Would you say this can be simplified to: "If the sufficient condition is false, the necessary condition can be true or false", and "if the necessary condition is true, the sufficient condition can be true or false"?
Ok so I also found this lesson confusing. What I think the key take away here is that just because the necessary condition is true tells us nothing about the sufficient condition. That's it.
My example:
All moms use the kitchen. I use the kitchen. Therefore, I am a mom
Lawgic:
Moms -> use kitchen
I KITCHEN
--
I MOM
This is Invalid. WHY? Because I'M NOT A MOM. I AM A SINGLE DUDE. Just because I am using the kitchen does that mean I am a mom? NO!
If you thought me using the kitchen meant I'm a mom you are confusing sufficiency for necessity. You are saying that using the kitchen is SUFFICENT for being a mom. you are saying "All those who use the kitchen are mom".
AFFIRMING THE NECESSARY CONDITION TELLS YOU NOTHING ABOUT THE SUFFICIENT CONDITION
All we know from the stimulus is that All moms use the kitchen.
Mom = Sufficient
Using kitchen = Necessary
If I affirm the necessary condition by saying "I use the kitchen" does that tell you anything about if I am a mom or not?
If the necessary condition is satisfied, it yields no information about the sufficient condition. The sufficient condition could be true or could be false.
@DorinLee Hi I don't know if this is helpful but I think by the statement "the only problem is that you made up your own premise" they mean that you alone had to assume that B-->A to make the conclusion valid. The stimulus only tells you that A--> B. The only way to make this conclusion valid is to add in this premise you made up (B--> A). So the conclusion is not valid given the premises the stimulus gives you.
If you are a Jedi, Then you use the Force. Dooku uses the Force. Dooku is a Jedi.
This is INVALID--
Lawgic:
Jedi-> Force
Dooku -> Force
Dooku -> Jedi
Imagine two circles, small circle being Jedi and it's inside the Force.... Dooku can be anything other than a Jedi and still be in the big circle "Uses the force".
This would be a VALID argument:
Only Jedi use the Force. Dooku uses the Force. Therefore, Dooku is a Jedi.
(remember Only is group 2 indicator)
Lawgic:
Force -> Jedi
Dooku -> Force
Dooku -> Jedi
Lets chain this up:
Dooku -> Force -> Jedi
so...
Dooku -> Jedi
Because Dooku uses the Force and thats sufficient to be a Jedi than that makes sense as he's already in the small circle so he must be a Jedi.
For anyone confused by the second example using "Only Jedi..." They are just trying to help explain that many students assume that when they see "all" in a statement that they confuse it with "only".
The wording is confusing, but once I figured that out it helped to better understand this!
@VanillaCat great way to visualize is the circles example: necessary is the bigger circle, sufficient is the smaller circle within the bigger one. Sufficient is always in the necessary's circle, but the necessary's circle can have other sufficients inside it as well
@VanillaCat Wait I am a little confused about the second bullet point... how can failing the necessary not guarantee failing the sufficient?
Going back to a previous example of NYC -> USA... if I do not satisfy USA, then I cannot satisfy NYC.
I understand you can satisfy NYC if your necessary is New York or East Coast, is that what you are explaining? That they are other methods of satisfying the sufficient?
@Kellbell206 hello yes the second one just refers to /USA --> /NYC. i'm a little confused what you are asking, if the necessary is NY, then yes NYC or East Coast could be sufficient conditions. but if we are looking at relationship between NYC and USA, failing the necessary (USA) means there's no possible way we could meet the sufficient (NYC). mayb your first sentence is where confusion lies? failing the necessary DOES guarantee we failed the sufficient (failing to be in USA does guarantee failing to be in NYC). 😊
I completely understand it but I wish you guys wouldn’t show the invalid argument in lawgic. When you’re still trying to grasp everything it’s easy to see and have it manipulate your thinking, even when you know it’s wrong.
Only Arabic-speakers get PhDs. Chris is an Arabic speaker. Therefore Chris gets a PhD.
If gets a PhD, then an Arabic Speaker, written
PhD->Arabic-speaker
Now here's where you don't want to mess up. It says Chris is in that "Arabic-Speaker" portion, or in other words, he's someone in the necessary condition position. But we can't work backwards. We can't say if Chris (the necessary) speaks Arabic then he gets a PhD.
It's easier to see if we use three topics, as it builds on earlier lessons:
Why is he making these lessons harder than they need to be? He clearly states in the previous chapters that we should assign symbols that help us remember as much information as possible and does the complete opposite when giving examples..
This chapter is so confusing, first, using A,B to in Lawgic is not representive enough. Also, the second lawgic is seemingly wrong, but it says it's valid.
I do not understand the second example. If the conditional indicator is Only, that translates to logic Uses Force --> Jedi. Since Dooku uses the force, he triggered the sufficient and is a Jedi. This is a valid logic. But why did the text say I made up my own premise? If the conditional indicator is only, I did not make anything up did I? it's very confusing.
Why is the Lawgic shorthand for Jedi and Force all of the sudden A and B instead of J and F in these examples? It makes it impossible to match english to the Lawgic shorthand in order to follow along. What are we doing here? #feedback
i don't understand why in the Lawgic part of this lesson, is there not an actual usage of the symbols that correlate with the English statement form? It makes understanding this lesson 10x harder than if we could use J for Jedi, F for Force, or CD for Count Dooku.
I don't understand the last paragraph "The only problem is that you made up your own premise B -> A. The actual premise is A -> B. You confused sufficiency for necessity."
The rest of the lesson makes sense, but I'm totally lost when I read that. Maybe make a video or remove/clarify that paragraph? I don't see what that really adds here.
@john Agreed that confused me. I think they're just saying that the conditional argument follows A--> B, xA, xB. They chose to flip it for the sake of correcting the example but it does not follow the traditional (correct) conditional argument sequence.
Idk if this will help some of you all, but it helped me understand this whole thing better.
I found this on 7sage btw.
"So imagine you are given two premises:
1.) A relationship: Y--->G--->H--->B
2.) A fact: Not H
What conclusions can you draw?
Not H is a necessary condition for G AND it is a necessary condition for Y (since Y implies H). So, you are failing a necessary (required) condition for G and Y. Thus, you must have Not G and Not Y.
H is a sufficient condition for B. Failing the sufficient condition doesn't trigger anything because there might be other ways B can trigger".
So if you are failing a necessary condition then you can make a valid conclusion for the sufficient. But if you are satisfying a necessary, then you cannot draw a conclusion about the sufficient, because we dont know what happens to the sufficient.
Valid conclusion: Only dogs play outside. Blanche plays outside. Therefore, Blanche is a dog.
Invalid conclusion: All dogs play outside. Blanche plays outside. Therefore, Blanche is a dog.
In the invalid conclusion, Blanche could be a part of another group since it does not explicitly state that you have to be a dog to play outside. She could be human, a cat, etc.
150 comments
Would you say this can be simplified to: "If the sufficient condition is false, the necessary condition can be true or false", and "if the necessary condition is true, the sufficient condition can be true or false"?
Correct!
you rock for this!!! Such an easy way to remember and catch a trap
can you please explain this?
@amarareid1410 thank you so much for this
For those who have never seen Star Wars (me):
(1) All pilots can fly airplanes. Alex can fly airplanes. Therefore, Alex is a pilot.
This is invalid because someone could know how to fly planes and not be a pilot.
(2) Only pilots can fly airplanes. Alex can fly airplanes. Therefore, Alex is a pilot.
This is valid because anyone who can fly airplanes must be a pilot.
@KaraSwider You need to see Star Wars, nonnegotiable. Thanks for the example though.
@KaraSwider Thank you!!!
Ok so I also found this lesson confusing. What I think the key take away here is that just because the necessary condition is true tells us nothing about the sufficient condition. That's it.
My example:
All moms use the kitchen. I use the kitchen. Therefore, I am a mom
Lawgic:
Moms -> use kitchen
I KITCHEN
--
I MOM
This is Invalid. WHY? Because I'M NOT A MOM. I AM A SINGLE DUDE. Just because I am using the kitchen does that mean I am a mom? NO!
If you thought me using the kitchen meant I'm a mom you are confusing sufficiency for necessity. You are saying that using the kitchen is SUFFICENT for being a mom. you are saying "All those who use the kitchen are mom".
AFFIRMING THE NECESSARY CONDITION TELLS YOU NOTHING ABOUT THE SUFFICIENT CONDITION
All we know from the stimulus is that All moms use the kitchen.
Mom = Sufficient
Using kitchen = Necessary
If I affirm the necessary condition by saying "I use the kitchen" does that tell you anything about if I am a mom or not?
If the necessary condition is satisfied, it yields no information about the sufficient condition. The sufficient condition could be true or could be false.
@Student101 this made me giggle but also helped, thank you
@Student101 It's hard being a single mom when you're a childless, single-man. It's a struggle, fr fr
@Student101 holy moly this was so friggin helpful I took these notes instead of the 7sage summary
#feedback
That last paragraph keeps tripping me up. A video would prob explain this better to avoid confusion.
@DaisyVidana Agreed.
@DaisyVidana i agree! like what does that mean "The Only problem is that you made up your own premise B->A"?!! Is that valid, or nah?
@DorinLee I think since there's an only, Jedi should be the necessary
A (Force) -> B (Jedi)
xA
-----
xB
@DorinLee Hi I don't know if this is helpful but I think by the statement "the only problem is that you made up your own premise" they mean that you alone had to assume that B-->A to make the conclusion valid. The stimulus only tells you that A--> B. The only way to make this conclusion valid is to add in this premise you made up (B--> A). So the conclusion is not valid given the premises the stimulus gives you.
I hope this helps:
(if, then always helped me)
If you are a Jedi, Then you use the Force. Dooku uses the Force. Dooku is a Jedi.
This is INVALID--
Lawgic:
Jedi-> Force
Dooku -> Force
Dooku -> Jedi
Imagine two circles, small circle being Jedi and it's inside the Force.... Dooku can be anything other than a Jedi and still be in the big circle "Uses the force".
This would be a VALID argument:
Only Jedi use the Force. Dooku uses the Force. Therefore, Dooku is a Jedi.
(remember Only is group 2 indicator)
Lawgic:
Force -> Jedi
Dooku -> Force
Dooku -> Jedi
Lets chain this up:
Dooku -> Force -> Jedi
so...
Dooku -> Jedi
Because Dooku uses the Force and thats sufficient to be a Jedi than that makes sense as he's already in the small circle so he must be a Jedi.
After reading these I think that the videos help me grasp it more.
For anyone confused by the second example using "Only Jedi..." They are just trying to help explain that many students assume that when they see "all" in a statement that they confuse it with "only".
The wording is confusing, but once I figured that out it helped to better understand this!
This helped me a lot; thank you for sharing!
THIS rocked my world. Thank you!
Failing a sufficient condition doesn't mean they cannot meet the necessary condition
Failing a necessary condition does mean that they cannot meet the sufficient condition
Meeting a sufficient condition does mean that they meet the necessary condition
Meeting a necessary condition does not mean that they meet the sufficient condition
@VanillaCat needed this!
@VanillaCat great way to visualize is the circles example: necessary is the bigger circle, sufficient is the smaller circle within the bigger one. Sufficient is always in the necessary's circle, but the necessary's circle can have other sufficients inside it as well
@epayne17 Yesss this is what i picture every time
@VanillaCat Wait I am a little confused about the second bullet point... how can failing the necessary not guarantee failing the sufficient?
Going back to a previous example of NYC -> USA... if I do not satisfy USA, then I cannot satisfy NYC.
I understand you can satisfy NYC if your necessary is New York or East Coast, is that what you are explaining? That they are other methods of satisfying the sufficient?
@Kellbell206 hello yes the second one just refers to /USA --> /NYC. i'm a little confused what you are asking, if the necessary is NY, then yes NYC or East Coast could be sufficient conditions. but if we are looking at relationship between NYC and USA, failing the necessary (USA) means there's no possible way we could meet the sufficient (NYC). mayb your first sentence is where confusion lies? failing the necessary DOES guarantee we failed the sufficient (failing to be in USA does guarantee failing to be in NYC). 😊
I had a hard time understanding until I did this.
All cats (A) are mammals (B)
Tom is a mammal(B)
Therefore Tom is a cat (A) INVALID ARGUMENT
This is invalid because Tom could be a cat, or a dog, or a cow, or a sheep...etc
Thank you! This helped so much.
I completely understand it but I wish you guys wouldn’t show the invalid argument in lawgic. When you’re still trying to grasp everything it’s easy to see and have it manipulate your thinking, even when you know it’s wrong.
A trick that may work for people is thinking about this chronologically/left-to-right.
If A > B, then A has to be true before we can conclude that B is true.
If A is false, who knows anything about B. We haven't gotten there yet.
If B is true, great, but we haven't heard about A. We don't know anything about A.
@NikkiWidra This helped a lot! thank youuuu!
It's the oldest trick in the book, but man, does LSAT know how to play it in a gazillion different ways in varying levels of pure evil
Keep it simple: Think about this:
Only Arabic-speakers get PhDs. Chris is an Arabic speaker. Therefore Chris gets a PhD.
If gets a PhD, then an Arabic Speaker, written
PhD->Arabic-speaker
Now here's where you don't want to mess up. It says Chris is in that "Arabic-Speaker" portion, or in other words, he's someone in the necessary condition position. But we can't work backwards. We can't say if Chris (the necessary) speaks Arabic then he gets a PhD.
It's easier to see if we use three topics, as it builds on earlier lessons:
A->B->C
We can't say "if C, then B"
Pretty please bring back videos.... #Feedback
... did you ever hear the tragedy of Darth Plagueis the Wise?
@clickbaitcowboy It's not a story the Jedi would tell you
Why is he making these lessons harder than they need to be? He clearly states in the previous chapters that we should assign symbols that help us remember as much information as possible and does the complete opposite when giving examples..
This chapter is so confusing, first, using A,B to in Lawgic is not representive enough. Also, the second lawgic is seemingly wrong, but it says it's valid.
Yea I don't know why they chose to use A and B vs. using J and F which would make it much more clear.
By valid I think they mean that it is in an argument format, not that it is necessarily sound.
Both versions would be so helpful!
I do not understand the second example. If the conditional indicator is Only, that translates to logic Uses Force --> Jedi. Since Dooku uses the force, he triggered the sufficient and is a Jedi. This is a valid logic. But why did the text say I made up my own premise? If the conditional indicator is only, I did not make anything up did I? it's very confusing.
I think they are talking about the previous example but it is very confusing nonetheless.
Why is the Lawgic shorthand for Jedi and Force all of the sudden A and B instead of J and F in these examples? It makes it impossible to match english to the Lawgic shorthand in order to follow along. What are we doing here? #feedback
i don't understand why in the Lawgic part of this lesson, is there not an actual usage of the symbols that correlate with the English statement form? It makes understanding this lesson 10x harder than if we could use J for Jedi, F for Force, or CD for Count Dooku.
Facts!
I don't understand the last paragraph "The only problem is that you made up your own premise B -> A. The actual premise is A -> B. You confused sufficiency for necessity."
The rest of the lesson makes sense, but I'm totally lost when I read that. Maybe make a video or remove/clarify that paragraph? I don't see what that really adds here.
@john Agreed that confused me. I think they're just saying that the conditional argument follows A--> B, xA, xB. They chose to flip it for the sake of correcting the example but it does not follow the traditional (correct) conditional argument sequence.
I got home from reviewing demands and medical records to come and read! ughhh where are the videos!!
@LauraBolivar why is this me!!
@jrm98 Because you're responsible lol that's my best guess right now
I am so beyond confused. I feel like we are unlearning everything we just learned.
@AveryRooney28 ME TOOOOOO. I wish their was video of explaining it, instead of just reading it
@marikitten03 I agree. This has been rough the last two lessons.
Idk if this will help some of you all, but it helped me understand this whole thing better.
I found this on 7sage btw.
"So imagine you are given two premises:
1.) A relationship: Y--->G--->H--->B
2.) A fact: Not H
What conclusions can you draw?
Not H is a necessary condition for G AND it is a necessary condition for Y (since Y implies H). So, you are failing a necessary (required) condition for G and Y. Thus, you must have Not G and Not Y.
H is a sufficient condition for B. Failing the sufficient condition doesn't trigger anything because there might be other ways B can trigger".
So if you are failing a necessary condition then you can make a valid conclusion for the sufficient. But if you are satisfying a necessary, then you cannot draw a conclusion about the sufficient, because we dont know what happens to the sufficient.
Valid conclusion: Only dogs play outside. Blanche plays outside. Therefore, Blanche is a dog.
Invalid conclusion: All dogs play outside. Blanche plays outside. Therefore, Blanche is a dog.
In the invalid conclusion, Blanche could be a part of another group since it does not explicitly state that you have to be a dog to play outside. She could be human, a cat, etc.