Another way to think of it: sufficiency guarantees necessity not the other the way around. Being a cat guarantees being a mammal but being a mammal doesn't guarantee being a cat.
@SarahSmile That is a good way of looking at it when there is a subset and superset relationship. However, it becomes a problem in a sufficiency and necessity causal relationship. For example:
A brain death is going to get you killed (body will stop) surely i.e. is sufficient for you to get killed. But that is not necessary for you to get killed. You can get killed in all sorts of ways kidney failure, cancer etc. Death does not require brain death.
This is an example of sufficient but not necessary. That is, sufficiency is not guaranteeing neccessity because maybe there are no necessary ways to get killed.
@Isra I think we’re using “necessary” in slightly different ways. In conditional logic, when we say X is sufficient for Y, we mean that Y is necessary for X. Meaning whenever X occurs, Y must occur. That doesn’t mean Y requires X in all cases. So brain death →death means that the occurrence of brain death guarantees “death” but “death” doesn’t necessarily guarantee that “brain death” occurred. Death could be the result of any other thing.
If one is named Cody, then one will score above 170 on the LSAT. My name is Cody. Therefore, I will score above 170 on the LSAT. J.Y. SAID IT IS VALID!!!!!
Ugh finally. After so many different explanations of sufficiency and necessity in different courses, videos, and books, I think I made a breakthrough!!
Thinking about membership as a subset of a superset really makes it clear. If someone is hungry, then they are angry. Therefore, since I am hungry, I am also unhappy. My friend is unhappy, but that doesn't make them hungry. However, since my other pal is not unhappy, they cannot possibly be hungry.
(this is just an example, don't have that many friends. I am hungry tho)
Does anyone else have days where they can't get any questions right? the drills are humbling me today. Im so scared im going to get to the test and be having one of those days
@purplesunshine007 its so funny because youre the only other person ive ever seen use this form. i worked w a tutor once and i was like oh its like a math equation like they cancel each other out and he was like ... wtf are you talking about ?? I dont have a math brain by any means but these kinds of arguments reminded me of cancelling out two-sided equations lol
@bawstonlaw I’m a philosophy graduate and that’s how we were talked to validate arguments in our logic class. In the back of the book was a list of rules like that one.
@billyg03 The example you shared is just another way of saying what I displayed in my example. The "x" are not negations, they are just a symbol for a variable "x".
For example, xA is not saying "not A". It's just saying "X is an A." So this can also be translated to the same statement I shared above: All As are Bs. X is an A. Therefore, X must also be a B.
Premise 1: membership in a subset is sufficient for membership in a superset. Premise 2: X is a member of the subset. Conclusion: X is a member of the superset. Is that correct
for all of the formal logic people out there, this is is a simple argument form if you break it down into p and q. it would look something like: if p then q (p ->q), p, therefore q. this works because if the first half of a conditional statement is true (which we know it is because of the second premise, then the second half must be true in order for the statement (our original premise of if p -> q) to be true! idk if this helps anyone, but conceptually it works a lot better for me.
Back to my very first philosophy class lol! All men are mortal, Socrates is a man, therefore Socrates is mortal. Thank you philosophy degree for your help in these trying times.
Superset: mortality
Subset: all men
Socrates being a man is sufficient to say that Socrates is mortal, but being mortal isn't enough to say that Socrates is mortal, because animals and plants are mortal as well. (I think this is it)
119 comments
Another way to think of it: sufficiency guarantees necessity not the other the way around. Being a cat guarantees being a mammal but being a mammal doesn't guarantee being a cat.
@SarahSmile That is a good way of looking at it when there is a subset and superset relationship. However, it becomes a problem in a sufficiency and necessity causal relationship. For example:
A brain death is going to get you killed (body will stop) surely i.e. is sufficient for you to get killed. But that is not necessary for you to get killed. You can get killed in all sorts of ways kidney failure, cancer etc. Death does not require brain death.
This is an example of sufficient but not necessary. That is, sufficiency is not guaranteeing neccessity because maybe there are no necessary ways to get killed.
@Isra I think we’re using “necessary” in slightly different ways. In conditional logic, when we say X is sufficient for Y, we mean that Y is necessary for X. Meaning whenever X occurs, Y must occur. That doesn’t mean Y requires X in all cases. So brain death →death means that the occurrence of brain death guarantees “death” but “death” doesn’t necessarily guarantee that “brain death” occurred. Death could be the result of any other thing.
@SarahSmile I understand you now! tnx
premise 1: If you're a Howard alumi, you attended Howard University.
premise 2: Veronica is a Howard alumi.
conclusion: Veronica attended Howard University.
If one is named Cody, then one will score above 170 on the LSAT. My name is Cody. Therefore, I will score above 170 on the LSAT. J.Y. SAID IT IS VALID!!!!!
@codybrowning69 Truth vs. Validity
im cooked
@studyever1234 Real
@studyever1234 YOU GOT THIS!
@studyever1234 take a symbolic logic class if you can, its very helpful for developing logical thinking skills
Ugh finally. After so many different explanations of sufficiency and necessity in different courses, videos, and books, I think I made a breakthrough!!
Thinking about membership as a subset of a superset really makes it clear. If someone is hungry, then they are angry. Therefore, since I am hungry, I am also unhappy. My friend is unhappy, but that doesn't make them hungry. However, since my other pal is not unhappy, they cannot possibly be hungry.
(this is just an example, don't have that many friends. I am hungry tho)
Haha good one!
You have to be a part of the big picture, to be a part of the small picture.
If you are a part of the small picture, you COULD be a part of the big one but not necessarily.
All Elephants are D1 Football players. Roxy is an elephant. Therefore Roxy is a D1 Football player.
Does anyone else have days where they can't get any questions right? the drills are humbling me today. Im so scared im going to get to the test and be having one of those days
@KaraSwider Yep its day 5 for me
Eating Buffalo Chicken Cheese Fries makes you a king. My friend ate Buffalo Chicken Cheese Fries. Therefor, my friend is a king.
@Super_Cookie doing LSAT practice everyday will get you a high score. I'm doing LSAT practice everyday. Therefor, I will get a high score
#powerlevel over 9000 <3
if X then
Yif
Ythen ZTherefore, X then Z
@purplesunshine007 its so funny because youre the only other person ive ever seen use this form. i worked w a tutor once and i was like oh its like a math equation like they cancel each other out and he was like ... wtf are you talking about ?? I dont have a math brain by any means but these kinds of arguments reminded me of cancelling out two-sided equations lol
@bawstonlaw I’m a philosophy graduate and that’s how we were talked to validate arguments in our logic class. In the back of the book was a list of rules like that one.
@purplesunshine007 thats so good to know, we think the same LOL
@purplesunshine007 I like this way of looking at it alot....
Finally had the light bulb moment for this section! Now let's see if I can connect the dots on PTs
So it's just modus ponens?
i find it easier to see the relationship like this:
P: A --> B
P: A
C: B
(All As are Bs. X is an A. Therefore, X must also be a B.)
@billyg03 The example you shared is just another way of saying what I displayed in my example. The "x" are not negations, they are just a symbol for a variable "x".
For example, xA is not saying "not A". It's just saying "X is an A." So this can also be translated to the same statement I shared above: All As are Bs. X is an A. Therefore, X must also be a B.
7sage represents negations with "/"
Hope this helps!
Please don't disrespect Luke!
@MRod It's ok, Star Wars and logical reasoning don't usually go hand in hand.
All of the Sleepless Kingdom has been cursed to sleep. Aurora is from the Sleepless Kingdom. Therefore, she has been cursed to sleep.
Would it be wrong if I replaced "sufficient" with "enough to assume" in my mind when I read the questions?
thats actually how i have been reading it. lol
Premise 1: membership in a subset is sufficient for membership in a superset. Premise 2: X is a member of the subset. Conclusion: X is a member of the superset. Is that correct
@VanillaCat yes!
Will the premises always be assumed true? like not all turtles are ninjas, but for the test we assume this is the case?
@SusanLeifker Oh lol it's the very next video
for all of the formal logic people out there, this is is a simple argument form if you break it down into p and q. it would look something like: if p then q (p ->q), p, therefore q. this works because if the first half of a conditional statement is true (which we know it is because of the second premise, then the second half must be true in order for the statement (our original premise of if p -> q) to be true! idk if this helps anyone, but conceptually it works a lot better for me.
Back to my very first philosophy class lol! All men are mortal, Socrates is a man, therefore Socrates is mortal. Thank you philosophy degree for your help in these trying times.
Superset: mortality
Subset: all men
Socrates being a man is sufficient to say that Socrates is mortal, but being mortal isn't enough to say that Socrates is mortal, because animals and plants are mortal as well. (I think this is it)
premise 1: All astronauts are donkeys.
premise 2: Mickey Mouse is an astronaut.
conclusion: Mickey Mouse is a donkey.
VALID!
If you are 17 years or older, you can go to a rated R movie alone. Adrian went to see Sinners alone, so Adrian is 17 years or older.
Eating spinach guarantees eating a vegetable. But eating a vegetable doesn't guarantee eating spinach.
All dromeosaurs are dinosaurs. Velociraptor is a dromeosaur, therefore Velociraptor is a dinosaur
A is B. C is A. therefore C is B
Right?