The only thing that confuses me is when we are supposed to use our real world knowledge and not? I feel like in multiple lessons its been used and others not so much.
@LogicallyUnreasonable Like for some of these, the answers are incorrect because alternative world examples exist to disprove them, even though they aren't existing in the stimulus universe.
For those confused, this is how I understand it: If new restaurants open, that is a sufficient condition for living standards to improve (we know this happens for sure). The improvement of living standards is a necessary condition of new restaurants opening; new restaurants cannot open without improving living standards -but, improved living standards is not sufficient for new restaurants having opened, because living standards could improve for other reasons.
It never says that new restaurants cannot open without improving living standards, you are assuming this because of the conditional format that it is placed under in the lesson. There is a one way relationship here that only shows that new restaurants are sufficient for living standards to improve. There is no necessity, pointing either way in this example IMO.
Respectfully, the LSAT will not care about an opinion or not. We have to throw out that, and focus on the arguments validity. It is VALID that if you open a restaurant, it is sufficient in improving the living standards.
I thiiink I've got my head around this. At this stage, I'm still finding it helpful to imagine what the English equivalent for the Lawgic here.
Unlike Argument 1, Argument 2 doesn't provide any context as to the breadth of what might otherwise be a superset. That is to say, maybe there are other things that would improve living standards for downtown residents (new sidewalks, for instance), but the premises don't tell us that. Argument 1 is different in this way. We know that cats are not the only type of mammal, and so therefore the sufficiency-necessity relationship can be situated as a subset-superset relationship.
But we can make Argument 1 look more like Argument 2 if we say this:
If cats exist, they are mammals.
Cats exist.
Therefore, cats are mammals.
While similar to the initial structure, this revision removes what we might call 'X,' right? It removes Garfield. It keeps the structure of subset and supersets (ie. cats->mammals-> existence), but doesn't tell us about membership. This more closely matches Argument 2 (in English, that is), which itself might be rephrased as:
If new restaurants exist (ie. open), they will improve the downtown living standards.
New restaurants exist.
Therefore, the downtown living standards will improve.
Now the question of supersets and subsets is all meddled up, but the form remains the same between both examples. Hopefully this makes some sense!
I'm still completely lost by using superscript and don't get why we have to over complicate this. I failed algebra a record number of times and the appeal of the LSAT was no math. Maybe I just need to reconsider my career plans.
For some people, the logic of LR questions are intuitive and you can parse out the logic without all of these notations. For most, learning "lawgic" is necessary to understanding some LSAT LR questions.
While you can totally just ignore this and take the loss on those few LR questions (unless you are just one of those people who can parse through logic in your head), understanding logic and logical fallacies is not only important to the LSAT but to a career in law and your future studies in law school.
I wouldn't equate this to math or overcomplicating the LSAT, in fact, it's a tool to simplify it. With practice it will become more intuitive BUT if having to learn logic is enough for you to rethink your career choice, maybe this isn't the one for you.
Either way, best of luck with your studying and I hope that the understanding comes to you :))
Alright friends. I've been trying to wrap my head around this whole [sufficient cond] -> [necessary cond] thing. Here are two relevant examples that I'm using to make this make more sense to me. (honestly not 100% sure if I got this right but for now my brain thinks this sounds reasonable lol)
Ex.1
If you get an 85 on the final, then you will get an A for the course.
That is:
Final=85 -> Course=A
Remembering sufficient/necessary conditions are all relationships. That is:
Getting an 85 on the final is a sufficient but necessary for getting an A for the course.
- You know that you got an 85 on the final, it's guaranteed that you are getting an A for the course. (sufficient)
- You could be getting an 90 on the final, you are still getting an A for the course. (not necessary)
Getting an A for the course is a necessary but not sufficient for getting an 85 on the final
- If you did not get an A for the course (you got a B+), then it is impossible that you got an 85 on the final. (necessary)
- You know that the final grade for the course is A, but you can't know exactly how you did on final. You could have got an 85. You could have got a 90. You don't know for sure. (not sufficient)
Ex.2
If you want to get wine at the restaurant, then you must be at least 19 years old.
That is:
wine -> 19 yro
- If I see people drinking wine at a restaurant, I can sufficiently conclude they are at least 19 years old.
- Getting wine at restaurant is not necessary for you to be at least 19 years old. You could be 25 and never drink.
- It is necessary that you are at least 19 to get wine at restaurant. If you are 18, restaurant can't serve you wine.
- Being 19 years old is not a sufficient condition for you to drink wine at the restaurant. You probably need to drive home. Then you can't drink.
@MarisolSanchez the way i think of it is the sufficient condition is one that result in the necessary condition. However, the necessary condition does not always result in the sufficient condition.
If new restaurants open, then living standards will improve.
new restaraunts open > living standards improve
However, living standards could improve in several other ways too, so new restaruants opening is not needed for the living standards to improve.
Came here after getting 149.4.23 wrong. Did not find the answer explanation as to why C over B helpful. Came here. Also not helpful, as the difference between subsets/supersets and conditional logic is key in that answer choice and I need more help understanding. Revamping and making this lesson more thorough would be helpful. #feedback
So they're functionally the same but actually different as one is pointing out a group A are in group B and all of C is in group A therefore C is in group B. The other is pointing out consequence. Rule: an action will result if X happens. X happens therefore X will be executed as a consequence.
I think this makes more sense after mapping out my own examples - someone correct me if I'm wrong here.
If rent goes down, then living conditions will improve for residents of 7Sage Apartments. Rent is going down for 7Sage Apartments, therefore living standards will improve for their residents.
This is not an argument that will require sets, as there are many different ways living conditions can improve. Saying in order for living conditions to improve, rent must go down doesn't work. It is fine to say that rent going down will improve living conditions, but that's not the whole story.
Rent is going down in 7Sage Apartments, which means residents' living standards will improve. JY is a resident of 7Sage Apartments. Therefore, his rent is going down and his living standards will improve.
This argument implies that there are sets being used, as it establishes JY as a member of a set (resident of 7Sage Apartments). The first argument doesn't establish membership for anything specific, it only contains a conditional relationship.
if the two relationships are considered the same for our purposes, why is is not okay for me to use the visualization of the circles for both. I know it is wonky to do it for things that are not really objects, but it helps me a lot. Am I shooting myself in the foot?
@Hashibiro, if it helps you visualize it, go for it. It just gets wonky because the modus ponens doesn't have members and the sufficient condition is more of a true or false, so it might cost you time when it comes to test taking, but while we practice, who cares?
Hey guys! Wondering if anyone has another perspective to explain why only the second premise gets translated into lawgic and not the first. I wish I could think about this more deeply, but unfortunately my brain does not like math like representative explanations. Thanks in advance!
The first is a set and grouping question. Think of it as groups inside groups. Banana is inside (an element) of the fruit set. So are grapes, apples, and tomatoes.
Set of fruit: {banana, grapes, apples, and tomatoes}
Now, in an argument, we can now make rules for those items (elements) in the set of fruit.
For example, Rule: “all Fruit are from seeds.” This rule is placed on the entire collection of fruit inside the set of fruit. It applies to apples since apple was stated as an element of our fruit set.
Therefore since all fruit are from seeds, and apples is a fruit, then apples must be from seeds.
In fact, by saying “all Fruit”, we’re saying, for something to be a fruit, it’s necessary to have came from a seed. If something has not come from a seed it cannot be a fruit since all fruits come from seeds.
however, if something came from a seed that does not mean it must be a fruit.
the first argument is saying if x is apart of this set or group, then x must be “this”.
The second argument is saying if x occurs, x creates y, and if y exists, Z must follow. (It’s a casual inference chain argument, not an argument involving groups).
Both have the same exact argument structure.
Argument 1
where A = cat, B = mammal
all “cats” are “mammals” (A -> B)
X is a cat (x is A, and remember all As are Bs).
Therefore, x is a mammal. (Since x is A and all A->B, x must also be B)
Argument 2
Let A = more restaurants open, B = improved living standard.
If more restaurants open then improved living standards. (A -> B).
More restaurants opened. (x = A, A = True -> B must also be True).
Living standards improve. (therefore B must have resulted, since A -> B).
Notice how argument 1 uses groups and rules/qualities about those groups (If under18 -> minor. X is under18, therefore X is minor).
While argument 2 uses causal reasoning. (If it’s winter time there’s less food, and it’s winter time, so therefore there’s less food.)
“Less food” is an amount, not a clear grouping like “fruit”. This is the reason why the second argument does not get translated like the first argument. “Increases, decreases, improves.” These are verbs of unspecified change, not nouns “Apple” or “fruit”.
what’s most important is that these two arguments produce the same logical structure despite one containing sets and groups, while the other contains A casual inference chain .
94 comments
Is it just me or is he talking faster in this video lol
k
@lorealol lmaooo real
The only thing that confuses me is when we are supposed to use our real world knowledge and not? I feel like in multiple lessons its been used and others not so much.
@LogicallyUnreasonable GLAD IM NOT ALONE. I just asked this same question a few videos back lmfaoo.
@LogicallyUnreasonable Like for some of these, the answers are incorrect because alternative world examples exist to disprove them, even though they aren't existing in the stimulus universe.
@InderpalSingh I feel the same!
@LogicallyUnreasonable agreed and everytime they act like its obvious were supposed to know which to utilize! glad im not going crazy
Bro making this a little more confusing then it has to be imo with the letters being like exponents and stuff lol
sadly agreed
Im glad i majored in philosophy, haha!
I don't think mentioning the difference was necessary in the first place. Now my brain will start marking them different sort of..
A --> B
A
Therefore, B
vs
A --> B
C --> A
Therefore, C --> B
is it me or does he sound like he's talking faster?
@LoganHjermstad You can slow down the playback speed to 0.8, thats what i did
is this approach actually effective or not? How many people do this and how did it help you?
So far I am having extreme growing pains applying this method to solving LSAT questions ...
For those confused, this is how I understand it: If new restaurants open, that is a sufficient condition for living standards to improve (we know this happens for sure). The improvement of living standards is a necessary condition of new restaurants opening; new restaurants cannot open without improving living standards -but, improved living standards is not sufficient for new restaurants having opened, because living standards could improve for other reasons.
It never says that new restaurants cannot open without improving living standards, you are assuming this because of the conditional format that it is placed under in the lesson. There is a one way relationship here that only shows that new restaurants are sufficient for living standards to improve. There is no necessity, pointing either way in this example IMO.
Respectfully, the LSAT will not care about an opinion or not. We have to throw out that, and focus on the arguments validity. It is VALID that if you open a restaurant, it is sufficient in improving the living standards.
I thiiink I've got my head around this. At this stage, I'm still finding it helpful to imagine what the English equivalent for the Lawgic here.
Unlike Argument 1, Argument 2 doesn't provide any context as to the breadth of what might otherwise be a superset. That is to say, maybe there are other things that would improve living standards for downtown residents (new sidewalks, for instance), but the premises don't tell us that. Argument 1 is different in this way. We know that cats are not the only type of mammal, and so therefore the sufficiency-necessity relationship can be situated as a subset-superset relationship.
But we can make Argument 1 look more like Argument 2 if we say this:
If cats exist, they are mammals.
Cats exist.
Therefore, cats are mammals.
While similar to the initial structure, this revision removes what we might call 'X,' right? It removes Garfield. It keeps the structure of subset and supersets (ie. cats->mammals-> existence), but doesn't tell us about membership. This more closely matches Argument 2 (in English, that is), which itself might be rephrased as:
If new restaurants exist (ie. open), they will improve the downtown living standards.
New restaurants exist.
Therefore, the downtown living standards will improve.
Now the question of supersets and subsets is all meddled up, but the form remains the same between both examples. Hopefully this makes some sense!
THIS helped me lock this lesson's concept in in my head.
Thank you for spelling it out like this.
my predicate logic professor would lose his mind if i told him i was conflating categorical syllogism and modus ponens
Until he explained how they were different. I assumed they were the same.
I'm still completely lost by using superscript and don't get why we have to over complicate this. I failed algebra a record number of times and the appeal of the LSAT was no math. Maybe I just need to reconsider my career plans.
No fr...
For some people, the logic of LR questions are intuitive and you can parse out the logic without all of these notations. For most, learning "lawgic" is necessary to understanding some LSAT LR questions.
While you can totally just ignore this and take the loss on those few LR questions (unless you are just one of those people who can parse through logic in your head), understanding logic and logical fallacies is not only important to the LSAT but to a career in law and your future studies in law school.
I wouldn't equate this to math or overcomplicating the LSAT, in fact, it's a tool to simplify it. With practice it will become more intuitive BUT if having to learn logic is enough for you to rethink your career choice, maybe this isn't the one for you.
Either way, best of luck with your studying and I hope that the understanding comes to you :))
Alright friends. I've been trying to wrap my head around this whole [sufficient cond] -> [necessary cond] thing. Here are two relevant examples that I'm using to make this make more sense to me. (honestly not 100% sure if I got this right but for now my brain thinks this sounds reasonable lol)
Ex.1
If you get an 85 on the final, then you will get an A for the course.
That is:
Final=85 -> Course=A
Remembering sufficient/necessary conditions are all relationships. That is:
Getting an 85 on the final is a sufficient but necessary for getting an A for the course.
- You know that you got an 85 on the final, it's guaranteed that you are getting an A for the course. (sufficient)
- You could be getting an 90 on the final, you are still getting an A for the course. (not necessary)
Getting an A for the course is a necessary but not sufficient for getting an 85 on the final
- If you did not get an A for the course (you got a B+), then it is impossible that you got an 85 on the final. (necessary)
- You know that the final grade for the course is A, but you can't know exactly how you did on final. You could have got an 85. You could have got a 90. You don't know for sure. (not sufficient)
Ex.2
If you want to get wine at the restaurant, then you must be at least 19 years old.
That is:
wine -> 19 yro
- If I see people drinking wine at a restaurant, I can sufficiently conclude they are at least 19 years old.
- Getting wine at restaurant is not necessary for you to be at least 19 years old. You could be 25 and never drink.
- It is necessary that you are at least 19 to get wine at restaurant. If you are 18, restaurant can't serve you wine.
- Being 19 years old is not a sufficient condition for you to drink wine at the restaurant. You probably need to drive home. Then you can't drink.
@MarisolSanchez the way i think of it is the sufficient condition is one that result in the necessary condition. However, the necessary condition does not always result in the sufficient condition.
If new restaurants open, then living standards will improve.
new restaraunts open > living standards improve
However, living standards could improve in several other ways too, so new restaruants opening is not needed for the living standards to improve.
sigh
Came here after getting 149.4.23 wrong. Did not find the answer explanation as to why C over B helpful. Came here. Also not helpful, as the difference between subsets/supersets and conditional logic is key in that answer choice and I need more help understanding. Revamping and making this lesson more thorough would be helpful. #feedback
couldve said theyre "lawgically equivalent" too har har
So they're functionally the same but actually different as one is pointing out a group A are in group B and all of C is in group A therefore C is in group B. The other is pointing out consequence. Rule: an action will result if X happens. X happens therefore X will be executed as a consequence.
I think this makes more sense after mapping out my own examples - someone correct me if I'm wrong here.
If rent goes down, then living conditions will improve for residents of 7Sage Apartments. Rent is going down for 7Sage Apartments, therefore living standards will improve for their residents.
This is not an argument that will require sets, as there are many different ways living conditions can improve. Saying in order for living conditions to improve, rent must go down doesn't work. It is fine to say that rent going down will improve living conditions, but that's not the whole story.
Rent is going down in 7Sage Apartments, which means residents' living standards will improve. JY is a resident of 7Sage Apartments. Therefore, his rent is going down and his living standards will improve.
This argument implies that there are sets being used, as it establishes JY as a member of a set (resident of 7Sage Apartments). The first argument doesn't establish membership for anything specific, it only contains a conditional relationship.
I really hope this makes sense, lol!
I get it but I don't ! Been on this part of the course for a while now !
#feedback It would be helpful to have the ability to use subscript and superscript in the notes section
Thank you for adding this lesson! This has confused me for some time.
if the two relationships are considered the same for our purposes, why is is not okay for me to use the visualization of the circles for both. I know it is wonky to do it for things that are not really objects, but it helps me a lot. Am I shooting myself in the foot?
@Amelia_D No, I don't think you are. It's a useful visual for If-then too.
@Kevin_Lin Thanks Kevin!
@Amelia_D I do the reverse, where I prefer representing everything with arrows and exclamation points, e.g. A ⟹ B and !B ⟹ !A
I think both of our methods are fine :)
@Hashibiro, if it helps you visualize it, go for it. It just gets wonky because the modus ponens doesn't have members and the sufficient condition is more of a true or false, so it might cost you time when it comes to test taking, but while we practice, who cares?
Hey guys! Wondering if anyone has another perspective to explain why only the second premise gets translated into lawgic and not the first. I wish I could think about this more deeply, but unfortunately my brain does not like math like representative explanations. Thanks in advance!
@juliairelandd
The first is a set and grouping question. Think of it as groups inside groups. Banana is inside (an element) of the fruit set. So are grapes, apples, and tomatoes.
Set of fruit: {banana, grapes, apples, and tomatoes}
Now, in an argument, we can now make rules for those items (elements) in the set of fruit.
For example, Rule: “all Fruit are from seeds.” This rule is placed on the entire collection of fruit inside the set of fruit. It applies to apples since apple was stated as an element of our fruit set.
Therefore since all fruit are from seeds, and apples is a fruit, then apples must be from seeds.
In fact, by saying “all Fruit”, we’re saying, for something to be a fruit, it’s necessary to have came from a seed. If something has not come from a seed it cannot be a fruit since all fruits come from seeds.
however, if something came from a seed that does not mean it must be a fruit.
the first argument is saying if x is apart of this set or group, then x must be “this”.
The second argument is saying if x occurs, x creates y, and if y exists, Z must follow. (It’s a casual inference chain argument, not an argument involving groups).
Both have the same exact argument structure.
Argument 1
where A = cat, B = mammal
all “cats” are “mammals” (A -> B)
X is a cat (x is A, and remember all As are Bs).
Therefore, x is a mammal. (Since x is A and all A->B, x must also be B)
Argument 2
Let A = more restaurants open, B = improved living standard.
If more restaurants open then improved living standards. (A -> B).
More restaurants opened. (x = A, A = True -> B must also be True).
Living standards improve. (therefore B must have resulted, since A -> B).
Notice how argument 1 uses groups and rules/qualities about those groups (If under18 -> minor. X is under18, therefore X is minor).
While argument 2 uses causal reasoning. (If it’s winter time there’s less food, and it’s winter time, so therefore there’s less food.)
“Less food” is an amount, not a clear grouping like “fruit”. This is the reason why the second argument does not get translated like the first argument. “Increases, decreases, improves.” These are verbs of unspecified change, not nouns “Apple” or “fruit”.
what’s most important is that these two arguments produce the same logical structure despite one containing sets and groups, while the other contains A casual inference chain .
If A -> B
A
Therefore, B. Same structure.
Hope that helped.