with elongated stems."
The Breakdown: Even though the word "and" isn't in the sentence, for something to be a tree, it must meet two requirements:
It must be a perennial plant.
It must have an elongated stem.
The Lawgic Translation:
Original: Tree → Perennial AND Elongated Stem
Contrapositive (De Morgan's): /Perennial OR /Elongated Stem → /Tree (Meaning: If a plant is NOT perennial, OR if it does NOT have an elongated stem, it cannot be a tree. Failing just one requirement is enough to disqualify it.)
The Takeaway: Whenever you see a noun glued to a description, ask yourself: "Does this mean it has to be both things?" If yes, instantly treat it as an AND statement so you don't miss the contrapositive flip
#2 definitely tripped me up, I didn't think of "with" as a conjunction and thought that "perennial plants with elongated stems" was all one big condition.
@AmayaUkandu totally feel you. the first time i did this i didn't even realize that with could have the same meaning. i took a couple days off and came back to this exercise after reading my notes and it was automatically clear to me. i think it will just be more obvious with time and practice.
I think it's clarified if you think in terms of sets.
If you were to set 21 or 21+ as a superset (the necessary condition) and legal as the subset (sufficient condition). Then is means that there may be a case where someone is not in the "legal to buy" set, but still within the 21 or older set.
But in strict context of the passage, that is not what the logic is saying. In the sentence it says that ANYONE (so all) 21 or 21+ can buy. So 21 and 21+ has to be the sufficient condition.
@martinauer23 This is too based on outside knowledge, it is perfectly possible that somebody 21 or older than 21 could not be legal to buy alcohol from this logic. Even IRL it is possible, imagine if they had a DUI or something. Being 21/21+ DOES NOT ensure legality
i already know my biggest weakness is gonna be confusing sufficiency for necessity when there are no indicators... does anyone have any advice or ways i can do more lessons on this?
@NoraElkhyati Something that helps me is grouping the concepts into the subset and superset (sufficient and necessary, respectively). For instance, for question 2, I identified trees as a subset to the supersets perennial plants and plants with stems; trees fit these two criterion, but there are other perennial plants and plants with elongated stems that are not trees, thus making trees the subset (sufficient) and per./e-stem the superset (necessary). This would therefore translate to, with the use of de Morgan's for the contrapositive:
T -> per. and e-stem; contrapositive of /per. or /e-stem -> /T.
If you approach the sentence, "All cats are mammals and are adorable," you could identify that mammals and adorable are two supersets; there are other things that fit into these categories other than cats. However, cats also fit into these two as a subset. Therefore, cat must be the sufficient condition and mammals and adorable must be the necessary conditions. This comes out to:
C -> M and A; contrapositive of /M or /A -> /C.
I hope this makes sense and is of any assistance to you guys! Best of luck on the LSAT, you got this!!
@NoraElkhyati always thing about set and super set. also helps to think that sufficient (set) guarantees something to happen. But the necessary condition(super set) does not guarantee. example if it is raining, then the ground is wet.
you see the rains is sufficient and guarantee that the ground is wet but the ground being wet is not guarantee that it is raining. Could be wet for any other reason.
315 comments
crashing out
@jjsukkar this made me laugh and lightened today's study session mood. i am with you on that, my friend
@jjsukkar 😩😩😩
"There's no explicit conjunction indicator present"
Me, who spends like 5 minutes trying to find it:
back here after 8 months of studying.... this stuff is important I promise!!
Six questions. Scandalous.
Honestly... I can't diagram but I understand the logic. Running on prayers and vibes rn.
Man, #3 was hard.
I had to lean on my own intuition to get #3. The way I thought of it is that the sufficient condition(s) must guarantee the necessary condition.
I know from the sentence structure that "infected by the virus" is at least the first sufficient condition (Anyone is a Group 1 indicator, variation of Any), and "produce antibodies to fight the virus" is the necessary condition (it is a required outcome of being "infected by the virus." If you remove "after a week", then the stimulus turns into "If A then B")
Looking at "after a week", does it guarantee that antibodies will be produced to fight the virus, or is it a required outcome if someone is infected by the virus?
It doesn't make sense to say that "after a week" is a required outcome of being infected with the virus, but it does make sense to say that "after a week" (or a week's worth of time) does guarantee that antibodies will be produced to fight the virus in conjunction with being infected with the virus.
Therefore:
infected by the virus and after a week → produce antibodies to fight the virus
/produce antibodies to fight the virus → /infected by the virus or /after a week
If one does not produce antibodies to fight the virus, they are not infected by the virus or have not waited a week.
Another thing that helped me is remembering that we must consider all statements as true. Try not to let your "outside knowledge" inform the logic. Obviously, it isn't a real-world guarantee that waiting 1 week will always produce antibodies, but if all the statements are true, then it is valid.
A video explaining the answers would be very helpful I am having trouble with this
Videos have arrived
I'm glad I took my time with #6 and paid attention to the last sentence. I looked at the last sentence as if it was adding background information and did not diagram that part.
5/6 the virus one was tough but I understand it now!
@petvma same! i thought 1 week was the necessary condition
I def fell for the red herring bs.
enjoying all these quizzes back to back for the sake of repetitiveness. per my #feedback earlier, it still would be helpful to have some quizzes, in addition to these, after the specific lesson.
Hey there, thanks for sharing your feedback with us! It's incredibly helpful, and I'm definitely going to pass it along to the rest of the team. Your ideas help us make things better for everyone, so please don't hesitate to share more if you have them. Thanks again!
I definitely gonna need more practice. I get the idea but am struggling to come up with the answers my self.
Unpopular opinion: I like the AI Coach. It provided the following notes on Q2 because I skipped the predicate grammar lesson.
LSAT Grammar Shortcut: The Hidden "AND" (Modified Nouns)
The Rule: The LSAT often hides "AND" statements inside descriptive grammar. When a noun in the predicate is modified by a descriptive phrase (using words like with, who are, or that have), it acts as a hidden conjunction. To fit the description, the subject must be both things.
The Breakdown: Even though the word "and" isn't in the sentence, for something to be a tree, it must meet two requirements:
It must be a perennial plant.
It must have an elongated stem.
The Lawgic Translation:
Original: Tree → Perennial AND Elongated Stem
Contrapositive (De Morgan's): /Perennial OR /Elongated Stem → /Tree (Meaning: If a plant is NOT perennial, OR if it does NOT have an elongated stem, it cannot be a tree. Failing just one requirement is enough to disqualify it.)
The Takeaway: Whenever you see a noun glued to a description, ask yourself: "Does this mean it has to be both things?" If yes, instantly treat it as an AND statement so you don't miss the contrapositive flip
@Shwani Where is the AI Coach? I can't seem to find it.
@Naty its the chat function in the top left
@MichaelLowery43 Thank you!
#2 definitely tripped me up, I didn't think of "with" as a conjunction and thought that "perennial plants with elongated stems" was all one big condition.
Maybe I need to look up what conjunctions are lol
@AmayaUkandu totally feel you. the first time i did this i didn't even realize that with could have the same meaning. i took a couple days off and came back to this exercise after reading my notes and it was automatically clear to me. i think it will just be more obvious with time and practice.
I feel like 5 should be a Biconditional. 21+ is sufficient for being legal but being legal is also sufficient for being 21+.
Agreed!
I think it's clarified if you think in terms of sets.
If you were to set 21 or 21+ as a superset (the necessary condition) and legal as the subset (sufficient condition). Then is means that there may be a case where someone is not in the "legal to buy" set, but still within the 21 or older set.
But in strict context of the passage, that is not what the logic is saying. In the sentence it says that ANYONE (so all) 21 or 21+ can buy. So 21 and 21+ has to be the sufficient condition.
this is a really good comment ^^ haven't really taken subsets/supersets seriously till now, but you showed me how to make that idea useful
@martinauer23 This is too based on outside knowledge, it is perfectly possible that somebody 21 or older than 21 could not be legal to buy alcohol from this logic. Even IRL it is possible, imagine if they had a DUI or something. Being 21/21+ DOES NOT ensure legality
5/6, didn't answer #3 because I was confused.
i already know my biggest weakness is gonna be confusing sufficiency for necessity when there are no indicators... does anyone have any advice or ways i can do more lessons on this?
@NoraElkhyati This is also my biggest problem, it is confusing sufficiency for necessity
@NoraElkhyati Something that helps me is grouping the concepts into the subset and superset (sufficient and necessary, respectively). For instance, for question 2, I identified trees as a subset to the supersets perennial plants and plants with stems; trees fit these two criterion, but there are other perennial plants and plants with elongated stems that are not trees, thus making trees the subset (sufficient) and per./e-stem the superset (necessary). This would therefore translate to, with the use of de Morgan's for the contrapositive:
T -> per. and e-stem; contrapositive of /per. or /e-stem -> /T.
If you approach the sentence, "All cats are mammals and are adorable," you could identify that mammals and adorable are two supersets; there are other things that fit into these categories other than cats. However, cats also fit into these two as a subset. Therefore, cat must be the sufficient condition and mammals and adorable must be the necessary conditions. This comes out to:
C -> M and A; contrapositive of /M or /A -> /C.
I hope this makes sense and is of any assistance to you guys! Best of luck on the LSAT, you got this!!
@NoraElkhyati always thing about set and super set. also helps to think that sufficient (set) guarantees something to happen. But the necessary condition(super set) does not guarantee. example if it is raining, then the ground is wet.
you see the rains is sufficient and guarantee that the ground is wet but the ground being wet is not guarantee that it is raining. Could be wet for any other reason.
Hope this help
6/6!!!
Thank you for a much shorter skillbuilder lesson
Didn't get all of them right but I understand the explanation. A win is a win!🤷🏽♀️
@ChelsiSmith Right! I kinda feel like the explanations make me go against the grain of my better judgement. This process is so intuitive.
is the voice different?
I got tricked on question 6
Woo! This makes more sense! lol
4/5 misread the antibodies question but quickly understood my mistake. I hope DeMorgan would be proud
anyone else interperate #5 as an "and" question? this was my answer:
21+ & inUS → legaly purchase alc
contrapositive: /(legaly purchase alc) → /21+ or /inUS
I think my answer makes sense but maybe on the actual test looking at the question stem would help to provide context on how to translate into lawgic